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1
RADAMPOLA, Senanie Sujeewa, and senanie s. radampola@mainroads qld gov au. "EVALUATION AND MODELLING PERFORMANCE OF CAPPING LAYER IN RAIL TRACK SUBSTRUCTURE." Central Queensland University. Centre for Railway Engineering, 2006. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20060817.115415.
Full textAbstract:
In the design of rail track structures where the subgrade cannot achieve the desired
capacity, enabling the required standard of track geometry to be maintained for the speed,
axle load and tonnage to be hauled, a capping layer of granular material is placed
between the natural ground or the embankment fill material and the ballast to protect the
underlying weaker layers.
In spite of the important role played by the capping layer, very little research has been
carried out on its performance. The current practice of design of the capping layer,
therefore, is based on working stress philosophy where reduced levels of stresses are
assumed not to degrade the subgrade. Even on tracks containing a thick ballast layer that
ensures allowable levels of working stress the subgrade has been found to have
permanently deformed. Design of capping layers based on plastic deformation,
therefore, appears appropriate. This thesis aims at determining the load levels that cause
detrimental plastic deformation in the capping layer.
The suite of material properties that characterise plastic deformations of capping layer is
neither readily available nor easily determined. This thesis proposes a cheaper method of
evaluating a range of capping layer material properties using penetration tests on
specimens contained in California Bearing Ratio (CBR) test moulds coupled with a finite
element modelling based back calculation technique. The suite of material properties
thus determined are used for the simulation of the behaviour of capping layers under the
boundary and loading conditions similar to those in practice. The predicted results are
validated using laboratory experiments on large size capping layer specimens.
2
Pilli, Aparna. "Atomic Layer Deposition of Boron Oxide and Boron Nitride for Ultrashallow Doping and Capping Applications." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1752373/.
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The deposition of boron oxide (B₂O₃) films on silicon substrates is of significant interest in microelectronics for ultrashallow doping applications. However, thickness control and conformality of such films has been an issue in high aspect ratio 3D structures which have long replaced traditional planar transistor architectures. B₂O₃ films are also unstable in atmosphere, requiring a suitable capping barrier for passivation. The growth of continuous, stoichiometric B₂O₃ and boron nitride (BN) films has been demonstrated in this dissertation using Atomic Layer Deposition (ALD) and enhanced ALD methods for doping and capping applications.
Low temperature ALD of B₂O₃ was achieved using BCl₃/H₂O precursors at 300 K. In situ x-ray photoelectron spectroscopy (XPS) was used to assess the purity and stoichiometry of deposited films with a high reported growth rate of ~2.5 Å/cycle. Free-radical assisted ALD of B₂O₃ was also demonstrated using non-corrosive trimethyl borate (TMB) precursor, in conjunction with mixed O₂/O-radical effluent, at 300 K. The influence of O₂/O flux on TMB-saturated Si surface was investigated using in situ XPS, residual gas analysis mass spectrometer (RGA-MS) and ab initio molecular dynamics simulations (AIMD). Both low and high flux regimes were studied in order to understand the trade-off between ligand removal and B₂O₃ growth rate. Optimization of precursor flux was discovered to be imperative in plasma and radical-assisted ALD processes.
BN was investigated as a novel capping barrier for B₂O₃ and B-Si-oxide films. A BN capping layer, deposited using BCl₃/NH₃ ALD at 600 K, demonstrated excellent stoichiometry and consistent growth rate (1.4 Å/cycle) on both films. Approximately 13 Å of BN was sufficient to protect ~13 Å of B₂O₃ and ~5 Å of B-Si-oxide from atmospheric moisture and prevent volatile boric acid formation. BN/B₂O₃/Si heterostructures are also stable at high temperatures (>1000 K) commonly used for dopant drive-in and activation. BN shows great promise in preventing upward boron diffusion which causes a loss in the dopant dose concentration in Si.
The capping effects of BN were extended to electrochemical battery applications. ALD of BN was achieved on solid Li-garnet electrolytes using halide-free tris(dimethylamino)borane precursor, in conjunction with NH₃ at 723 K. Approximately 3 nm of BN cap successfully inhibited Li₂CO₃ formation, which is detrimental to Li-based electrolytes. BN capped Li-garnets demonstrated ambient stability for at least 2 months of storage in air as determined by XPS. BN also played a crucial role in stabilizing Li anode/electrolyte interface, which drastically reduced interfacial resistance to 18 Ω.cm², improved critical current density and demonstrated excellent capacitance retention of 98% over 100 cycles. This work established that ALD is key to achieving conformal growth of BN as a requirement for Li dendrite suppression, which in turn influences battery life and performance.
3
Samuelsson, Göran S. "In situ remediation of contaminated sediments using thin-layer capping : efficiency in contaminant retention and ecological implications." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-94845.
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Hydrophobic organic contaminants (HOCs) often reside in sediments sorbed to particles, most tightly to particles with high content of organic carbon. If persistent, such pollutants can accumulate in the sediment for many years and constitute a contamination risk for sediment-living organisms and organisms at higher trophic levels, including humans. Since traditional remediation techniques are associated with complications (e.g. release of contaminants during dredging operations, disturbance of benthic faunal communities), or constraints (handling of large amounts of contaminated sediment and water, limitations due to depth and size of the area, high costs), there is a need for new alternative methods. In situ remediation through thin-layer capping (a few centimeter cover) with a sorbing material such as activated carbon (AC) has been proposed as an alternative remediation method. Compared to traditional remediation techniques, AC amendment in a thin layer means less material handling and lower costs and is assumed to be less disruptive to benthic communities. The objectives of this thesis were to investigate the ecological effects from thin layer capping as well as the efficiency in contaminant retention. Thin layer capping amended with AC proved to reduce availability of HOCs to the tested organisms, the gastropod Nassarius nitidus (Paper II), the clam Abra nitida (Paper III) and to polychaete worms (Paper II and III). The remediation technique also decreased the sediment-to-water fluxes of the contaminants (Paper II and III). However, AC amended thin-layer capping was also found to cause negative biological effects. In laboratory studies with only a few species the negative effects were minor, or difficult to discern with the endpoints used (Paper II and III). In a larger multi-species mesocosm (boxcore) study, on the other hand, the negative effects were more prominent (Paper I) and in a large scale field study the benthic community was found to be profoundly disturbed by the AC amendment, with the effects persisting or even worsening ca one year (14 months) post amendment (Paper IV).At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 3: Manuscript; Paper 4: Manuscript.
Carbocap
Opticap
Thinc
4
Pantzare, Nathalie. "Biochar-based thin-layer capping of contaminated sediment in Burefjärden, northern Sweden : Assessment of biochar mixed into four structural materials for preventing release of trace elements from sediment to water." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-87235.
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Coastal areas around the world have been recognized as largely impacted by anthropogenic activities resulting in pollution of marine sediments. In Sweden, surveys conducted along the coastline of the Bothnian Bay have identified a total area of about 29 km2 as fiber rich sediments. In the Bureå sea area near Skellefteå vicinity, Västerbotten county, elevated levels of mercury (Hg), methyl-Hg, arsenic (As), copper (Cu), lead (Pb), cadmium (Cd), zinc (Zn) and polycyclic aromatic hydrocarbons (PAH) have been classified and believed to be mainly affected by emissions from a pulp and paper industry formerly active on a nearby headland. Contaminants in sediments are of concern as continuous dispersion can adversely affect the benthic community. To isolate contaminants and reduce their bioavailability, in-situ thin-layer capping using an active material is one suitable approach. This type of remediation method, using biochar mixed with bentonite clay will be implemented on a pilot scale in the sea area outside of Bureå in the spring of 2021. However, bentonite is a relatively expensive material yielding a need to further develop the selection of capping materials suitable to aid in the deposition of biochar in an active thin-layer cap. In this thesis, biochar-based thin layer caps mixed with bentonite clay, rock dust of two grain sizes and a concrete-based slurry was evaluated on their physicochemical properties and efficiency for preventing release of trace elements from sediment to the overlying water. This was conducted by a laboratory column experiment where four set ups were performed: (1) no capping for sediment control, (2) only capping material for material control, (3) sediment mixed with biochar and (4) sediment capped with each material mixed with biochar. Three times during an 8-week test period, 60 mL of the overlying water in the columns was extracted and sent for trace element analysis. The experimental set up revealed that the capping layers effectively prevent release of trace elements trough the sediment to the overlying water. The concrete slurry showed suitable settling properties and negligible loss of biochar in the set-up of the columns. Also, the biochar+concrete slurry thin-layer cap displayed the highest efficiency for preventing and/or delaying release of As, P, Cu, Fe, Mn and SO4.
5
Almasi, H., C. L. Sun, X. Li, T. Newhouse-Illige, C. Bi, K. C. Price, S. Nahar, et al. "Perpendicular magnetic tunnel junction with W seed and capping layers." AMER INST PHYSICS, 2017. http://hdl.handle.net/10150/624048.
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We present a study on perpendicular magnetic tunnel junctions with W as buffer and capping layers. A tunneling magnetoresistance of 138% and an interfacial magnetic anisotropy of 1.67 erg/cm(2) were obtained in optimally annealed samples. However, after extended annealing at 420 degrees C, junctions with W layers showed extremely small resistance due to interdiffusion of W into the MgO barrier. In contrast, in Ta-based junctions, the MgO barrier remained structurally stable despite disappearance of magnetoresistance after extended annealing due to loss of perpendicular magnetic anisotropy. Compared with conventional tunnel junctions with in-plane magnetic anisotropy, the evolution of tunneling conductance suggests that the relatively low magnetoresistance in perpendicular tunnel junctions is related to the lack of highly polarized Delta(1) conducting channel developed in the initial stage of annealing. Published by AIP Publishing.
6
Josefsson, Sarah. "Fate and transport of POPs in the aquatic environment : with focus on contaminated sediments." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-42107.
Full textAbstract:
Persistent organic pollutants (POPs) are hydrophobic substances that readily sorb to organic matter in particles and colloids instead of being freely dissolved in the water phase. This sorption affects the bioavailability and environmental transport of the POPs. The major part of this thesis concerns the role of sediments as secondary sources of POPs. As the primary emissions decrease, contaminated sediments where POPs have accumulated can become the main source of contamination. If the contaminated sediment by time becomes covered with cleaner layers, the POPs are buried and no longer in contact with the aquatic environment. Experiments in this thesis showed, however, that new invading species can alter the sediment-water dynamics as a result of their bioturbation, i.e. mixing of sediment particles and pore-water. Marenzelleria spp., invading species in the Baltic Sea that burrow deeper than native species, were found to increase the remobilization of buried contaminants. The sediment-to-water flux was inversely related to the burial depth (2-10 cm) of the POP congeners (polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers) and also inversely related to the hydrophobicity of the congener. The flux was therefore most pronounced for less hydrophobic contaminants, which was linked to the bioirrigating behaviour of these species. Marenzelleria spp. also accumulated the buried POPs and increased concentrations in surface sediment. Contaminants previously considered buried at a ’safe’ depth can thus be remobilized as a result of the invasion of Marenzelleria spp. in the Baltic Sea. One method to decrease the remobilization of contaminants from sediments is ’capping’, i.e. a layer of clean material is placed as a cap on the sediment. By amending the cap with active materials, which sequester the POPs and decrease their availability, thinner layers can be used (’active capping’ or ’thin-layer capping’). Results from an experiment with thin-layer capping using different active materials (activated carbon (AC) and kraft lignin) showed that both the sediment-to-water flux and the bioaccumulation by benthic species of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), hexachlorobenzene (HCB) and octachlorostyrene (OCS) decreased with increased thickness of the cap layer (0.5-5 cm). Amendments with active materials further increased the cap efficiency. AC was more efficient than kraft lignin, and a 3 cm cap with 3.3% AC reduced the flux and bioaccumulation with ~90%. The reduction of the sediment-to-water flux was inversely related to the hydrophobicity of the POP, and reductions in the flux had similar magnitudes as reductions in the concentration in deep-burrowing polychaetes, demonstrating the importance of bioturbation for sediment-to-water transport. In a one-year study on the levels of PCDD/Fs, PCBs, and HCB in a coastal area of the Baltic Sea, the correlations between the POP levels and the levels of particles and organic carbon in the water were found to differ for POPs of different structure and hydrophobicity. The levels of PCDD/Fs decreased to one third in May, which could be related to the increased sedimentation, i.e. water-to-sediment transport, during spring bloom.
7
Pretel, Hermes. "Reparação tecidual pulpar sob ação bioestimuladora do laser de baixa intensidade (LILT), e do diodo emissor de luz (LED): estudo em macacos prego /." Araraquara : [s.n.], 2008. http://hdl.handle.net/11449/104266.
Full textAbstract:
Orientador: Lizeti Toledo de Oliveira RamalhoBanca: Lourdes Aparecida Martins dos Santos Pinto
Banca: Ana Maria Minarelli Gaspar
Banca: Maria Cristina Borsatto
Banca: Nivaldo Parizotto
Resumo: O estudo investigou os efeitos da radiação eletromagnética não ionizante emitidos pelos diodos LASER com comprimento de onda no espectro 688 ηm e 785 ηm, e diodo LED 635 ± 10 ηm, associados ao capeamento direto com hidróxido de cálcio em exposições pulpares mecânicas. Avaliou-se assim em dentes de macacos-prego a resposta pulpar baseado na morfologia das células pulpares, no processo inflamatório local, na formação da barreira mineralizada, e na organização do tecido pulpar nos diferentes grupos estudados. Discutiu-se também as diferentes fontes de emissão de radiação eletromagnética comparando os resultados obtidos de estimulação pulpar com os diodos LASER e LED, os quais apresentam energia coerente e não-coerente, respectivamente. Os resultado mostraram uma estimulação em todos os grupos irradiados com melhores resultados para o estímulo com LASER, quando comparado ao grupo tratado isoladamente com hidróxido de cálcio. Concluímos assim que a estimulação de energia eletromagnética LASER e LED associado ao capeamento pulpar direto com hidróxido de cálcio apresentou aceleração no processo de reparação tecidual. Porém, há necessidade de novos estudos com diferentes parâmetros de irradiação a fim de se obter protocolos cada vez mais eficientes para o estudo dos efeitos da luz sobre o processo de reparação pulpar.
Abstract: The aim of this study was to compare the effects of non-ionizing electromagnetic radiation emitted by LASER diodes 688 ηm and 785 ηm, and LED diode 635 ± 10 ηm associated to direct pulp capping with calcium hydroxide in traumatic pulp exposures were investigated. Based on pulp cells morphology, on the local inflammatory process, on mineralized barrier formation and on pulp tissue organization, the pulp response in capuchin monkey teeth was evaluated in different groups. It was also discussed the different electromagnetic radiation emission sources effects comparing the obtained results of pulp stimulation with diodes LASER and LED, which present coherent and non-coherent energy respectively. Stimulation was observed in all irradiated groups, being the best results achieved with LASER stimulation, when compared to the group treated only with calcium hydroxide. Thus, it is concluded that the electromagnetic LASER and LED energy stimulation associated with calcium hydroxide direct pulp capping accelerated the tissue repair process. However, further studies with different stimulation parameters in order to obtain increasingly efficient protocols to study light effects on pulp repair are necessary.
Doutor
8
White, Benjamin C. "Investigating the effect of capping layers on final thin film morphology after a dewetting process." Thesis, Utah State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10137688.
Full textAbstract:
Nanoparticles on a substrate have numerous applications in nanotechnology, from enhancements to solar cell efficiency to improvements in carbon nanotube growth. Producing nanoparticles in a cheap fashion with some control over size and spacing is difficult to do, but desired. This work presents a novel method for altering the radius and pitch distributions of nickel and gold nanoparticles in a scalable fashion. The introduction of alumina capping layers to thin nickel films during a pulsed laser-induced dewetting process has yielded reductions in the mean and standard deviation of radii and pitch for dewet nanoparticles. Carbon nanotube mats grown on these samples show a much thicker mat for the capped case. The same capping layers have produced an opposite effect of increased nanoparticle size and spacing during a solid state dewetting process of a gold film. These results also show a decrease in the magnitude of the effect as the capping layer thickness increases. Since the subject of research interest for using these nanoparticles has shifted towards producing ordered arrays with size and spacing control, the uncertainty in the values of these distributions needs to be quantified for any form of meaningful comparison to be made between fabrication methods. Presented here is a first step in the uncertainty analysis of such samples via synthetic images producing error distributions.
9
Holt, Christopher Charles. "The effect of mellowing periods on lime treated British clays used in highway pavement capping layers." Thesis, University of Birmingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422398.
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Crisci, Fernando Simões. "Efeito do laser de baixa intensidade na polpa e nos tecidos apicais e periapicais em dentes de macaco /." Araraquara : [s.n.], 2008. http://hdl.handle.net/11449/101654.
Full textAbstract:
Orientador: Lizeti Toledo de Oliveira RamalhoBanca: Fábio Luiz Camargo Villela Berbert
Banca: Welingtom Dinelli
Banca: Manoel Damião de Souza Neto
Banca: Antônio Miranda da Cruz Filho
Resumo: O presente estudo avaliou o efeito do laser de baixa intensidade diodo semicondutor de arseneto de gálio e alumínio em exposições pulpares induzidas e nos tecidos apicais e periapicais após tratamento endodôntico em dentes de macacos. Nas exposições pulpares, foi avaliado efeito do laser infra-vermelho associado ao hidróxido de cálcio, variando o tempo de aplicação, onde utilizou-se quatro macacos, totalizando 24 dentes, distribuídos em quatro grupos experimentais: Grupo I: Laser 2,5 segundos (dentes incisivos), Grupo II: Laser 40 segundos (dentes incisivos), Grupo III: Laser 40 segundos (dentes prémolares) e Grupo IV: Controle sem Laser (dentes pré-molares), por um período de 55 dias. Quanto ao efeito do laser sobre a agressividade tecidual do cimento endodôntico óxido de zinco e eugenol (OZE), após tratamento endodôntico nos tecidos apicais e periapicais, foi comparando o laser vermelho com o infravermelho, utilizando quatro macacos, totalizando 24 dentes, distribuídos em três grupos experimentais: Grupo I (Laser Vermelho), Grupo II (laser Infra-Vermelho) e Grupo III (Controle: Sem Laser), por um período de 22 dias. Decorrido os períodos experimentais de cada estudo, os animais foram mortos, os dentes ou peças removidas e preparadas para análise histológica. De acordo com a proposta e as condições específicas deste trabalho, os resultados nos permitem concluir que nas exposições pulpares, a irradiação com laser infra-vermelho (40 segundos) diminuiu a reação inflamatória e induziu a organização tecidual, bem como na formação da barreira mineralizada, apresentando diferenças estatísticas significantes entre os grupos (p<0,05), tendo como melhor resultado a irradiação com laser infra-vermelho (40 segundos), já nos tecidos apicais e periapicais a irradiação... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The present study evaluated the effect of the laser of low intensity diode semiconductor of gallium aluminum arsenide in exposed pulp induced in apical and periapical tissues after endodontic treatment in teeth of monkeys. In the exposed pulp, the effect of the laser infra-red associated to the hydroxide of calcium was evaluated varying the time of application, being used 04 monkeys, totaling 24 teeth, distributed in four experimental groups: Group I: Laser 2,5 seconds (incisive teeth), Group II: Laser 40 seconds (incisive teeth), Group III: Laser 40 seconds (premolar teeth) and Group IV: Control without Laser (premolar teeth), for a period of 55 days. As for the effect of the laser on the tissue aggressiveness of the endodontic zinco oxide and eugenol (OZE) sealer, after endodontic treatment o in the apical and Periapical tissues, the red laser was compared with the laser infra-red, using 04 monkeys, totaling 24 teeth, distributed in 03 experimental groups: Group I (Red Laser), Group II (Infra-red laser) and Group III (it Controls: Without Laser), for a period of 22 days. After the experimental periods of each study, the animals were killed, the teeth or pieces were removed and prepared for histological analysis. In agreement with the proposal and the specific conditions of this study work, the results allow to conclude us that in exposed pulp infra-red laser irradiation (40 seconds.) reduced the inflammatory reaction and induced the tissue organization, as well as the mineralized barrier formation and in apical and periapical tissues infra-red laser irradiation stimulated the cells of the periodontal tissue inducing periapical repair.
Doutor
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Pretel, Hermes [UNESP]. "Reparação tecidual pulpar sob ação bioestimuladora do laser de baixa intensidade (LILT), e do diodo emissor de luz (LED): estudo em macacos prego." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/104266.
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pretel_h_dr_arafo.pdf: 3205750 bytes, checksum: ce5e74583f1240f03a35e00b3edb32bb (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O estudo investigou os efeitos da radiação eletromagnética não ionizante emitidos pelos diodos LASER com comprimento de onda no espectro 688 ηm e 785 ηm, e diodo LED 635 ± 10 ηm, associados ao capeamento direto com hidróxido de cálcio em exposições pulpares mecânicas. Avaliou-se assim em dentes de macacos-prego a resposta pulpar baseado na morfologia das células pulpares, no processo inflamatório local, na formação da barreira mineralizada, e na organização do tecido pulpar nos diferentes grupos estudados. Discutiu-se também as diferentes fontes de emissão de radiação eletromagnética comparando os resultados obtidos de estimulação pulpar com os diodos LASER e LED, os quais apresentam energia coerente e não-coerente, respectivamente. Os resultado mostraram uma estimulação em todos os grupos irradiados com melhores resultados para o estímulo com LASER, quando comparado ao grupo tratado isoladamente com hidróxido de cálcio. Concluímos assim que a estimulação de energia eletromagnética LASER e LED associado ao capeamento pulpar direto com hidróxido de cálcio apresentou aceleração no processo de reparação tecidual. Porém, há necessidade de novos estudos com diferentes parâmetros de irradiação a fim de se obter protocolos cada vez mais eficientes para o estudo dos efeitos da luz sobre o processo de reparação pulpar.
The aim of this study was to compare the effects of non-ionizing electromagnetic radiation emitted by LASER diodes 688 ηm and 785 ηm, and LED diode 635 ± 10 ηm associated to direct pulp capping with calcium hydroxide in traumatic pulp exposures were investigated. Based on pulp cells morphology, on the local inflammatory process, on mineralized barrier formation and on pulp tissue organization, the pulp response in capuchin monkey teeth was evaluated in different groups. It was also discussed the different electromagnetic radiation emission sources effects comparing the obtained results of pulp stimulation with diodes LASER and LED, which present coherent and non-coherent energy respectively. Stimulation was observed in all irradiated groups, being the best results achieved with LASER stimulation, when compared to the group treated only with calcium hydroxide. Thus, it is concluded that the electromagnetic LASER and LED energy stimulation associated with calcium hydroxide direct pulp capping accelerated the tissue repair process. However, further studies with different stimulation parameters in order to obtain increasingly efficient protocols to study light effects on pulp repair are necessary.
12
Crisci, Fernando Simões [UNESP]. "Reação histológica de exposições pulpares em dentes de ratos à aplicação do laser de baixa intensidade somente ou em associação ao capeamento com hidróxido de cálcio." Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/90426.
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crisci_fs_me_arafo.pdf: 2027540 bytes, checksum: 4b3628dd1cdd46049844ef97ba6d858a (MD5)O presente estudo avaliou a reação histológica do efeito do laser de baixa intensidade diodo semicondutor de arseneto de gálio e alumínio (GaA1As, com comprimento de onda de 785 nm, infravermelho, com potência de emissão de 50 mW, densidade de energia de 3 J/cm2, em emissão contínua, por meio de ponta especial de fibra óptica, por um período de 2 segundos) em exposições pulpares induzidas em dentes de ratos. Foram utilizados 60 ratos, dos quais cada animal ofereceu dois dentes (totalizando 120), que foram distribuídos em 5 grupos experimentais: grupo I (controle), exposição capeada com hidróxido de cálcio; grupo II, laser imediato + hidróxido de cálcio; grupo III, laser imediato + hidróxido de cálcio + laser após 24 horas; grupo IV, laser imediato + hidróxido de cálcio + laser após 24 e 48 horas; e grupo V, somente a aplicação do laser. Decorridos os períodos experimentais de sete e 30 dias, os animais foram mortos, as peças removidas e preparadas para análise histológica. De acordo com a proposta e as condições específicas deste trabalho, os resultados nos permitem concluir que as associações laser imediato + hidróxido de cálcio e laser imediato + hidróxido de cálcio + laser 24 horas, foram os grupos que apresentaram os melhores resultados tanto aos sete dias (efeito antiinflamatório), quanto aos trinta dias (efeito no reparo tecidual).
The present study evaluated the histological reaction of the low poweer laser effect, diode laser semiconductor of gallium aluminum arsenide (GaA1As, with wavelenght of 785 nm, infra-red, potency of emission of 50 mW, energy density of 3 J/cm2, with continuous emission, through special tip of optic fiber, for a period of two seconds) in exposed pulp induced in teeth of mice. Sixty mice were used, of which each animal offered two teeth (totaling 120), that were distributed in 5 experimental groups: group I(control group) exposed capping with calcium hydroxide; group II, immediate laser + calcium hydroxide; group III, immediate laser + calcium hydroxide + laser after 24 hours; group IV, immediate laser + calcium hydroxide + laser after 24 and 48 hours; and group V, only laser application. After the experimental periods of seven and thirty days, the animals were killed, the pieces were removed and prepared for histological analysis. In agreement with the proposal and the specific conditions of this study, the results allow us conclude that the associations of immediate laser + calcium hydroxide and immediate laser + calcium hydroxide + laser after 24 hours, were the groups that presented the best results in the periods of seven days (anti-inflammatory effect), and thirty days (effect in the tissue repair).
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Crisci, Fernando Simões [UNESP]. "Efeito do laser de baixa intensidade na polpa e nos tecidos apicais e periapicais em dentes de macaco." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/101654.
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crisci_fs_dr_arafo.pdf: 2406575 bytes, checksum: 7ed8c4c8f95948faa1e0430e502e380a (MD5)Universidade Estadual Paulista (UNESP)
O presente estudo avaliou o efeito do laser de baixa intensidade diodo semicondutor de arseneto de gálio e alumínio em exposições pulpares induzidas e nos tecidos apicais e periapicais após tratamento endodôntico em dentes de macacos. Nas exposições pulpares, foi avaliado efeito do laser infra-vermelho associado ao hidróxido de cálcio, variando o tempo de aplicação, onde utilizou-se quatro macacos, totalizando 24 dentes, distribuídos em quatro grupos experimentais: Grupo I: Laser 2,5 segundos (dentes incisivos), Grupo II: Laser 40 segundos (dentes incisivos), Grupo III: Laser 40 segundos (dentes prémolares) e Grupo IV: Controle sem Laser (dentes pré-molares), por um período de 55 dias. Quanto ao efeito do laser sobre a agressividade tecidual do cimento endodôntico óxido de zinco e eugenol (OZE), após tratamento endodôntico nos tecidos apicais e periapicais, foi comparando o laser vermelho com o infravermelho, utilizando quatro macacos, totalizando 24 dentes, distribuídos em três grupos experimentais: Grupo I (Laser Vermelho), Grupo II (laser Infra-Vermelho) e Grupo III (Controle: Sem Laser), por um período de 22 dias. Decorrido os períodos experimentais de cada estudo, os animais foram mortos, os dentes ou peças removidas e preparadas para análise histológica. De acordo com a proposta e as condições específicas deste trabalho, os resultados nos permitem concluir que nas exposições pulpares, a irradiação com laser infra-vermelho (40 segundos) diminuiu a reação inflamatória e induziu a organização tecidual, bem como na formação da barreira mineralizada, apresentando diferenças estatísticas significantes entre os grupos (p<0,05), tendo como melhor resultado a irradiação com laser infra-vermelho (40 segundos), já nos tecidos apicais e periapicais a irradiação...
The present study evaluated the effect of the laser of low intensity diode semiconductor of gallium aluminum arsenide in exposed pulp induced in apical and periapical tissues after endodontic treatment in teeth of monkeys. In the exposed pulp, the effect of the laser infra-red associated to the hydroxide of calcium was evaluated varying the time of application, being used 04 monkeys, totaling 24 teeth, distributed in four experimental groups: Group I: Laser 2,5 seconds (incisive teeth), Group II: Laser 40 seconds (incisive teeth), Group III: Laser 40 seconds (premolar teeth) and Group IV: Control without Laser (premolar teeth), for a period of 55 days. As for the effect of the laser on the tissue aggressiveness of the endodontic zinco oxide and eugenol (OZE) sealer, after endodontic treatment o in the apical and Periapical tissues, the red laser was compared with the laser infra-red, using 04 monkeys, totaling 24 teeth, distributed in 03 experimental groups: Group I (Red Laser), Group II (Infra-red laser) and Group III (it Controls: Without Laser), for a period of 22 days. After the experimental periods of each study, the animals were killed, the teeth or pieces were removed and prepared for histological analysis. In agreement with the proposal and the specific conditions of this study work, the results allow to conclude us that in exposed pulp infra-red laser irradiation (40 seconds.) reduced the inflammatory reaction and induced the tissue organization, as well as the mineralized barrier formation and in apical and periapical tissues infra-red laser irradiation stimulated the cells of the periodontal tissue inducing periapical repair.
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Crisci, Fernando Simões. "Reação histológica de exposições pulpares em dentes de ratos à aplicação do laser de baixa intensidade somente ou em associação ao capeamento com hidróxido de cálcio /." Araraquara : [s.n.], 2002. http://hdl.handle.net/11449/90426.
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Resumo: O presente estudo avaliou a reação histológica do efeito do laser de baixa intensidade diodo semicondutor de arseneto de gálio e alumínio (GaA1As, com comprimento de onda de 785 nm, infravermelho, com potência de emissão de 50 mW, densidade de energia de 3 J/cm2, em emissão contínua, por meio de ponta especial de fibra óptica, por um período de 2 segundos) em exposições pulpares induzidas em dentes de ratos. Foram utilizados 60 ratos, dos quais cada animal ofereceu dois dentes (totalizando 120), que foram distribuídos em 5 grupos experimentais: grupo I (controle), exposição capeada com hidróxido de cálcio; grupo II, laser imediato + hidróxido de cálcio; grupo III, laser imediato + hidróxido de cálcio + laser após 24 horas; grupo IV, laser imediato + hidróxido de cálcio + laser após 24 e 48 horas; e grupo V, somente a aplicação do laser. Decorridos os períodos experimentais de sete e 30 dias, os animais foram mortos, as peças removidas e preparadas para análise histológica. De acordo com a proposta e as condições específicas deste trabalho, os resultados nos permitem concluir que as associações laser imediato + hidróxido de cálcio e laser imediato + hidróxido de cálcio + laser 24 horas, foram os grupos que apresentaram os melhores resultados tanto aos sete dias (efeito antiinflamatório), quanto aos trinta dias (efeito no reparo tecidual).Abstract: The present study evaluated the histological reaction of the low poweer laser effect, diode laser semiconductor of gallium aluminum arsenide (GaA1As, with wavelenght of 785 nm, infra-red, potency of emission of 50 mW, energy density of 3 J/cm2, with continuous emission, through special tip of optic fiber, for a period of two seconds) in exposed pulp induced in teeth of mice. Sixty mice were used, of which each animal offered two teeth (totaling 120), that were distributed in 5 experimental groups: group I(control group) exposed capping with calcium hydroxide; group II, immediate laser + calcium hydroxide; group III, immediate laser + calcium hydroxide + laser after 24 hours; group IV, immediate laser + calcium hydroxide + laser after 24 and 48 hours; and group V, only laser application. After the experimental periods of seven and thirty days, the animals were killed, the pieces were removed and prepared for histological analysis. In agreement with the proposal and the specific conditions of this study, the results allow us conclude that the associations of immediate laser + calcium hydroxide and immediate laser + calcium hydroxide + laser after 24 hours, were the groups that presented the best results in the periods of seven days (anti-inflammatory effect), and thirty days (effect in the tissue repair).
Orientador: Fábio Luiz Camargo Villela Berbert
Coorientador: Lizeti Toledo de Oliveira Ramalho
Banca: Renato de Toledo Leonardo
Banca: Jesus Djalma Pécora
Mestre
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Chiu, Chi-Kuang, and 邱繼廣. "AlN capping layer for ion implantation." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/98591244598944506827.
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碩士國立中央大學
物理研究所
91
In this thesis, we deposited an AlN capping layer on GaN to prevent the decomposition of GaN surface. GaN films were grown by MOCVD at about 1050℃. In the thermal annealing process after ion implantation, the temperature higher than 1050℃ will cause the decomposition of GaN surface. By using the Hall measurement, we compared the electrical properties of GaN with AlN capping layer and without capping after thermal annealing. The 28Si+ implantation into p-type GaN followed by thermal annealing will makes the electrical properties transform from p-type to n-type. In the Hall measurement results, the GaN without capping has carrier concentration about 3.73x1013 cm-2, and the GaN with capping layer has carrier concentration about 1.02x1014 cm-2. Activation efficiency was improved from 3.7% to 10%. If the GaN substrates were heated during deposition process, then the adhesion of AlN films on GaN will be better to get improvement for protection on GaN surface.
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Kuo, Je Ming, and 郭哲銘. "Investigating the Capping-layer effect on the PbAu alloy layer." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/69367197347650542123.
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碩士國立清華大學
先進光源科技學位學程
103
The previous research shows that that a binary alloy composed of heavy atoms, Pb and Au, has large Rashba effect, yielding two cones at Γ ̅ and two giant Rashba splitting at M ̅. Experiments and first-principles calculations of the electronic structure indicated that such a Rashba effect may be produced only via a special buckling configuration induced by squeezing from the top Au capping layers and bottom Pb films. In this research, we demonstrated that with Bi as the capping layer on PbAu alloy, the Rashba effect is reproduced as well. This result means that Rashba-splitting band structure of PbAu alloy layer is caused by a capping layer on the top, which breaks the inversion symmetry and enhances the buckling height. We tried to deposit Bi onto PbAu alloy layer at Room temperature and low temperature, T = -130 ˚C, respectively and found that Rashba-splitting band structure only showed up at room temperature. It means that the atoms of capping layer must be at specific locations that are commensurate with Au atoms of alloy. In addition, we found that the binding energy of Rashba-splitting band structure shifted into higher binding energy and dispersion changed, indicating that we can use different kinds of atoms as the capping layer to tune the Rashba effect of the middle alloy.
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Lin, Bin-Chan, and 林炳全. "Effect of capping superconductive layer and MgO spacer ontunnel magnetoresistance." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/80787272796198411497.
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碩士國立臺灣大學
物理研究所
95
Magnetic tunnel junction is a promising candidate for applications in magnetic-storage technology, such as non-volatile memory, read head and magnetic sensors. Much higher tunnel magnetoresistance and lower resistance of junctions provide the feasibility for high-density magnetoresistive random-access-memory (MRAM) and less power consumption. We investgated the influence upon structure of magnetic tunnel junctions, including added capping layer and modification of spacer. We found that the TMR ratio drastically decreased with capping superconductive Nb. The thickness of capping Nb layer was varied onto TMR junctions to investgate the relation between superconductor and magnetism. Another TMR structure was examined on altering spacer. Huge TMR values have been theoretically predicted in (100) oriented single-crystalline Fe/MgO/Fe MTJs. We have fabricated MgO barrier layer which was sandwiched with amorphous CoFeB electrodes by magnetron supttering. We exhibit a well-defined parallel/antiparallel magnetic configuration by invoking Magneto-Optical Kerr Effect(MOKE), and adjust the thickness of MgO barrier to optimize TMR ratio. The annealing effect was also investigated to promote TMR value.
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Chien, Chih-Yu, and 簡志育. "Investigation on the biomimetic crystallization layer as pulp capping biomaterial." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/58836871717405048178.
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碩士國立臺灣大學
口腔生物科學研究所
104
Pulp capping is applied to a deep tooth cavity for keeping the pulp vitality. The following light cured composite resin is always applied to recovery the original morphology and chewing function. However, it containing toxic monomers may permeate through dentinal tubules to cause pulp damage. The purpose of this research project is to develop nano-calcium encapsulated mesocellular siliceous foams (denoted as nCa-MCFs) as a capping biomaterial that can form biomimetic crystallization in dentinal tubule when nCa-MCFs works with phosphoric acid (denoted as nCa-MCFs-HP). The biomimetic crystal layer would serve as a protective barrier protect pulp tissues from the toxic monomer of dentin bonding agents, and further induces the differentiation of odontoblast. This study carries out three parts—Part Ι: To investigate the properties of nCa-MCFs-HP material and the formation of biomimetic crystallization in dentin tubule. We would analyze the interaction of tubule crystallization and biomaterials by using scanning electron microscope. The elution of dentin bonding agents and monomers through 0.2 mm dentin disc after nCa-MCFs-HP treatment would analyzed by UV-Vis spectroscopy and HPLC. Part ΙΙ: To evaluate the biocompatibility of nCa-MCFs-HP biomaterials, and to establish the in vitro deep dentin disc model. Part ΙΙΙ: To evaluate the pulp cell mineralization after nCa-MCFs-HP treatment. The results revealed that the nCa-MCFs-HP can form calcium phosphates crystallization in tubule. The biocompatibility of nCa-MCFs-HP was also confirmed by WST-1 and LDH test, which indicates no significant cytotoxicity, and lower cytotoxicity than the group of dentin bonding agents. The simulated deep cavity treating with nCa-MCFs-HP material can form a biomimetic crystalline barrier which may protect pulp cell from toxicity monomers released from composite resins and dentin bonding agents. ALP staining assay, ALP quantitative assay, and mineralization-related protein – DMP-1, DSPP expression further indicated the nCa-MCFs-HP treated dentin has the great help of the induction of pulp cell mineralization. Based on the given situation, we concluded that the nCa-MCFs-HP biomaterial has good biocompatibility, and the forming biomimetic crystallization protect layer could reduce the toxic monomers permeation, protect pulp tissues, and promote mineralization as a pulp capping material.
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陳瀅弘. "Performance and Reliability of Strained NMOSFETs with SiN Capping Layer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/94490529133954945153.
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碩士國立交通大學
電機學院微電子奈米科技產業專班
96
In this thesis, we investigated the characteristics of strained-channel NMOSFETs with different thickness of silicon nitride (SiN) capping layer deposited by plasma enhanced chemical vapor deposition (PECVD) system. We found that thicker SiN capping would result in higher tensile stress in the underlying channel and leading to a higher mobility. Therefore, higher performance enhancement was observed for devices with thicker SiN capping. However, the increased mobility and the SiN deposition process would aggravate the hot carrier reliability, resulting in the severest hot carrier degradation for the samples with the thickest SiN capping. The analysis of Fourier transform infrared spectrometer (FTIR) was also investigated. The extra Si-H bonds were observed, indicating that PECVD SiN indeed has abundant hydrogen species.
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Yu-ChihHsiao and 蕭有志. "Effects of constraint annealing and capping layer on Si/HfO2." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/91882188710484631989.
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碩士國立成功大學
電機工程學系碩博士班
101
In this thesis, the stress effect of HfO2 insulating layer within the MOS structure has been discussed. From the experiment result, we can see that the crystallization of HfO2 was enhanced by constrained annealing, which inhibited the formation of capping layer on HfO2. Therefore, the further discussion of capping layer on HfO2 would be discussed in details in the second part of this thesis. The experiment has shown that the compressive and tensile stresses have the similar effect to HfO2. The constraint stress inhibited further growth of the interfacial layer (IL) between HfO2 and Si, suppressing the IL-growth-induced Si outward emission. This fact was associated with atomic rearrangement that was induced during constrained annealing, resulting in the formation of a robust HfO2 layer with low oxygen vacancy. Such an HfO2 layer effectively suppressed the inward diffusion of oxygen, the IL growth and the Si out-diffusion. In addition, we can see evidence of the relationship of crystallization and the forms of SiO2 capping layer when HfO2 is mechanically constrained. During annealing, the growth of interfacial layer in Si/HfO2 led to an out-emission of Si from interface to film surface and self-formed a SiO2 capping layer. The crystallization of HfO2 film on Si substrate was suppressed due to the self-capping effect.
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Bin-Chan, Lin. "Effect of capping superconductive layer and MgO spacer on tunnel magnetoresistance." 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-3001200721411300.
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Zhang, En Hao, and 張恩豪. "The Study of Ge Schottky photodetector with a-Si:H capping layer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/29175864280667751531.
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碩士大葉大學
電機工程學系
98
In this study, reduction of dark current characteristics in the Ge-based Metal-Semiconductor-Metal photodetectors (MSM-PD) with and without hydrogenated amorphous silicon (a-Si:H) and/or with silicon dioxide (SiO2) passivation layer will be discussed. The a-Si:H and SiO2 layer were deposited by using plasma-enhanced chemical vapor deposition (PECVD) system. At 6V applied voltage, the measured dark current were 1.27×10-8 A, 2.14×10-3 A and 2.5×10-3 A, respectively, for the samples with a-Si:H passivation, without a-Si:H passivation, and with SiO2 passivation layer, respectively. Compared to the sample without a-Si:H layer, the dark current with a-Si:H passivated one was reduced about five orders. Such a result demonstrates that the a-Si:H exhibits passivation function on Ge surface. Additionally, we used above result to fabrication four structures of a-si:H capping leayer. The 850nm and 1310nm infrared laser light source with fixed power was used to irradiate these samples. It was found that four structures of optoelectronics characteristic by using 850nm and 1310nm infrared laser light source.
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Chen, Yu-Hung, and 陳玉鴻. "Study of SiGe Schottky Contact Photodetector With a-Si:H Capping Layer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/50073636344755163887.
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碩士大葉大學
電機工程學系碩士班
93
An amorphous silicon (a-Si:H) layer has been used to suppress the dark current for a SiGe Schottky photodetector. The a-Si:H was deposited onto undoped Si0.8Ge0.2 layer by using plasma enhanced chemical vapor deposition (PECVD) system, in which a thickness of 150 nm SiGe layer was grown onto p-Si substrate by using ultra-high vacuum chemical vapor deposition (UHCVD). Various metals, such as Au and Cr, and silicides have been employed to fabricate SiGe Schottky photodetector. In this study, Schottky barrier photodetectors with and without a-Si:H capping layer have been demonstrated. We found that the photodetector with a-Si:H capping could effectively suppress dark current than that without capping and this is attributed to higher barrier height due to the properties of high resistivity and bandgap for a-Si:H material. It was found that the photodetector with Cr Schottky electrode has a lower dark current than the one of Au electrode. With incident light wavelength of 1100 nm on 0V bias, the measured responsivity was around 0.155 and 0.775 A/W for without and with a-Si:H capping layer, respectively. Additionally, a low cost wavelength filter of Si0.8Ge0.2 photodetector has been proposed for the first time in our study. This filter was accomplished by simply inserting a thin a-Si:H layer onto Si0.8Ge0.2 film. The full width at half maximum (FWHM) has been narrowed by a half than that without a-Si:H capping.
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Kuo, Ying-Hua, and 郭穎華. "Effects of Ti and TiN capping layer on cobalt silicide formation." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/71932110130904675282.
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(9828488), Senanie Radampola. "Evaluation and modelling performance of capping layer in rail track substructure." Thesis, 2006. https://figshare.com/articles/thesis/Evaluation_and_modelling_performance_of_capping_layer_in_rail_track_substructure/13416674.
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"In the design of rail track structures where the subgrade cannot achieve the desired capacity, enabling the required standard of track geometry to be maintained for the speed, axle load and tonnage to be hauled, a capping layer of granular material is placed between the natural ground or the embankment fill material and the ballast to protect the underlying weaker layers. In spite of the important role played by the capping layer, very little research has been carried out on its performance. The current practice of design of the capping layer, therefore, is based on working stress philosophy where reduced levels of stresses are assumed not to degrade the subgrade. Even on tracks containing a thick ballast layer that ensures allowable levels of working stress the subgrade has been found to have permanently deformed. Design of capping layers based on plastic deformation, therefore, appears appropriate. This thesis aims at determining the load levels that cause detrimental plastic deformation in the capping layer. The suite of material properties that characterise plastic deformations of capping layer is neither readily available nor easily determined. This thesis proposes a cheaper method of evaluating a range of capping layer material properties using penetration tests on specimens contained in California Bearing Ratio (CBR) test moulds coupled with a finite element modelling based back calculation technique. The suite of material properties thus determined are used for the simulation of the behaviour of capping layers under the boundary and loading conditions similar to those in practice. The predicted results are validated using laboratory experiments on large size capping layer specimens." -- abstract
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Wei, Chun-Shing, and 魏忠信. "Study of SiGe Metal-Semiconductor-Metal Photodetector with a-Si:H Capping Layer." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/87968983143390144490.
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碩士大葉大學
電機工程學系碩士班
94
The SiGe badsed metal-semiconductor-metal photodetectors (MSM-PDs) has been fabricated in this work, in which the Si0.8Ge0.2 layer is grown onto n-Si substrate by ultra-high-vacuum chemical-vapor-deposition (UHV-CVD) system. In our structure, a thin hydrogenated intrinsic amorphous silicon (i-a-Si:H) layer is processed onto SiGe surface to suppress the dark current of this structure. The i-a-Si:H layer is deposited by using plasma-enhanced chemical-vapor-deposition (PECVD) system. The MSM-PDs without a have a high dark current of 6.58×10-3A at a bias voltage of 10 V, however, the dark current is only 2.16×10-7A for with a thin i-a-Si:H one. The photocurrent of sample with a thin i-a-Si:H is 2.51×10-5A, and thus a photo-to-dark current ratio (Iphoto/ Idark ) of 102 is achieved for 850 nm infrared laser illuminated Additionally，we try to deposit an oxide passivation layer between fingers on Si0.8Ge0.2 layer by liquid-phase-deposition (LPD) technique. Compared with the MSM-PDs without LPD oxide passivation layer , the dark current of MSM-PDs with LPD oxide layer is reduced from 1.73×10-4A to 4.93×10-5A at a bias voltage of 2 V, after annealing the dark current is reduced further to 1.67×10-5A.
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Yang, Shih-Chi, and 楊士碁. "Molybdenum Disulfide Thin Film Transistors with Graphene Contact and Al2O3 Capping Layer." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/55853367276306270092.
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碩士國立臺灣大學
電子工程學研究所
102
In the thesis, we mechanically exfoliated MoS2 nanosheet, checking their thickness by optical microscopy and atomic force microscopy. After choosing the nanosheet with an appropriate thickness, we fabricate MoS2 TFT with it. However, the MoS2-to-metal interface is strongly impacted by Fermi level pinning close to the conduction band of the MoS2, resulting in a large contact resistance. In view of this, we insert graphene between the metal and MoS2 to prevent Fermi-level pinning and to modulate the work function, resulting in a smaller Schottky barrier height. TFTs with graphene/metal hetero-contact performs better than those with only metal contact, achieving the best on/off current ratio of 5 order of magnitude and the mobility of 12 cm2/V-sec. . In addition, we tune the growth temperature of ALD-Al2O3 to achieve a uniform coverage on MoS2. Since physical adsorption is the dominant adsorption method at the MoS2 surface, growth at lower temperature helps attain a better coverage. When the temperature was down to 190°C and 170°C, we observed a uniform Al2O3 layer formed on MoS2 surface and no evident pinpoles were observed. Finally, we capped the Al2O3 layer grown at 190°C on our devices, the mobility can be enhanced to about 32 cm2/V-sec. The electrical properties of passivated MoS2 TFTs are stable despite the devices were exposed to atmosphere for 20 days.
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Tseng, Kuo-Hau, and 曾國豪. "Photo-Capacitance of Non-Relaxed InAs Quantum Dots with InGaAs Capping Layer." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/21424651150596516197.
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碩士國立交通大學
電子物理系所
100
Electrical and optical properties for relaxation and non-relaxation InAs quantum dots (QDs) with an InGaAs capping layer fabricated by molecular beam epitaxy (MBE) deposition, were studied. First, the properties of quantum states, defect states, and mechanism of electron emission in InAs QDs samples are studied by using capacitance-voltage (C-V) profiling, bias-dependent deep level transient spectroscopy (DLTS), transmission electron microscope (TEM), and photoluminescence (PL) measurements. Second, the bias-dependent sweeping rate affects electron emission from the defect state by DLTS spectra. An elevated capacitance is found at the temperature of 300K by C-V measurement with the variation of sweeping rate, suggesting a non-relaxation InAs QDs containing a deep defect. Third, the photo-capacitances for relaxation and non-relaxation InAs QDs are investigated by using C-V measurement under illumination with the variation of energy (0.7 ~ 1.56 eV). The three regions are considered the electron emission from the EL2 defect state and the deep defect state and carrier recombination in the energy-dependent photo-capacitance spectra for non-relaxation InAs QDs. The large difference of photo-capacitance for two samples is due to the concentration of EL2 defect states, suggesting the inter-diffusion with In and Ga atoms suppress the EL2 defect forming in the relaxation InAs QDs. In addition, an existence of the deep defect is confirmed in the PL spectra by using an excitation energy-dependent laser. By illumination energy of 0.8 eV, photo-capacitance originates from the electron emission of EL2 defect states, and the valley peak shift can analyze the mechanism of excess electrons emission from EL2 defect states in the carrier distribution profiling. As illumination energy is 1.17 eV, the recombination rate of excess carriers increases accompanying photo-capacitance decreases.
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Wen, Huang-Chun, and 溫凰君. "Ultra-Shallow Junction Formation for Nano MOS Devices Using Amorphous Silicon Capping Layer." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/80161201359276452221.
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碩士國立交通大學
電子工程系
90
In this thesis, we have proposed a new ultra-shallow junction formation method for nano-MOS technology applications. As device dimension scales down, the short channel effects become more serious. Formation of ultra-shallow junctions is essential to minimizing punch-through and short channel effects. This thesis presents a method to fabricate ultra-shallow junctions using present ion implantation and rapid thermal annealing techniques without requirement of low energy implant equipments. Diffusion from implanted amorphous silicon (DIA) is performed by junction implant through an amorphous capping layer; the amorphous layer thus acts as a surface solid diffusion source during annealing. A thin oxide is deposited to serve as etching stop layer beneath the amorphous layer. This bilayer amorphous-oxide structure enables easy removal of the amorphous layer and provides good process control and device reliability. By using amorphous silicon layer as the diffusion source for junction formation, implant defects are reduced. Defect-free ultra-shallow junctions can be formed. DIA junctions are also co-implanted with F to observe the effect of F on junction characteristics. Finally, DIA junctions combined with Ti capped Ni silicide processes have been fabricated. The DIA structure has been found to reduce periphery junction defects. These junctions exhibit good electrical and junction characteristics suitable for the future MOS technology.
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李健逢. "Electronic structure Properties and Protective Capping Layer Studies of MBE-Bi2Te3 Thin Films." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/58861295778073585334.
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碩士國立清華大學
先進光源科技學位學程
102
The epitaxial Bi2Te3 topological insulator (TI) thin films grown on sapphire (0001) by molecular beam epitaxy (MBE) were studied by using X-ray photoemission spectroscopy (XPS) and synchrotron radiation angle-resolved photoemission spectroscopy (ARPES). The Bi2Te3 films, grown at fixed substrate temperature with the different Te/Bi flux ratio for each samples, and used the XPS to calculate the chemical composition ratio. And sharp metallic states and Dirac cone were also observed by ARPES. Interestingly, we also observed that the doping level in Bi2Te3 films can be fine turned by varying the Te : Bi composition ratio systematically to form either p- or n-type films. The electronic properties of bulk Bi2Te3 crystals are usually dominated by electron donors, resulting in n-type conductivity. When the donors dominate, the Dirac point is buried deep below the Fermi level, which makes it difficult to characterize the topological transport properties and to develop topological devices that rely on the behavior of surface Dirac fermions. To compensate for the unintentional donors, a high-concentration of extrinsic dopants, for example, more than 0.67% Sn [13] or 1% Cd, [14] has been introduced into Bi2Te3. And the intrinsic doping is the other way, in principle, we can tuning the density of the anti-site defect by controlling the growth condition. The anti-site defect controlled by tuning the substrate temperature had been successfully demonstrated. In this work we tried another way to generate the anti-site defect, the variation of growth flux ratio(Te/Bi ratio) was tried to generate the atomic anti-site defect, and got the amount control.
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Hsieh, Yu-Lin, and 謝雨霖. "Device Characteristics and Hot Carrier Degradation of Strained NMOSFETs with SiN Capping Layer." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/68362437729759164603.
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碩士國立交通大學
電子工程系所
94
As the scaling of CMOS structure reaches its fundamental limits, the carrier mobility enhancement has been intensively pursued by introducing strain in the channel region. This has been demonstrated in strained Si devices on SiGe substrates by taking advantage of the lattice mismatch between Si and SiGe. Although biaxial tensile strained silicon has received considerable attention in the last decade as a technique for mobility enhancement, it has been proven to be difficult to implement because of misfit and threading dislocations, Ge up-diffusion, fast diffusion of S/D extensions, and high cost. In contrast, uniaxial strain can be more easily implemented by simple structure modification, thus avoiding the complex wafer fabrication, high cost, and defects of biaxial strain. Recently locally strained devices have emerged as the main technique for carrier mobility enhancement (e.g., SiN-capped devices). In this thesis, we investigated the impact of silicon nitride (SiN) capping layer and the associated deposition process on the device characteristics and hot-electron degradation of NMOSFETs. The SiN layer used to induce channel strain for mobility enhancement was deposited by low-pressure chemical vapor deposition (LPCVD). The deposition of the SiN would aggravate threshold voltage roll-off due to additional thermal budget and the strain effect. Besides, the device hot-electron degradation is aggravated by the SiN-capping.
32
Huang, Wa-Xiang, and 黃威翔. "Influence of ZnSe partial capping layer on ripening effect of CdSe quantum dots." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/48233418013828792298.
Full textAbstract:
碩士中原大學
應用物理研究所
94
We investigated the ripening properties of self-assembled 4.0 mono-layers (MLs) CdSe quantum dots (QDs) with ZnSe partial-capping and subsequent anneal of 2 minutes on 50 nm ZnSe buffer layer grown on GaAs (001) substrates by molecular beam epitaxy. Atomic force microscopy, photoluminescence (PL) and photoluminescence excition (PLE) were employed to study the surface morphology and optical properties of CdSe QDs with different ZnSe partial capping thickness. As ZnSe partial capping layer less than 4.0 MLs, the ripening effect will be enhanced with the thickness of capping-layer increased. Therefore, the dots sizes became larger and the peaks energy red-shifted were observed in PL spectra. On the contrary, as ZnSe partially capping layer more than 4.0 MLs, the ripening effect was suppressed with the thickness of capping-layer increased. Moreover, when the thickness of capping layer is higher than the dot height, such as 20 MLs, ripening effect disappeared. In addition, a simple relation between the partially capping thickness and the ripening enhancement factor (C) was introduced. Moreover, PLE measurements indicated that the quality of the interface between QDs and cap layer could be improved by the ripening process.
33
Lin, Yen-Chun, and 林妍君. "The properties of strain induced bimodal InAs quantum dots with InGaAs capping layer." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/52095913057864829793.
Full textAbstract:
碩士國立交通大學
電子物理系所
99
In this work we study a method for controlling of the structure of the InAs quantum dots (QDs) with InGaAs capping layer fabricated by molecular beam epitaxy (MBE) deposition. When the InAs deposition exceeds of 3 ML, strain in the InAs QDs is relaxed. At the same time, the bimodal QDs start to form. The characteristics of the bimodal QDs are studied by optical and electrical measurements. The interfaces of the GaAs buffer layer and the InAs QDs contain misfit dislocations as determined from transmission electron microscopy (TEM). The photoluminescence (PL) spectra of the bimodal QDs shows an abnormal PL blueshift of 70 meV. We observe the existence of two types of QDs in the strain-relaxed QDs system: a low energy QD family whose strain is relaxed by the generation of misfit dislocations, and a high energy QD family whose strain is mainly relieved by indium outdiffusion. The effect of interdot carrier transfer on temperature dependent PL is investigated. The integrated-PL intensity of low energy QDs shows two regimes (i) an unusual increment begins about 110 K (ii) and then drops rapidly above 160 K. The full width half maximum (FWHM) of the high energy QDs first decreases about 110 K and reaches a minimum value at about 200 K. The phenomenon can be attributed to the carrier transfer between the bimodal QDs from the high to the low energy QDs through the InGaAs quantum well. Accordingly the carrier emission time determined by G-F measurement exhibits a V-shape versus the similar temperature dependence (78 K~140 K) due to carrier transfer between bimodal QDs in 3.3 ML sample. Based on G-F data analysis, the mechanism of carrier emission in a large electric field is likely phonon-assisted tunneling when temperature increased. Furthermore, we investigate the energy level distribution and defect states in the QD sample by electrical measurements under optical ionization. The variation of electron emission time under illumination suggests the emission rate is proportional to the depletion region, concentration, and electric field.
34
Lin, Shao-Yang, and 林少洋. "Optoelectronic characteristics study of InGaAs quantum dot solar cell with AlGaAsSb capping layer." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/2x2mz4.
Full textAbstract:
碩士元智大學
電機工程學系丙組
107
This study investigated the effects of indium gallium arsenide (InGaAs) quantum dots (QDs) covering aluminum gallium arsenide antimony (AlGaAsSb) on the optoelectronic properties of the future solar cells. Since the QD emission wavelength is positively correlated with the indium-containing composition of the quantum dot structure, the carrier limitation, and the internal compressive stress, the shorter emission wavelength indicates the lower material structural stress and the epitaxial defects that may occur, and the preferred material. quality. In order to avoid quantum dot defects caused by excessive stress, the preparation of optimal luminescent wavelength quantum dots has a considerable influence on the efficiency of future quantum dot solar cell devices. This research direction is based on the study of 6.6ML InGaAs quantum dots. For the further structural design of the capping layer, the difference of the presence or absence of aluminum between the antimony-containing aluminum capping layer and the antimony-containing capping layer is compared.The quantum dots with the AlGaAsSb capping layer have a distinct first excited state, and the quantum dot photoluminescence intensity is significantly better than that of the antimony-containing cladding layer (2 nm GaAsSb). The possible reason is that the aluminum-containing cladding layer can improve the carrier confinement of the QD structure, so the PL luminous intensity of QD can be increased. In addition, the aluminum-containing structure can reduce the In-Ga intermixing phenomenon between the quantum dots and the capping layer, so that the longer wavelength of the emission is extended to 1210 nm, and the quantum carrier has a special carrier limitation, and the first excitation can be exhibited by the spectrum. This quantum dot structure of good optical properties is expected to increase the open circuit voltage of aluminum-containing quantum dot solar cell devices and their overall device conversion efficiency.
35
Tsai, Tzu-I., and 蔡子儀. "Impacts of a Buffer Layer and Hi-wafers on the Performance of Strained-channel NMOSFETs with SiN Capping Layer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/73745391359072300590.
Full textAbstract:
碩士國立交通大學
電子工程系所
95
In this thesis, the effects of both the Si3N4 layer capping over the gate and the hydrogen-blocked TEOS buffer layer inserted prior to the Si3N4 deposition, on the NMOS device characteristics as well as the correlative hot-electron degradation were investigated. The devices were built on two kinds of the substrates, namely, Cz and Hi-wafers. Besides, the influences of the F channel implant on both fundamental performance and the related reliability of the fabricated devices were also explored. For devices on the Hi-wafer, the buffer layer would not degrade the device performance. On the contrary, the buffer layer for devices built on Cz wafers would degrade the performance. Such disparity is attributed to the better surface quality of the Hi wafers. On the other hand, the F channel implant draws significant impacts on the device performance for devices built on Cz wafers, such as degradation of Gm and S.S. When Hi wafers were used as the starting substrates, such negative impacts could be relaxed. These findings highlight the merits of Hi wafers over that of Cz wafers. The thermal budget associated with the deposition of the Si3N4 capping layer could help redistribute the segregated boron dopants in the channel and alleviate the reverse short-channel effect, although the poly-depletion effect becomes worse. More importantly, we found that hydrogen species is the primary culprit for aggravated reliabilities in strained devices. The TEOS buffer layer could effectively block the diffusion of hydrogen species from Si3N4 into the channel and interface of Si/SiO2 during the Si3N4 deposition and subsequent thermal cycles. The hot-electron degradation is adversely affected when the Si3N4 capping layer is deposited over the gate as compared with the control samples, regardless of the types of wafers. When a TEOS buffer layer was inserted prior to the Si3N4 deposition, although still worse than the control ones, significant improvement in resistance to the hot-carrier degradation over that without buffer is achieved. Besides, with the assistance of the F channel implant, the hot-carrier degradation of devices is obviously improved.
36
蔡秉霖. "Influence of capping layer on magneto-optical kerr effect in magnetic sheet-film systems." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/06008240754030579930.
Full textAbstract:
碩士國立彰化師範大學
光電科技研究所
96
The objective of my thesis is mainly to investigate influence of capping layer on magneto-optical Kerr effect in magnetic sheet-film systems. To prevent the unwanted oxidation of the magnetic layer, we overlay the capping layer on the optically magnetic layer. With a capping layer, the magnetic character of the magnetic layer didn’t change and the capping layer increase intensity of the kerr rotation. We change three materials of capping layer. The three materials are SiNX, MgO, and Ta. With change the material of the capping layer, we also change the depth of every capping layer. Otherwise, we change the different incident angle. When the incident angle is sixty, the intensity of the kerr rotation present the best result. We first discuss the the capping later of SiNX and MgO which both are insulated material. With the depth of capping layer from 0nm to 60 nm, the capping layer increase the intensity of kerr rotation by the thin-film system. With the depth of capping layer from 60nm to 100 nm, the capping layer decrease the intensity of kerr rotation by the thin-film system by the bulk material system. Secondly, the capping layerof Ta is metal material, the capping layer decrease the intensity of kerr rotation by the thin-film system by the skin effect.
37
Chen, Liang-Hao, and 陳良豪. "High Performance Amorphous In-Ga-Zn-O Thin Film Transistor with Si Capping Layer." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/15813482316844577859.
Full textAbstract:
碩士國立交通大學
光電工程學系
100
With a high mobility (>10 cm2/Vs) than conventional amorphous silicon semiconductor and a low operating voltage (< 5 V) and small sub-threshold voltage swing, amorphous In-Ga-Zn-O thin-film transistors (a-IGZO TFTs) draw a lot of attentions. Besides, due to a low temperature process and high transparency, a-IGZO TFTs is suitable to develop on flexible displays. However, when a-IGZO TFTs are developed for low-power consumption, high-frequency operating of circuit, improved electron mobility and a low parasitic capacitance are required. In this study, we found the carrier mobility significantly increase by a silicon capping layer on the back channel. We presume that the oxygen in IGZO films be captured by silicon and transfer to the silicon surface or bulk. Therefore the oxygen vacancy is created to dramatically increase the carrier concentration and leaded the mobility significantly improved. Hence, we propose a structure with silicon capping layer onto the active layer of bottom-gate a-IGZO TFT to provide a powerful solution of enhancement of device performance that would not cause current leakage and performance degradation. The method of Si capping layer is a simple and effective approach to fabricate a feasible metal oxide transistor. Besides, we also use co-sputtered a-IGZO/IZO to improve the mobility, incorporating with the Si capping layer and changing the capping ratio or position to find the physics behind. Moreover, we try to passivate the device without changing the characteristics to improve the stability so that we could apply to the present display technology.
38
Lin, Grow Chen, and 林國丞. "Characteristics of metal/insulator/Si Structures of Gate dielectric for Capping Layer with ZrN." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/14695466644617192667.
Full textAbstract:
碩士亞洲大學
光電與通訊學系
102
In this study, the use of experiment planning in the silicon substrate by sputtering (co-sputtering) deposition of 7 nm insulating layer of hafnium and zirconium oxide (HfZrO4), then by sputtering and high-power magnetron sputtering (HIPIMS) deposition a layer of 1.5 nm layer of a metal cap (Capping layer) of ZrN and then deposition a metal layer of titanium (TiN), and then the sample were then made a rapid thermal annealing (RTA) of 550 °C 、700 °C、 850 °C, after deposition aluminum (Al) as an electrode, so a gate electrode. Next on using by the current - voltage (I-V), capacitance - voltage (C-V), low-temperature measurements, chemical analysis cushions spectrometer (XPS), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), etc. analysis of the electrical and physical properties of the cap layer made using different deposition methods capacitor. The results show, Deposition of ZrN capping layer (1.5 nm) of HIPIMS in ZrO2 based on high dielectric constant film, found a smaller than conventional PVD C-V hysteresis curve in the MIS structure, higher capacitance values Dit lower performance than the conventional PVD Dit as small as about 4 times.
39
Hou-Ru, Li. "Characteristic of 10 periods SLS LED with Si0.8Ge0.2 capping layer for 1.3 ~1.5 um wavelength." 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-3006200518434700.
Full text
40
Li, Hou-Ru, and 李後儒. "Characteristic of 10 periods SLS LED with Si0.8Ge0.2 capping layer for 1.3 ~1.5 um wavelength." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64331038214875194231.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
93
The advantage of the optoelectronic component of silicon germanium is fully compatible with the Si-based microelectronic chips. In addition, the progress of the growth techniques for quantum heterojunction structure is in advanced. So the heterojunction structure of silicon germanium is studied far and wide in recent years. In this thesis, the light-emitting diodes (LEDs) with multi-periods of Si/SiGe superlattice operating at room temperature for 1.3-1.4μm emission wavelength are reported. We design a ten periods Si/SiGe superlattice structure that is grown by UHV/CVD system in this thesis, and two materials of Si and SiGe bulk are grown in P+ doped region, called sample-A and sample-B separately. Then we analyze the influences of the P+ doped region on electroluminescence characteristics, especially the electroluminescence (EL) spectra. According to experimental results, we find that because conduction band of SiGe is higher than that of Si, the electrons that diffuse to P side will be blocked and accumulate in the region of Si buffer and superlattice, and causes the electrons density grow up. Besides, the valence band of SiGe is also higher than Si, so that will block a part of injection holes, causes holes accumulate in the regions of P+ doped SiGe and superlattice at low temperature, and the light emitting from SiGe bulk and superlattice only can be observed. Holes aren’t easily confined in superlattice and the valence band of the SiGe bulk at room temperature, so we can observe stronger Si light emitting in sample-B than sample-A by the effect of the P+ doped SiGe region. Conclusively, the P+ doped SiGe layer can suppress the Si light emitting so we can observe the light emitting from SiGe bulk and superlattice at low temperature, and it can enhance the Si light emitting at room temperature.
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Ting, Yu, and 丁昱. "Using Activated Carbon/Clay-Based Thin Layer Capping for Mercury-Contaminated Sediment Remediation: Microcosms Study." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/tu2tvt.
Full textAbstract:
碩士國立臺灣大學
環境工程學研究所
107
The breakthrough of in-situ thin layer capping technology in recent years has shed light on the remediation of Hg-contaminated sediment and provides a promising alternative besides traditional dredging. In this thesis, the plausibility of several activated carbon (AC)/clay-based thin layer caps were demonstrated in two microcosm studies. In the first study, a lab-synthesized sulfurized activated carbon (SAC) performed greater sorption affinity to both aqueous Hg2+ (KD=9.42×104) and MeHg (KD=7.66×105) compared to those for raw activated carbon (KD=3.69×104 and 2.25×105, respectively) in isotherm adsorption tests. However, AC appeared to have greater sequestration ability than SAC in Hg-spiked sediment (14.2‒235.8 mg-Hg/kg), with the optimistic dosage of 3wt% AC causing reduction of THg with 99.88%. It may suggests that possibly formed nano-HgS particles could be released thus elevates the porewater Hg when SAC existed. Also, a 83-d trail of up-flow microcosms was demonstrated with various caps (SAC + bentonite, SAC + clean sediment, and AC + bentonite) and all observed significant inhibition of both THg and MeHg. In the second study, a horizontal-flow microcosm with lab-made vibration system was designed to evaluate the capping efficiency during turbation events. AC/clay-based caps with clay combinations were applied to actual Hg-contaminated estuary sediment (76.0±2.59 mg-Hg/kg). The caps with AC + bentonite and AC + kaolin were efficient in reducing both total mercury (THg) and methylmercury (MeHg) concentrations in overlying water by 75−95% and 64−98%, respectively in the later stage of 75-d operation. In contrast, the AC (3%) + montmorillonite (3%) cap did not show a significant reduction on THg and MeHg in overlying water, probably due to the unstable, suspension property of montmorillonite. The stable caps showed higher resistance to Hg breakthrough under occasional turbation events; however, a labile cap appeared to have dramatic Hg breakthrough when turbation occurred. It is therefore essential to note that with unstable caps, turbation events may result in unwanted secondary resuspension of contaminants.
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Alkhaldi, Huda. "Porosity in Group IV-IV and III-V Alloys Induced by Ion Irradiation in the Nuclear Stopping Regime." Phd thesis, 2016. http://hdl.handle.net/1885/116164.
Full textAbstract:
The motivation for this study is twofold: i) from a fundamental
perspective, to further investigate and understand porosity in
group IV-IV and group III-V semiconductors and its dependence on
ion fluence, temperature, and stoichiometry using
multi-characterization techniques including electron microscopy
(SEM and TEM), surface profiling, Rutherford backscattering
(RBS), Raman Spectroscopy (RS) and Small Angle X-ray scattering
(SAXS); and ii) to assist in opening up potential exploitation in
applications such as lithium ion batteries as an anode, in gas
sensors, in thermoelectrics, and in optoelectronics
applications.
Firstly, pore formation in Ge and Si1-xGex alloys (x= 0.83, 0.77,
and 0.65) was investigated under keV Ge ion irradiation. The
initiation of porosity and the evolution of near-surface
microstructure highly depend on ion fluence and irradiation
temperature, as well as the substrate stoichiometry. Porosity is
only observed up to 23 % Si in the alloy, higher Si concentration
does not result in porosity for samples implanted at room
temperature even when the ion fluence is increased to above 1018
ions/cm2. Additionally, in order to produce porosity in Ge and
Si1-xGex alloys, the matrix has to be rendered amorphous during
ion bombardment prior to porous formation. Increasing the Si
content leads to an increase in the threshold condition for
porosity, with higher ion fluence and higher implantation
temperature required. Moreover, we observe at a 35 % Si content
an unusual surface topography at elevated temperatures, which is
largely irreproducible. This is explained in terms of oxidation
and contamination due to poor vacuum in the implant chamber.
Although, the observation of porosity in Ge is dominated by
swelling of amorphous Ge, in Si1-xGex alloys preferential
sputtering and segregation of Si/Ge play a significant role. All
the data suggest a model of vacancy migration and clustering in
an amorphous matrix is appropriate to explain pore formation.
SAXS provides complementary information to electron microscopy,
giving an estimation of pore size and sidewall thickness. Indeed,
SAXS provides a better statistical average of the
radius of pore features as it gives the average of the entire
bulk porous structure compared with only surface sensitivity of
SEM. We find that using an appropriate core shell cylinder model
to fit SAXS data, there is good agreement with cross-section TEM
(XTEM) results. Results show that the pore size increases with
ion fluence until the porous structure fully develops, and then
no longer depends on ion fluence. Some differences in pore size
between the different techniques is observed and these are
explained as follows: SEM images consider only surface effects
while XTEM and SAXS take into account the underlying bulk.
However, both pore radii and sidewall thicknesses increase at
elevated temperature by 8 and 2 nm, respectively, as expected as
the point defect diffusivity increases with temperature.
The third part of the thesis investigates the effect of a cap
layer of SiO2 on pore formation. When porosity is observed, a cap
results in a more developed and well-ordered porous layer
compared to uncapped samples. This is explained in terms of
suppression of sputtering in a capped sample and the resulting
protection to the matrix, hence porosity becomes uniform and more
developed. For samples implanted below room temperature, the
porosity is completely suppressed by a cap. A large occasional
void with a mostly intact surface devoid of pores is observed.
When a porous layer does not form at higher temperatures there is
a continuous amorphous Ge layer denuded of pores formed directly
under, and in contact with, the cap. Interestingly, this layer
remains constant at about 8 nm in thickness regardless of the ion
fluence and temperature. Different possibilities that could
explain the formation of this barrier layer are discussed.
Firstly, ion irradiation can induce intermixing of O and Si from
the cap with the underlying Ge as shown by an x-ray elemental
distribution map and this could inhibit vacancy clustering and
pore formation. However, this explanation is not the whole story
since it would be expected that the barrier layer thickness
should increase with ion fluence but the barrier layer thickness
is always constant. A more reasonable explanation for a barrier
layer denuded of pores is based of viscous flow of amorphous Ge
under ion irradiation and the wetting of the cap to minimize
interfacial free energy. In addition, a cap layer on Si0.17Ge0.83
alloy always suppresses the porous structure. This may indicate
the importance of preferential sputtering in inducing porosity in
the alloy when a cap is not present, whereas the cap layer
prevents sputtering and hence porosity.
The last topic covered in this thesis is porosity and void
evolution in GaSb and GaAs1-xSbx alloys (x=0.75, and 0.50) under
the same implantation conditions as for Ge. Compared to GaSb
behaviour, GaAs0.25Sb0.75 shows small swelling with void
formation and sputtering both playing important roles. The
formation of voids is strongly depending on ion fluence,
temperature and stoichiometry. Indeed, the transformation from
crystalline to amorphous
xiii
and to void formation occurs at the same ion fluence. For
GaAs0.5Sb0.5 no void formation was observed, only the formation
of an amorphous layer and associated significant sputtering.
43
Chiang, Chun-Te, and 江俊德. "Study of Simulation on Lateral Grain Growth of Poly-Si Enhanced by Capping Layer and Microstructure." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/49380484844731811444.
Full textAbstract:
碩士國立交通大學
顯示科技研究所
96
In this thesis we simulate the heat transfer inside the a-Si thin film after KrF laser annealing. And by defining latent heat process region, the temperature distribution among the samples can be successfully measured. Not concerning nucleation effect, the recrystallization time becomes longer with the solidifying duration. We find that the thickness of SiO2 capping layer has an optimized value 100nm with and without trench, and that of SiNx capping layer thicker than 100nm has better performance on solidifying duration compared with the same thickness of SiO2 capping layer. We simulated the trench-assisted ELA. And we find out its optimized trench depth, 300nm, and its smallest separation, 2μm. It is proved that trench-assisted position-control ELA can induce lateral grain growth by observing the isothermal diagram. By recording the movement of the 1350K isothermals, we can calculate the isothermal moving velocity, namely solid-liquid interface velocity. Finally, we can estimate the grain size from a trench to one side is about 3μm for an optimized condition. In a word, utilizing a trench can induce about 6μm lateral grain growth.
44
Hsu, An-Chia, and 許安佳. "The Effect of Short-Chain Thiol Capping Layer on Optical Properties of CdSe/ZnS Quantum Dot." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/96407356917195747018.
Full textAbstract:
碩士國立交通大學
光電工程學系
100
The optical property analysis of short-chain thiol-containing molecules capping on CdSe/ZnS quantum dots (QDs) is reported. The electronic and optical properties of QDs are closely related with the highly surface-to-volume ratio and their surface electronic structure. Here we used core/shell QDs with some thiol molecules including β-Mercaptoethanol(BME), 3-Mercaptopropionic acid (MPA), and 1-propanethiol(NPM) to examine the effect of QD surface-thiol interaction of defect sites in short (immediately) and long (24 hr.) aging time. A comprehensive study of ultrafast spectroscopy, up conversion fluorescence, and temperature-dependent photoluminescence was used to clarify the function of thiols on QDs surface. We found the thiol molecules interact with QD only by weak coordination-type bonds through the sulfur lone-pair electrons. The thiol molecules can passivate the surface of QDs by preventing core electron from defect sites on the surface thus enhance PL intensity. While the strong covalent-type bonds are formed as thiol turn to thiolate through the long time incubation, new hole traps would be produced thus PL intensity quench. Thiol-containing molecules under investigation show different performance, which attribute to anti-oxidation, dissociation ability and second-order oxygen of the thiols. Finally, we found that the surface passivation occurs as long as the QDs are surrounded with negative charges since thiol-/-dithiol molecules have sulfur lone-pair electrons. That is the main reason why thiol-molecules usually apply to exchange ligands on the QDs surface.
45
Fu, Sheng-Chun, and 傅聖峻. "Effect of capping carbon layer on grain partition of FePt films on MoC+C/CrRu/glass." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/73320409153119776071.
Full textAbstract:
碩士國立中興大學
材料科學與工程學系所
103
Capping C layer with various thicknesses were sputtered on FePt/MoC/CrRu/glass at room temperature and post annealed from 190-365oC. The optimal magnetic property was obtained at 2 nm thick C layer annealed at 268oC and used to discuss FePt thickness effect. The FePt films with thickness of 4-10 nm were deposited on MoC/CrRu at 425oC by using magnetron sputtering. The MoC intermediate layer was epitaxially grown on the (200) textured CrRu seed layer and the FePt film was prepared on (200) textured MoC at 425oC. The FePt film shows strong (001) texture and out-of-plane coercivity of 7.5 kOe has been demonstrated in 10 nm thick FePt film. After capping 2 nm thick C layer and post annealed at 268oC, the out-of-plane coercivity was increased to 10 kOe in 6 nm thick FePt. From microstructure, the FePt grains were distributed in- or between- islands like structure and further separated by excess carbon from capping carbon layer and MoC intermediate layer. Thinner FePt film was more separated by excess carbon and shown higher coercivity.
46
Chang, You-Cheng, and 張祐誠. "The Influence of Strain Relaxation on the Properties of InAs Quantum Dots with InGaAs Capping Layer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/33058482015554022724.
Full textAbstract:
碩士國立交通大學
電子物理系所
98
In this study, we analyze the optical and electrical properties of the strain-relaxed InAs/InGaAs quantum dot (QD) samples with two different InAs deposition thicknesses, 3.06 and 3.3 ML, and discuss the influence of strain relaxation on the InAs QDs with InGaAs capping layer. While the strain relaxation is observed from the photoluminescence (PL) spectra of both QD samples, the carrier emission rate from the QDs, which can be obtained from the capacitance-voltage (C-V) and admittance (C-F) measurements, is much slower in the 3.3 ML sample than that in the 3.06 ML sample. It is attributed to the different defect concentration of two samples, estimated from deep-level transient spectroscopy (DLTS) measurements. The C-V simulation demonstrates the background concentration in the bottom GaAs is lowered by the defect. From the PL spectra and transmission electron microscopy (TEM) data of the 3.06 ML sample, we discover there are bimodal QDs in the samples. One of the QD families is strain-relived by indium out-diffusion, and the low-energy QD family is strain relaxed by the generation of misfit defect. PL properties of the 3.06 ML sample are studied as a function of temperature from 10 to 300 K. At about 140 K, an enhancement of the integrated PL intensity of the low-energy QDs and a decrease of the FWHM of the high-energy QDs are observed. These abnormal temperature behaviors are attributed to the carrier transfer from the high-energy QD family to the low-energy one. From the C-F measurements of the 3.3 ML sample, the interdot carrier transfer can be seen as the electron emission rate from the QDs exhibiting an unusual reduction at about 140K. Furthermore, the electron emission of the QD samples under illumination is investigated. During illumination, more electrons are injected into the QDs. The electron emission rate becomes faster due to the amount of electron on the conduction band is increased.
47
KUN-I, CHOU, and 周坤億. "The Investigation of GeO Capping layer on TiO2 Based and PZT Based Resistive Random-Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/01913161129551921833.
Full textAbstract:
博士國立交通大學
電子工程學系 電子研究所
102
With the arrival of Digital Mobile Life, the demands for nonvolatile memory (NVM) have significantly increased, such as mobile phones, digital cameras and portable devices. NVM technology has been developed to obtain high speed, high density and low power consumption. But, when the technology node continuously scaled down, the flash memory faces the challenge of retention drop caused by thin tunneling oxide. During long-term operation, the thickness of tunneling oxide below 10 nm will cause the charge lost in floating gate due to direct tunneling current or defects formed in the tunneling oxide. Therefore, several types of NVMs such as ferroelectric random access memory (FeRAM), magnetic random access memory (MRAM), and resistive random access memory (RRAM) are being investigated. There are many candidate materials for RRAM application including perovskite materials such as Pr0.7Ca0.3MnO3, PbZr0.5Ti0.5O3, SrZrO3, SrTiO3, and binary metal oxides such as NiO, TiO2, HfO2, Al2O3, and HfON. Such a memory application should have the merits of low power consumption, compatibility of the current complementary metal oxide semiconductor (CMOS) process, high-speed operation, high scalability, and simple metal-insulator-metal (MIM) tri-layer structure. The resistive switching mechanisms are attributed to the formation and rupture of the conducting filaments, which are related to trapping/detrapping, reoxidization/reduction, and Mott transition performed by O2− migration. Moreover, the stochastic formation and rupture of the filaments cause the fluctuation of the operation voltages and the memory states during continuous switching cycles, which may lead to severe control and readout problems. First of all, we have fabricated the Ni/GeOx/PbZr0.5Ti0.5O3/TaN resistive switching memory. Under unipolar-mode operation, the bilayers Ni/GeOx/PZT/TaN RRAM shows a large resistance window of >102, 85℃ retention, and a good DC cycling of 2000 cycles, which are significantly better than those shown by the single-layer Ni/PZT/TaN RRAM without the covalent-bond-dielectric GeOx . Next, to further improvement the distribution, we use GeOx with TiO2 layer to form Ni/GeOx/TiOx/TaN resistive random access memory for better device-to-device distribution and retention. This RRAM device shows low 30μW switching power (9μA at 3V; −1μA at −3V), 105 cycling endurance and good retention at 85 oC. To compare the different covalent bond dielectric with GeO, we fabricated AlOx/TiOx and GeOx/TiOx resistive random access memory at room temperature. The AlOx/TiOx and GeOx/TiOx RRAM exhibit similar set/reset powers and switching window, but the AlOx/TiOx RRAM shows much poor data retention and poor switching uniformity as compared to the GeOx/TiOx RRAM. In retention test, AlOx/TiOx RRAM presents poor 60 oC data retention due to high currents for high resistance state (HRS) with low activation energy (Ea) of only 0.4 eV, which is much lower than 0.52 eV of GeOx/TiOx RRAM. Finally, to avoid the degradation of the GeO layer caused by hydraulic in atmosphere, we fabricated Ge-SiO resistive random access memory to achieve simple structure of single layer, high speed operation of 60s for 104 cycling endurance and good retention at 85 oC.
48
Lin, Yan-Wen, and 林彥文. "A Study of Photoelectrical Characteristics for Transparent Organic Light-Emitting Diodes Based on Various Capping Layer Materials." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/64946817642296559941.
Full textAbstract:
碩士國立中正大學
光機電整合工程所
94
Transparent organic light-emitting devices based on various capping layer materials were deposited on Indium tin oxide (ITO) substrate by high vacuum evaporator system. In our study, the device configurations of transparent OLED using multilayer structure were ITO/m-MTDATA (500 Å)/NPB (600 Å)/Alq3 : C545T (100 Å)/Alq3 (900 Å)/Sm (350 Å)/ with various capping layers materials and thicknesses. The luminance performance of transparent organic light-emitting diodes (TOLEDs) with four different capping layer materials including zinc selenide (ZnSe), tungsten oxide (WO3), tellurium oxide (TeO2), and silicon oxide (SiO) is investigated. The results show that the performance of TOLED using WO3 as capping layer is superior to others for two possible reasons. One is higher optical transmittance of WO3 and hence less optical loss. Another is less optical dispersion due to flatter surface of WO3. It is also found that luminance of TOLEDs can be increased by adding capping layer on metal cathode.
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Lee, Kai-Hsuan, and 李凱璿. "Fabrication and Investigation of Nitride-based Metal-Semiconductor-Metal Photodetectors by Using Capping Layer or Recessed Electrodes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/55547636348864996333.
Full textAbstract:
碩士國立成功大學
微電子工程研究所碩博士班
95
The objective of this research is to design the appropriate device structure for nitride-based metal-semiconductor-metal (MSM) photodetectors to improve the device performances, including the suppression of the dark leakage current or the enhancement of speed, efficiency, and photoresponse of the photodetectors. The structure of nitride-based MSM photodetectors were epitaxied on sapphire substrate by metal-organic chemical vapor deposition system (MOCVD). The fabrication and characterization of the MSM photodetectors were also employed in our experiments. To achieve a GaN-based high performance MSM photodetector, it is critical to reduce the leakage current, which result from the defects in the film. However, the large differences in lattice constant and thermal expansion coefficient between GaN and sapphire inevitably lead to high dislocation defect density in the GaN epitaxial layer. We adopted a low-temperature (LT) grown AlN or an un-activated Mg-doped GaN capping layer onto the GaN active layer to solve this problem. Compared with conventional MSM photodetectors, we effectively suppressed dark leakage current and achieved larger UV to visible rejection ratio from the photodetectors with LT-AlN or an un-activated Mg-doped GaN capping layer. This result could be attributed to the thicker and higher potential barrier and effective surface passivation after inserting LT-AlN or an un-activated Mg-doped GaN capping layer. On the other hand, the efficiency and speed of the photodetectors are key points to judge the detectors between good and bad. For this reason, we designed the recessed electrodes configuration to reduce the transit time of photogenerated carriers and enhance the efficiency and speed of InGaN-based MSM photodetectors. From device measurement results, it was found that measured photocurrent and photocurrent to dark current contrast ratio were both much larger for the MSM photodetectors with the recessed electrodes. The responsivity and external quantum efficiency of the detector with recessed electrodes were also found to be larger than conventional one.
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詹凱翔. "A Study of Drive Current Enhancement Methods and Relability Issues of Strained NMOSFETS with PECVD SiN Capping Layer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/76901152570310353544.
Full textAbstract:
碩士國立交通大學
電子工程系所
95
Recently locally strained devices have emerged as the main technique for carrier mobility enhancement (e.g., SiN-capped devices). In this thesis, we investigated the impact of silicon nitride (SiN) capping layer and the associated deposition process parameters on the device characteristics and hot-electron degradation of strained NMOSFETs. The SiN layer used to induce channel strain for mobility enhancement was deposited by plasma-enhanced chemical vapor deposition (PECVD) by varying the flow rate of N2, while fixing the flow rate of SiH4 and NH3, to adjust the tensile stress of SiN film. For comparison, we also fabricated devices with compressive SiN capping layer using another PECVD system. We confirmed that the electrical characteristics of devices with tensile SiN capping layer will be improved. In contrast, the compressive SiN capping layer will degrade the device performance. We also found that the deposition of the SiN does not worsen the poly-depletion effect due to the light thermal budget. Furthermore, although the device hot-electron degradation is aggravated by the SiN capping layer, the degradation can be alleviated by increasing the flow rate of N2. We thus conclude that the electrical performance and reliability can both be improved by increasing N2 flow rate for NMOSFET with tensile SiN capping.