Thèses : « Magnesium oxide thin film »

1

Wang, Chao-Hsiung. « The growth of thin film epitaxial oxide-metal heterostructures ». Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368667.

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Dyachenko, A. V. « Spray pyrolysis deposition of magnesium oxide thin films ». Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/34844.

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Magnesium oxide seems to be a good candidate regarding its bulk properties: large band gap (7.8 eV), high thermal conductivity and stability and an alternative dielectric to silicon dioxide (SiO2) to reduce the electric field in capacitive networks. MgO, widely used as a substrate for high-temperature superconductor films deposition, has attracted much attention due to its low dielectric constant, low dielectric loss, and less mismatch with YBCO films. With a low dielectric loss, MgO shows a wide application in microwave devices. Due to its low refractive index, MgO is especially a suitable buffer for epitaxial optical waveguide films. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34844

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Hlaing, Oo Win Maw. « Infrared spectroscopy of zinc oxide and magnesium nanostructures ». Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/w_hlaingoo_121107.pdf.

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4

Bittau, Francesco. « Analysis and optimisation of window layers for thin film CDTE solar cells ». Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/32642.

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The work presented in this thesis focuses on the investigation and improvement of the window stack of layers for thin film CdTe solar cells fabricated in the Center for Renewable Energy Systems Technology (CREST) laboratories. In particular the aim was to change the standard structure including TCO, high resistive transparent (HRT)layer and CdS which is limited by the low transparency of the CdS layer, to a better performing one. The first result chapter of the thesis describes the study of ZnO HRT layers. ZnO thin films were deposited by radio frequency (RF) magnetron sputtering with different structural, optical and electrical properties which were characterized by X-ray diffraction, electron microscopy, spectrophotometry, Hall Effect method and 4-point probe. ZnO films were then incorporated in CdTe solar cells with the structure: FTO/ZnO/CdS/CdTe/Au back contact and the performance of these devices were compared with the film properties to single out trends and identify optimal film characteristics. By varying the deposition pressure of ZnO films, it was possible to increase their transparency and significantly increase their resistivity. While better transparency positively affected the solar cell current density output and efficiency, the resistivity of ZnO films did not show any clear impact on device efficiency. By increasing the deposition temperature the ZnO film grain size was increased. Increased FF was observed in devices incorporating ZnO layers with bigger grains, although this gain was partially counterbalanced by the Voc degradation, leading to a limited efficiency improvement. Finally the addition of oxygen had the main effect of increasing the resistivity of ZnO films, similarly to what happened with the increase of the sputtering pressure. In this case however, an improvement of FF, Jsc and efficiency was observed, especially at an O2/Ar ratio of 1%. By simulating the solar cells behavior with SCAPS-1D, it was found that these performance change can be explained by the variation of interface properties, precisely the amount of interface defects, rather than by bulk properties. The study presented in the second result chapter focuses on magnesium-doped zinc oxide (MZO) and the variation of its energy band structure. MZO was initially used as the HRT layer within a solar cell structure: FTO/MZO/CdS/CdTe/Au back contact. Sputtering MZO films with a target containing MgO 11 weight% and ZnO 89 weight% allowed for and increased band gap from 3.3 eV of intrinsic ZnO to 3.65 eV for MZO deposited at room temperature. Increasing the superstrate deposition temperature allowed for a further band gap increase up to 3.95 eV at 400 °C due mainly to an conduction band minimum upward shift. It was highlighted the importance to create a positive conduction band offset with the MZO layer conduction band slightly above the CdS conduction band, with an optimum found in this case to be 0.3 eV (efficiency 10.6 %). By creating a positive conduction band offset all the performance parameters (Voc, FF, Jsc, efficiency) significantly increased. One of the reasons for this improvement was found to be a diminished interface recombination due to a more ideal MZO/CdS band alignment. In the second part of this investigation the MZO was used as a replacement for the CdS in a simplified structure: FTO/MZO/CdTe/Au back contact. The concepts used to optimise the performance of these devices also involved tuning the conduction band alignment between MZO/CdTe and efficiencies of 12.5 % were achieved with a at conduction band offset. The efficiency increase was achieved mainly thanks to a better transparency of the MZO layer and a higher Jsc output, compared to devices using a CdS buffer layer. The MZO buffers have been tested in combination with different TCOs. Results are presented in the third result chapter and showed that AZO is a good alternative to FTO working effectively in combination with MZO. AZO/MZO efficiency thin film CdTe solar cells (12.6%, compared to 12.5% with FTO). It was found that increasing the IR transparency of the TCOs leads to a potentially higher Jsc. Achieving a better transparency was obtained by using TCOs with high mobility and lower carrier concentration (AZO and ITiO) and also by using a boro-aluminosilicate glass with low iron content. ITiO yielded the best opto-electrical properties among all the TCO materials. Devices incorporating ITiO however, showed lower performance then those using FTO and AZO. ITO/MZO windows also yielded poor performance. In addition, the ITO films deposited had a high carrier concentration leading to a high NIR absorption by plasma resonance and resulted not ideal for application in thin film CdTe PV.

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Jurgens-Kowal, Teresa Ann. « Preparation and characterization of synthetic mineral surfaces : adsorption and thermal decomposition of tetraethoxysilane on magnesium oxide, molybdenum, and titanium dioxide surfaces / ». Thesis, Connect to this title online ; UW restricted, 1996. http://hdl.handle.net/1773/9865.

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Pousaneh, Elaheh, Tobias Rüffer, Khaybar Assim, Volodymyr Dzhagan, Julian Noll, Dietrich R. T. Zahn, Lutz Mertens, Michael Mehring, Stefan E. Schulz et Heinrich Lang. « Magnesium β-Ketoiminates as CVD Precursors for MgO Formation ». Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21427.

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The synthesis and characterization of bis(ketoiminato)magnesium(II) complexes of composition [Mg(OCR2CH2CHR1NCH2CH2X)2] (X = NMe2: 3a, R1 = R2 = Me; 3b, R1 = Me, R2 = Ph. X = OMe: 3c, R1 = R2 = Me) are reported. Complexes 3a–c are accessible by the reaction of C(O)R2CH2CHR1N(H)CH2CH2X (X = NMe2: 1a, R1 = R2 = Me; 1b, R1 = Me, R2 = Ph. X = OMe: 1c, R1 = R2 = Me) with MgnBu2. The structure of 3b in the solid state was determined by a single crystal X-ray diffraction study, confirming that the Mg(II) ion is hexa-coordinated by two ketoiminato ligands, while each of the latter coordinates with its two N- and one O-donor atom in an octahedral MgN6O2 coordination environment in the OC-6-33 stereo-isomeric form. The thermal behavior of 3a–c was studied by TG and DSC under an atmosphere of Ar and O2 respectively. The respective Me-substituted complexes 3a,c decompose at lower temperatures (3a, 166 °C; 3c, 233 °C) than the phenyl derivative 3b (243 °C). PXRD studies indicate the formation of MgO. Additionally, TG-MS studies were exemplarily carried out for 3a, indicating the release of the ketoiminato ligands. Vapor pressure measurements were conducted at 80 °C, whereby 3a,c possess with 5.6 mbar (3a) and 2.0 mbar (3c) significantly higher volatilities than 3b (0.07 mbar). Complexes 3a–c were used as MOCVD precursors for the deposition of thin MgO films on silicon substrates. It was found that only with 3a,c thin, dense and rather granulated MgO layers of thicknesses between 28–147 nm were produced. The as-deposited MgO layers were characterized by SEM, EDX, and XPS measurements and the thicknesses of the as-deposited layers were measured by Ellipsometry and SEM cross-section images. Apart from magnesium and oxygen a carbon content between 3–4 mol% was determined.

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Sarpi, Brice. « Etude in-situ de la formation d'oxyde ultra-mince de magnésium sur substrats métalliques et semi-conducteurs ». Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4329/document.

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Ce travail de thèse s’est inscrit dans un cadre fondamental d’étude de la formation contrôlée d’oxydes en couches ultra-minces. Un bâti ultra-vide dédié à la croissance contrôlée de ces oxydes et à leur analyse in-situ (STM-STS, AES et LEED) a été développé. Par une méthode originale de phases alternées de dépôt d’une monocouche atomique de Mg et oxydation à RT, les mécanismes impliqués dans la formation de deux systèmes à fort potentiel applicatif : MgO/Si(100) et MgO/Ag(111) ont été étudiés .Le système MgO/Si(100) a révélé la formation d’une couche ultra-mince de Mg2Si à l’interface entre le MgO et le substrat. En bon accord avec les calculs thermodynamiques réalisés, une cristallisation de cette couche interfaciale dans un processus de dissociation partielle du Mg2Si en MgO à température ambiante a été observée. Identifiée ex-situ par TEM, la relation d’épitaxie associée à cette cristallisation a permis de conclure à la formation d’une hétérostructure MgO / Mg2Si (11-1) / Si(001), témoignant d’une grande qualité d’interface avec le silicium et de la formation d’une couche ultra-mince et amorphe de MgO homogène et isolante (gap de 6 eV).Pour le système MgO/Ag(111), nos résultats expérimentaux couplés aux calculs ab initio de nos partenaires du LAAS ont révélé l’absence de formation d’un alliage de surface ainsi qu’une croissance « liquid-like » du magnésium à RT. Un double empilement O/Mg/O/Mg/Ag(111) suivi d’un recuit UHV à 430°C a ensuite permis la stabilisation d’une couche ultra-mince polaire de MgO(111) qui a été caractérisée par LEED et STM-STS. Les propriétés physico-chimiques et origines possibles de stabilité de cet oxyde polaire ont ensuite été discutées
This PhD work was dedicated to studying the fundamental mechanisms driving the controlled growth of ultra-thin oxide films. An experimental set-up was designed to finely control the growth parameters under UHV conditions while allowing the study of such oxide layers in situ with STM-STS, AES and LEED. Using an original method based on alternate cycles of Mg monolayer adsorption and RT oxidation, we focused on the formation of systems exhibiting a wide range of potential applications: MgO/Si(100) and MgO/Ag(111). The MgO/Si(100) system revealed the growth of an ultra-thin Mg2Si layer at the interface between the MgO and the silicon. In agreement with thermodynamic calculations, a crystallization of this interlayer driven by a partial decomposition of the Mg2Si to a MgO oxide was shown to occur at RT. From ex situ TEM experiments, the involved epitaxial relationship highlighted the formation of an MgO / Mg2Si (11-1) / Si(001) heterostructure. A sharp interface with the silicon was formed, as much as an ultra-thin and amorphous MgO layer exhibiting both a good homogeneity and a high insulating character (bandgap of 6 eV).In the MgO/Ag(111) system, no interfacial alloy formation and a « liquid-like » growth for the Mg were evidenced at RT, using our experimental results coupled with the ab initio calculations performed by our co-workers at LAAS laboratory. Later, a double-layering O/Mg/O/Mg/Ag(111) grown at RT followed by UHV annealing at 430°C resulted in the stabilization of a polar MgO(111) ultra-thin film, which was characterized using LEED and STM-STS. The physicochemical properties of this polar oxide and the potential origin of its stability were discussed

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Bitencourt, José Francisco Sousa. « Produção e caracterização de óxido de alumínio, aluminato de magnésio e filmes finos de óxido de alumínio para aplicações em radioterapia e dosimetria ambiental ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-11072014-014000/.

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Medidas de Termoluminescência (TL), Luminescência Opticamente Estimulada (LOE), EPR (Ressonância Paramagnética de Elétron) e RL (Radioluminescência) foram obtidas de amostras de óxido de alumínio e óxido de alumínio dopado com magnésio. As amostras foram calcinadas em três diferentes temperaturas (1100, 1350 e 1600°C) para observar a variação do comportamento das propriedades luminescentes. Ao final, constatou-se que a temperatura de calcinação é um parâmetro de grande importância para a produção de materiais dosimétricos, pois a amostra com melhores resultados LOE foi o material sem dopante tratada a 1600°C. Em trabalhos anteriores, a composição de óxido de alumínio dopado com magnésio havia apresentado nanoestruturas de aluminato de magnésio, observadas através de Microscopia Eletrônica de Transmissão (MET), que influenciaram a sensibilidade do material à radiação. Amostras de aluminato de magnésio puro e dopado com terras raras foram obtidas na forma de pó e calcinadas a 1100, 1350 e 1600°C. Medidas de TL e LOE de amostras irradiadas com fonte de partículas foram analisadas e comparadas com resultados de EPR e Difração de Raios-X (DRX). Como resultado, foi concluído que, nas condições trabalhadas, somente o elemento gadolínio proporcionou aumento de emissão LOE e TL no espectro visível. DRX indicou a formação dos compostos Al5Er3O12 e Al5Yb3O12; gadolínio e európio também formaram estruturas secundárias que não puderam ser determinadas. A partir do óxido de alumínio em pó, foram produzidos alvos para deposição de filmes finos empregando um sistema de sputtering magnetron e lâminas de silício monocristalino (100) tipo P para substrato. Parâmetros de deposição e de tratamento térmico foram variados de modo a produzir amostras com diferentes características. Curvas de TL foram levantadas e analisadas com relação aos resultados de DRX. Imagens de Microscopia Eletrônica de Varredura (MEV) foram obtidas de algumas amostras para visualizar o estado dos filmes depositados após tratamentos térmicos de 500 e 1100°C. Resultados mostraram a formação de picos de difração de a-Al2O3 em algumas das amostras espessas. Medidas de TL de amostras expostas à radiação ambiente exibiram picos de emissão em posições que variaram de acordo com a composição e espessura do filme depositado.
Thermoluminecent (TL), Optically Stimulated Luminescence (OSL), EPR (Electron spin Resonance) and Radioluminescence (RL) measurements were obtained from aluminum oxide and magnesium doped aluminum oxide samples. The samples were calcinated at three different temperatures (1100, 1350 and 1600°C) in order to observe variation of luminescent properties. As results, it was found that the calcination temperature is of great importance in the production of dosimetric materials, since the undoped sample calcinated at 1600°C showed the highest sensibility. In early works, magnesium doped aluminum oxide samples exhibited the formation of nanostructured layer composed by magnesium aluminate, observed using Transmission Electron Microscopy (TEM), which induced an increase of the luminescent properties. Samples of undoped and rare-earths doped magnesium aluminate, calcinated at 1100, 1350 and 1600°C, were produced. TL and OSL measurements were obtained from irradiated aliquots, analyzed and compared to EPR and XRD results. Results showed that, under the parameters used in this work, only gadolinium doped samples exhibited increase in TL and OSL emissions. XRD indicated the formation of Al5Er3O12 and Al5Yb3O12 structures in doped samples; gadolinium and europium doped samples also showed new structures, which couldnt be identified. Powder aluminum oxide was used to produce deposition targets, which were employed in the deposition of thin films over P type monocrystalline silicon (100) wafers. Variations of deposition parameters and heat treatment induced the formation of thin films with different characteristics, observed by XRD and luminescent analysis (TL). XRD results indicated the occurrence of alpha-Al2O3 in some of the thick films. Samples exposed to natural radiation produced TL emission in the visible spectrum.

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Akyildiz, Hasan. « Hydrogen Storage In Magnesium Based Thin Film ». Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612652/index.pdf.

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ABSTRACT HYDROGEN STORAGE IN MAGNESIUM BASED THIN FILMS Akyildiz, Hasan Ph.D., Department of Metallurgical and Materials Engineering Supervisor : Prof. Dr. Tayfur Ö
ztü
rk Co-Supervisor : Prof. Dr. Macit Ö
zenbas October 2010, 146 pages A study was carried out for the production of Mg-based thin films which can absorb and desorb hydrogen near ambient conditions, with fast kinetics. For this purpose, two deposition units were constructed
one high vacuum (HV) and the other ultra high vacuum (UHV) deposition system. The HV system was based on a pyrex bell jar and had two independent evaporation sources. The unit was used to deposit films of Mg, Mg capped with Pd and Au-Pd as well as Mg-Cu both in co-deposited and multilayered form within a thickness range of 0.4 to 1.5 &mu
m. The films were crystalline with columnar grains having some degree of preferred orientation. In terms of hydrogen storage properties, Mg/Pd system yielded the most favorable results. These films could desorb hydrogen at temperatures not greater than 473 K. The study on crystalline thin films has further shown that there is a narrow temperature window for useful hydrogenation of thin films, the upper limit of which is determined by the intermetallic formation. The UHV deposition system had four independent evaporation sources and incorporated substrate cooling by circulating cooled nitrogen gas through the substrate holder. Thin films of Mg-Cu were produced in this unit via co-evaporation technique to provide concentrations of 5, 10 and 15 at. % Cu. The films were 250-300 nm thick, capped with a thin layer of Pd, i.e. 5-25 nm. The deposition was yielded nanocrystalline or amorphous Mg-Cu thin films depending on the substrate temperature. At 298 K, the films were crystalline, the structure being refined with the increase in Cu content. At 223 K, the films were amorphous, except for Mg:Cu=95:5. The hydrogen sorption of the films was followed by resistance measurements, with the samples heated isochronally, initially under hydrogen and then under vacuum. The resistance data have shown that hydrogen sorption behaviour of thin films was improved by size refinement, and further by amorphization. Among the films deposited, amorphous Mg:Cu=85:15 alloy could absorb hydrogen at room temperature and could desorb it at 223 K (50 º
C), with fast kinetics.

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Guan, Jingcheng. « Modelling zinc oxide thin-film growth ». Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/36311.

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Photovoltaics have a significant role in the solution of energy supply and energy security. Research on photovoltaic devices and their production processes has been carried out for decades. The transparent conducting oxide layer, in the photovoltaic solar cell, composed of aluminium doped zinc oxide, is produced through deposition techniques. By modelling these depositions using classical molecular dynamics, a better understanding on the short term kinetics occurring on the growing surface has been achieved. Compared to the molecular dynamics, the employment of the adaptive kinetic Monte Carlo method enabled such surface growth dynamics simulation to reach much longer time scale. Parallelised transition searching was carried out in an on-the-fly manner without lattice approximation or predefined events table. The simulation techniques allowed deposition conditions to be easily changed, such as deposition energy, deposition rate, substrate temperature, plasma pressure, etc. Therefore, in this project three main deposition techniques were modelled including evaporation (thermal and assisted electron beam), reactive magnetron sputtering and pulsed laser depositions. ZnO as a covalent compound with many uses in semiconductors was investigated in its most energy favourable wurtzite configuration. The O-terminated surface was used as the substrate for the growth simulation. Evaporation deposition at room temperature (300 K) with a stoichiometric distribution of deposition species produced incomplete new layers. Holes were observed existing for long times in each layer. Also, stacking faults were formed during the low-energy (1 eV) growth through evaporation. The reactive sputtering depositions were more capable of getting rid of these holes structures and diminished these stacking faults through high energy bombardments but could also break these desirable crystalline structure during the growth. However, single deposition results with high energies showed that the ZnO lattice presented good capacity of self-healing after energetic impacts. Additionally, such self-healing effects were seen for substrate surface during thin film growth by the sputtering depositions. These facts shed some light on that the sputtering technique is the method of choice for ZnO thin film depositions during industrial production. Simulation results of pulsed laser deposition with separated Zn and O species showed the thin films were grown in porous structures as the O-terminated surface could be severely damaged by Zn atoms during the very short pulse window (10 microseconds). An important growth mechanism with ZnO dimer deposited on the O-terminated polar surface was the coupling of these single ZnO dimers, forming highly mobile strings along the surface and thus quenching its dipole moments, whilst the isolated single ZnO dimers were hardly of this mobility. Such strings were the building blocks for the fabrication occurring on the surface resulting in new layers. Last but not least, a reactive force field for modelling Al doped ZnO was fitted. DFT calculations showed that the Al atoms on the surface were likely to replace Zn atoms in their lattice sites for more energy favourable structures. Al on the ZnO surfaces, structures with Al in the bulk as well as configurations with Al interstitials were used to train the force field to reproduce favourable surface binding sites, cohesive energies and lattice dimensions. The combination scheme of MD and the AKMC allowed simulation work to reach over experimentally realistic time scale. Therefore, crucial mechanisms occurring during the growth could be precisely understood and investigated on an atomistic level. It has been shown from the simulation results that certain types of deposition play significant roles in the quality of resultant thin films and surface morphology, thus providing insight to the optimal deposition conditions for growing complete crystalline ZnO layers.

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Li, Sonny X. « Nitrogen doped zinc oxide thin film ». Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/821916-VLVAK9/native/.

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Thesis (M.S.); Submitted to the University of California, Berkeley, 210 Hearst Mining Memorial Bldg., Berkeley, CA 94720 (US); 15 Dec 2003.
Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--54116" Li, Sonny X. USDOE Director. Office of Science. Basic Energy Sciences (US) 12/15/2003. Report is also available in paper and microfiche from NTIS.

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Özkan, Zayim E., et N. Karamahmutoglu. « Carbon Nanotubes Doped Vanadium Oxide Thin Film ». Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35004.

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Vanadium oxide films were prepared by chemical coating techniques on glass and ITO coated glass substrates. Vanadium oxide films were doped with carbon nanotubes and examined their optical band gap and structures. The effects of carbon nanotubes on visible light absorbance and band gap energies were observed. Electrochemical, structural and optical studies on vanadium oxide coatings were reported in the liquid electrolyte. Optical constant such as refractive index, extinction coefficient, and band gap calculation was done by NKD analyzer. Effect of CNT into vanadium oxide films structural properties were examined by atomic force microscopy (AFM) When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35004

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Meng, Keng-Yuan. « Magnetic Skyrmions in Oxide Thin Film Heterostructures ». The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562856036665345.

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Zhang, Jiawei. « Oxide-semiconductor-based thin-film electronic devices ». Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/oxidesemiconductorbased-thinfilm-electronic-devices(c8cde776-b68b-47b5-ab63-382a86dbb94b).html.

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Oxide semiconductors have been envisaged to find applications in ubiquitous flexible electronics in daily life such as wearable electronic gadgets to offer novel user experiences. However, one of the bottlenecks to realise these applications is a lack of oxide-semiconductor components capable of wireless communications. As Bluetooth and Wi-Fi are the two dominant communication interfaces, fast enough front-end rectifiers must be developed to operate at their gigahertz (GHz) transmission frequencies. Furthermore, despite of significant developments of n-type oxide semiconductors in the last decade, widespread flexible electronics also requires high-performance p-type oxide semiconductors for use in complementary logic circuits. The objectives of this dissertation are to develop high quality Schottky barriers, achieve GHz speed Schottky diodes on rigid and flexible substrates, evaluate the noise properties of the Schottky diodes, develop p-type oxide semiconductor using sputtering technology, elucidate the hole transport mechanism in p type transistors, and demonstrate their potential applications such as radio receivers, complementary inverters and ring oscillators. First, indium gallium zinc oxide (IGZO) Schottky diodes were fabricated by using radio frequency magnetron sputtering. The oxygen content at the metal-IGZO interface was found to have a profound effect on the electrical performance. By introducing 3% O2 during the deposition of Pt or IGZO, the diodes exhibited excellent electrical properties without requiring any annealing treatment, thus allowing for the realisation of flexible IGZO Schottky diodes. The high-frequency properties of Pt-IGZO Schottky diodes on glass substrates were optimised by testing a range of IGZO thicknesses and diode active areas. The achieved highest cut-off frequency was beyond 20 GHz, which is to the best of our knowledge the fastest oxide-semiconductor device to date. On flexible substrates, the diodes also showed cut-off frequencies up to 6.3 GHz, well beyond the critical benchmark speed of 2.45 GHz for typical wireless communications. In order to assess the feasibility of using IGZO Schottky diodes in practical applications, measurements were taken to discern their low-frequency noise properties. In the as-deposited diodes, logarithmic dependence of the noise spectral density on the applied bias was observed, revealing that the dominant noise was generated in the space-charge region at low biases and in the series-resistance region at high biases, respectively. After annealing the diodes, very different noise mechanism was observed and the interface-trap-induced noise dominated the noise spectra. As one of the most promising p-type oxide semiconductors, SnO was also studied at low temperatures in this thesis. The experiment revealed that hole-transport mechanism was governed by either band conduction or variable range hopping in different temperature ranges. Finally, the potential for fully oxide-based electronics was demonstrated by an amplitude-modulation radio receiver comprising of an IGZO Schottky diode as the demodulator and a complementary ring oscillator based on IGZO and SnO transistors. In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of the University of Manchester's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink.

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Lacovig, Paolo. « Electronic structure, morphology and chemical reactivity of nanoclusters and low-dimensional systems : fast photoemission spectroscopy studies ». Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3685.

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2008/2009
L'obiettivo di questa tesi è l'applicazione della spettroscopia di fotoemissione allo studio di nanoparticelle supportate e di sistemi a bassa dimensionalità. Ad una primo periodo dedicato allo sviluppo del rivelatore e del software per un nuovo analizzatore d'energia per elettroni installato presso la linea di luce SuperESCA ad Elettra, è seguita una fase durante la quale ho eseguito una serie di esperimenti mirati ad esplorare le potenzialità del nuovo apparato sperimentale. Il primo risultato ottenuto riguarda la comprensione della relazione che intercorre tra le variazioni della reattività chimica del sistema Pd/Ru(0001) e il numero degli strati di Pd cresciuti in modo pseudomorfico sul substrato di rutenio. La risoluzione temporale raggiunta con la nuova strumentazione ci ha permesso di studiare processi dinamici su una scala temporale fino ad ora inaccessibile per la spettroscopia di fotoemissione dai livelli di core: in particolare abbiamo studiato la crescita del grafene ad alta temperatura sulla superficie (111) dell'iridio e la reattività chimica di nanocluster di Pt supportati su MgO. Nel primo caso abbiamo messo in evidenza come la formazione del grafene proceda attraverso la nucleazione di nano-isole di carbonio che assumono una peculiare forma di cupola. Nel secondo caso siamo riusciti a seguire sia la dinamica del processo di adsorbimento di CO, sia la reazione CO + 1/2 O2 -> CO2 sulle nanoparticelle di Pt depositate su un film ultra-sottile di ossido di magnesio. Infine, abbiamo caratterizzato la morfologia di nanoparticelle di Pd, Pt, Rh e Au cresciute su diversi substrati a base di carbonio, in particolare grafite, nanotubi a parete singola e grafene. Tra i vari risultati abbiamo compreso come l'interazione metallo-substrato dipenda dalla dimensione delle nano-particelle e abbiamo evidenziato il ruolo centrale dei difetti del substrato nei processi di nucleazione e intercalazione.
The objective of this thesis is the application of photoelectron spectroscopy for the investigation of supported nanoclusters and low-dimensional systems. After a first stage devoted to the development of the detector and the software for the electron energy analyser installed on the SuperESCA beamline at Elettra, during the PhD project I've performed a series of experiments aimed to explore the capabilities of the new experimental apparatus. One of the first results concerns the understanding of the relation between the modifications in the chemical reactivity of the Pd/Ru(0001) system and the thickness of the pseudomorphically grown Pd overlayer. The temporal resolution achieved with the new experimental set-up allowed us to study dynamical processes on a new time scale, in particular the graphene growth process at high temperature on the Ir(111) surface and the chemical reactivity of Pt nanoclusters supported on MgO. In the former case, we discovered that graphene formation proceeds via preliminary nucleation of dome-shaped C nano-islands. In the second case, we succeded in following both the dynamics of CO adsorption process and the CO + 1/2 O2 -> CO2 reaction on Pt nanoclusters grown on a ultra-thin film of magnesium oxide. Finally, the morphology of Pd, Pt, Rh and Au nanoclusers grown on different carbon-based substrates (namely graphite, single-walled carbon nanotubes and graphene) has been characterized. Among the results we report the understanding of the dependence of the metal-substrate interaction on the cluster size and the role of defects in the nucleation and intercalation processes.
XXII Ciclo
1972

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16

Han, Sanggil. « Cu2O thin films for p-type metal oxide thin film transistors ». Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/285099.

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The rapid progress of n-type metal oxide thin film transistors (TFTs) has motivated research on p-type metal oxide TFTs in order to realise metal oxide-based CMOS circuits which enable low power consumption large-area electronics. Cuprous oxide (Cu2O) has previously been proposed as a suitable active layer for p-type metal oxide TFTs. The two most significant challenges for achieving good quality Cu2O TFTs are to overcome the low field-effect mobility and an unacceptably high off-state current that are a feature of devices that have been reported to date. This dissertation focuses on improving the carrier mobility, and identifying the main origins of the low field-effect mobility and high off-state current in Cu2O TFTs. This work has three major findings. The first major outcome is a demonstration that vacuum annealing can be used to improve the carrier mobility in Cu2O without phase conversion, such as oxidation (CuO) or oxide reduction (Cu). In order to allow an in-depth discussion on the main origins of the very low carrier mobility in as-deposited films and the mobility enhancement by annealing, a quantitative analysis of the relative dominance of the main conduction mechanisms (i.e. trap-limited and grain-boundary-limited conduction) is performed. This shows that the low carrier mobility of as-deposited Cu2O is due to significant grain-boundary-limited conduction. In contrast, after annealing, grain-boundary-limited conduction becomes insignificant due to a considerable reduction in the energy barrier height at grain boundaries, and therefore trap-limited conduction dominates. A further mobility improvement by an increase in annealing temperature is explained by a reduction in the effect of trap-limited conduction resulting from a decrease in tail state density. The second major outcome of this work is the observation that grain orientation ([111] or [100] direction) of sputter-deposited Cu2O can be varied by control of the incident ion-to-Cu flux ratio. Using this technique, a systematic investigation on the effect of grain orientation on carrier mobility in Cu2O thin films is presented, which shows that the [100] Cu2O grain orientation is more favourable for realising a high carrier mobility. In the third and final outcome of this thesis, the temperature dependence of the drain current as a function of gate voltage along with the C-V characteristics reveals that minority carriers (electrons) cause the high off-state current in Cu2O TFTs. In addition, it is observed that an abrupt lowering of the activation energy and pinning of the Fermi energy occur in the off-state, which is attributed to subgap states at 0.38 eV below the conduction band minimum. These findings provide readers with the understanding of the main origins of the low carrier mobility and high off-state current in Cu2O TFTs, and the future research direction for resolving these problems.

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17

Rossi, Leonardo. « Flexible oxide thin film transistors : fabrication and photoresponse ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14542/.

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Gli ossidi amorfi semiconduttori (AOS) sono nuovi candidati per l’elettronica flessibile e su grandi aree: grazie ai loro legami prevalentemente ionici hanno una mobilità relativamente alta (µ > 10cm^2/Vs) anche nella fase amorfa. Transistor a film sottile (TFT) basati sugli AOS saranno quindi più performanti di tecnologie a base di a-Si e più economici di quelle a base di silicio policristallino. Essendo amorfi, possono essere depositati a basse temperature e su substrati polimerici, caratteristica chiave per l’elettronica flessibile e su grandi aree. Per questa tesi, diversi TFT sono stati fabbricati e caratterizzati nei laboratori del CENIMAT all’Università Nova di Lisbona sotto la supervisione del Prof. P. Barquinha. Questi dispositivi sono composti di contatti in molibdeno, un canale semiconduttivo di ossido di zinco, gallio e indio (IGZO) e un dielettrico composto da 7 strati alternati di SiO2 e SiO2+Ta2O5. Tutti i dispositivi sono stati depositati mediante sputtering su sostrati flessibili (fogli di PEN). Le misure tensione-corrente mostrano che i dispositivi mantengono alte mobilità (decine di 10cm^2/Vs) anche quando fabbricati a temperature inferiori a 200°C. Si è analizzato il funzionamento dei dispositivi come fototransistor rilevando la risposta alla luce ultravioletta e in particolare la loro responsività e spostamento della tensione di soglia in funzione della lunghezza d’onda incidente. Questi risultati consentono di formulare ipotesi sul comportamento dei dispositivi alla scala microscopica. In particolare, indicano che i) la mobilità del canale non è influenzata dall’illuminazione, ii) sia l'IGZO sia il Ta2O5 contribuiscono al processo di fotoconduttività e iii) il processo di fotogenerazione non è adiabatico. La tesi contiene inoltre una descrizione del processo di ricombinazione e presenta un’applicazione pratica di tali dispositivi in un circuito per RFID. Infine, esplora la possibilità di migliorarne la flessibilità e le prestazioni.

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18

Barnes, Jean-Paul L. P. Barnes. « TEM studies of thin film oxide/metal nanocomposites ». Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398136.

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19

Lloyd, Adam L. « Modelling silver thin film growth on zinc oxide ». Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24860.

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Ag thin film growth on ZnO substrates has been investigated theoretically using multi-timescale simulation methods. The models are based on an atomistic approach where the interactions between atoms are treated classically using a mixture of fixed and variable charge potential energy functions. After some preliminary tests it was found that existing fixed charge potential functions were unreliable for surface growth simulations. This resulted in the development of a ReaxFF variable charge potential fitted to Ag/ZnO surface interactions. Ab initio models of simple crystal structures and surface configurations were used for potential fitting and testing. The dynamic interaction of the Ag atoms with the ZnO surface was first investigated using single point depositions, via molecular dynamics, whereby the Ag impacted various points on an irreducible symmetry zone of the ZnO surface at a range of energies. This enabled the determination of the relative numbers of atoms that could penetrate, reflect or bond to the surface as a function of incident energy. The results showed that at an energy of up to 10 eV, most atoms deposited adsorbed on top of the surface layer. The second part of the dynamic interaction involved a multi-timescale technique whereby molecular dynamics (MD) was used in the initial stages followed by an adaptive kinetic Monte Carlo (AKMC) approach to model the diffusion over the surface between impacts. An impact energy of 3 eV was chosen for this investigation. Ag was grown on various ZnO surfaces including perfect polar, O-deficient and surfaces with step edges. Initial growth suggests that Ag prefers to be spread out across a perfect surface until large clusters are forced to form. After further first layer growth, subsequent Ag atoms begin to deposit on the existing Ag clusters and are unlikely to join the first layer. Ag island formation (as mentioned within the literature) can then occur via this growth mechanism. O-deficient regions of ZnO surfaces result in unfavourable Ag adsorption sites and cause cluster formation to occur away from O-vacancies. In contrast, ZnO step edges attract deposited Ag atoms and result in the migration of surface Ag atoms to under-coordinated O atoms in the step edge. Various improvements have been made to the existing methodology in which transitions are determined. A new method for determining defects within a system, by considering the coordination number of atoms, is shown to increase the number of transitions found during single ended search methods such as the relaxation and translation (RAT) algorithm. A super-basin approach based on the mean rate method is also introduced as a method of accelerating a simulation when small energy barriers dominate. This method effectively combines states connected by small energy barriers into a single large basin and calculates the mean time to escape such basin. To accelerate growth simulations further and allow larger systems to be considered, a lattice based adaptive kinetic Monte Carlo (LatAKMC) method is developed. As off-lattice AKMC and MD results suggest Ag resides in highly symmetric adsorption sites and that low energy deposition events lead to no penetrating Ag atoms or surface deformation, the on-lattice based approach is used to grow Ag on larger perfect polar ZnO surfaces. Results from the LatAKMC approach agree with off-lattice AKMC findings and predict Ag island formation. Critical island sizes of Ag on ZnO are also approximated using a mean rate approach. Single Ag atoms are placed above an existing Ag cluster and all transition states are treated as belonging to a single large super-basin . Results indicate that small Ag clusters on the perfect ZnO surface grow in the surface plane until a critical island size of around 500 atoms is reached. Once a critical island size is reached, multiple Ag ad-atoms will deposit on the island before existing Ag atoms join the cluster layer and hence islands will grow upwards. A marked difference is seen for second layer critical island sizes; second layer Ag islands are predicted to be two orders of magnitude smaller (< 7 atoms). This analysis suggests that Ag on ZnO (0001) may exhibit Stranski-Krastanov (layer plus island) growth.

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20

Young, Sheng-Yu. « DLC thin film assisted zinc oxide nanowires growth ». College Park, Md. : University of Maryland, 2008. http://hdl.handle.net/1903/8613.

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Thesis (M.S.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Materials Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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21

Gavanier, Beatrice. « Stability of thin film insertion electrodes ». Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324003.

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22

Benia, Hadj Mohamed. « Spatially resolved optical measurements on supported metal particles and oxide surfaces with the STM ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15862.

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In der vorliegenden Arbeit wurde mit Hilfe eines Photon-STM die Korrelation zwischen optischen Eigenschaften und der lokalen Morphologie an zwei unterschiedlichen Systemen untersucht. Hierfür wurden zum einem oxidgetragene Ensemble von Silber-Partikeln präpariert, wobei sowohl die Partikelform (Kuppel- und Scheibenform) als auch die deponierte Partikeldichte variiert werden konnte. Neben der Präparation solcher Partikel auf Al10O13/NiAl, konnten sphärische Silber-Kolloide geordnet, als auch ungeordnet auf HOPG aufgebracht und untersucht werden. Dabei zeigte sich, dass das Verhältnis von Höhen zu Breiten nicht nur einen signifikanten Einfluss auf die Mie-Resonanz des einzelnen Partikels hat, sondern auch die elektromagnetische Kopplung der Partikel in einem Ensemble stark kontrolliert. Die energetische Lage der Mie-Resonanz zeigt im Fall der kuppelförmigen Ag-Partikel eine starke Abhängigkeit vom Intepartikel-Abstand, was sich in einer Verschiebung zu höheren Energien für eine steigende Partikeldichte äußert. Eine solche Abhängigkeit konnte bei den Ensembles der scheibenförmigen Partikel nicht beobachtet werden. Des weiteren zeigte sich, dass, verglichen mit den ungeordneten Ensembles, die selbstorganisierte langreichweitige Ordnung der Silber-Kolloide auf HOPG nur einen schwachen Einfluss auf die energetische Position der Mie Resonanz hat.Das zweite hier untersuchte System sind dünne MgO Filme unterschiedlicher Dicken auf einem Mo(001) Substrat. Diese zeigen ein reichhaltiges Wachstumsverhalten, welches durch eine Differenz in den Gitterkonstanten von 5.3% begründet ist und erst ab etwa 25 ML zu einem flachen und defektarmen Film führt. Die so induzierte Spannung relaxiert bis zu einer Dicke von etwa 7 ML in einer periodischen Überstruktur die aus abwechselnd flachen und verkippten Ebenen an der MgO-Mo Grenzschicht hervorgeht. Für MgO Filme mit einer Dicke von etwa 12 ML werden dann Schraubenversetzungen, ausgedehnte verkippte Ebenen und Stufenkanten mit einer Orientierung entlang der Richtung beobachtet. Die optische Charakterisierung durch Feldemission von Elektronen aus der STM-Spitze in den MgO-Film wird dominiert von zwei Emissionsmaxima bei Energien von 3.1 eV und 4.4 eV. Die kontrollierte Nukleation von Gold Partikeln und die Erzeugung von Farbzentren im MgO Film erlaubten eine Zuordnung dieser Emissionen zu strahlenden Zerfällen von Exitonen an Ecken, Kinken bzw. Stufen des Magnesiumoxids. Solche Emissionsprozesse konnten allerdings nur unter Einstellungen beobachtet werden, bei denen ein gleichzeitiges Rastern der Oberfläche unmöglich ist. Bei moderaten Einstellungen war auch eine ortsaufgelösten Spektroskopie möglich, wobei dann neue Emissionsmechanismen beobachtet wurden. Dabei sind zwei Prozesse wesentlich; zum einen die Ausbildung von sog. Spitzen-induzierten Plasmonen im Bereich zwischen Spitze und dem Mo-Substrat, zum anderen strahlende Elektronenübergänge zwischen sog. Feldemissionsresonanzen, die sich im Spitze/MgO-Film System ausbilden.
In this thesis, the correlation between the optical properties and the local morphology of supported silver nanoparticle ensembles and MgO thin films deposited on Mo(001) systems is explored by means of Photon-STM. In the first section, dome and disk shaped Ag nanoparticle ensembles with increasing density on an alumina film on NiAl(110) were analyzed as well as ordered and disordered ensembles of Ag nanocolloids on HOPG. The aspect ratio of the Ag nanoparticles was found to have a significant influence not only on the Mie plasmon resonance of a single particle, but also on the electromagnetic coupling within the nanoparticle ensembles. The Mie resonance in the ensemble of dome shaped Ag nanoparticles shows a strong dependence on the interparticle distance, where it shifts to higher energies with increasing particle density, due to destructive interference effects. In the disk-like Ag ensembles, however, the plasmon energy is independent of particle-particle separation. The long-range lateral ordering of size-selected Ag nanocolloids is found to induce a high dipole-dipole coupling within the ensemble. This is mainly reflected by the enhancement of the spectral intensity of the in-plane Mie mode, due to constructive coupling. However, ensembles with either well-ordered or disordered arrangements reveal no important difference in their optical properties, reflecting the weak influence of the long-range order in the particle ensemble. Thin MgO films with different thicknesses were grown on a Mo(001) surface. The stress resulting from the 5.3% lattice mismatch between the MgO(001) and the Mo(001) lattice parameters is found to control the surface morphology of the MgO film until thicknesses of around 25ML at which flat and defect-poor films are obtained. The relaxation of the stress induces a periodic network in the first 7ML of the MgO film, consisting of alternated flat and tilted mosaics. The presence of screw dislocations, steps oriented along the MgO directions, and tilted planes is observed when the MgO films are approximately 12ML thick. In addition, an increase of the MgO work function around these new surface features is revealed from STM spectroscopy. The photon emission induced by field-emitted electron injection from the STM tip into the MgO films is dominated by two emission bands located at 3.1eV and 4.4eV. To check the origin of these bands, further experiments, namely, nucleation of Au particles and creation of F-centers on the MgO surface, have been performed. The nucleation of Au particles at the low coordinated sites is found to quench the MgO optical signal, while the creation or annihilation of F-centers does not alter the MgO emission bands. The 3.1eV and the 4.4eV bands are therefore assigned to the radiative decay of MgO excitons at corner and kink sites, and step sites, respectively. Besides, spatially resolved optical measurements in the tunneling mode of the STM revealed different light emission mechanisms. These radiative processes are mainly related to tip-induced plasmons that form between the tip and the Mo support and to electron transitions between field-emission-resonance states in the STM tip-MgO film junction. The signal from exciton decays at corners and kinks of the MgO surface is however only observed at excitation conditions where the spatial resolution is already strongly reduced.

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23

Beckel, Daniel. « Thin film cathodes for micro solid oxide fuel cells ». kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:29741.

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24

Brown, J. R. « Tin oxide thin film gas sensors deposited by MOCVD ». Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434038.

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25

Lee, S. « Physics and modeling of oxide semiconductor thin film transistors ». Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1400467/.

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In this thesis, we present an intensive investigation on the analytical models to describe the field-effect mobility, the current-voltage (I-V) characteristics, and the instability mechanisms in oxide TFTs, e.g. amorphous In-Ga-Zn-O TFTs. Here, we considered the unique material properties and underlying physics of it, such as the localized tail states, the potential barriers, and the oxygen vacancies. The derived mobility model and the I-V relation for oxide TFTs have been proposed for the first time, yielding a physically-based transistor model for the circuit design and simulation. Also, we developed an analytical method to extract the localized tail state profile to be used as a basis to derive those mobility and I-V models. Here, the relationship between the Fermi-level and gate voltage is derived analytically for the gate voltage-dependent expressions of each model. These models were simulated and compared with the experiments, providing a good agreement with each other. Regarding the instability study, we developed a quantitative analysis on the photoconductive gain due to the oxygen vacancy ionized under illumination, and proposed a gate-pulse spectroscopy to get the ionized oxygen vacancy profile in energy. These studies suggest a visible light sensor application to be embedded into a display panel, e.g. an interactive display, intentionally using the oxygen vacancy-rich layer, e.g. the In-Zn-O, incorporated into a bi-layer channel photo-TFT structure. Consequently, a complete analysis on device physics and modelling of the oxide TFTs is presented in this thesis, providing analytical and quantitative insights into the physics of the oxide TFTs, and their potential for future interactive and transparent electronic systems.

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26

Barquinha, Pedro. « Transparent oxide thin-film transistors : production, characterization and integration ». Doctoral thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/5380.

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Flack, Natasha. « Thin film components for solid oxide fuel Cells (SOFCs) ». Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2007271/.

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Thin film components for solid oxide fuel cells (SOFCs) have been investigated in this thesis. This work focuses on electrolyte materials such as samarium doped ceria (SDC) and cathode materials including neodymium barium cobalt oxide (NBCO) and barium calcium yttrium iron oxide. Single layer growth of NBCO or SDC is achieved on single crystal strontium titanate (001) before these materials were grown via pulsed laser deposition as a bi-layer and multilayers. Ordered NBCO required deposition at 850°C, whereas it was found that the SDC grew with a lower surface roughness at lower temperatures of around 650°C. The motivation was to investigate how the conductivity is affected by the interfaces between these layers, as motivated by previous studies of yttrium stabilised zirconia (YSZ) with strontium titanate (STO). NBCO was found to be unstable at the temperatures required for AC impedance measurements. From the transmission electron microscopy (TEM) and Energy Dispersive X-ray (EDX) data there is likely migration of Nd into the SDC layers. The interfaces are also less sharp for the multilayer films deposited at the higher temperature for the SDC growth. However, in all cases the SDC growth appears more favourable in the TEM when compared to the NBCO, with some regions even showing Co-metal and fluorite structures potentially attributed to Co-Ox where we would expect to see the perovskite block. Thin films of barium calcium yttrium iron oxide were grown on single crystal strontium titanate (001). The material is a candidate cathode for solid oxide fuel cells (SOFCs) and in the intermediate temperature (IT) region at 600°C the in-plane AC conductivity of the thin film is found to be 30.0Scm-1, significantly enhanced over 3.5Scm-1 found for the polycrystalline form. This is assigned to reduction of the grain boundary density and alignment of the planes predicted to have the highest electronic and ionic conductivities. The symmetry of the film appears to be tetragonal within the resolution of the measurements employed, as opposed to the orthorhombic symmetry of the bulk phase, which may be attributed to the in-plane structural match between the cubic STO substrate and the grown layer. Three potential geometries investigating both single and double-sided growth for measuring the area specific resistance of thin films are discussed and an experimental prototype constructed and tested.

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28

Adam, Suhare A. « Thin Film Complex Oxide Proton Conductors : Synthesis and Applications ». Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493335.

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The performance of ultra-thin film solid oxide fuel cells (μ-SOFC) is highly dependent on the structural, microstructural and transport properties of the electrolyte. The focus of this thesis is on understanding the effect of synthesis and processing parameters of BaY0.2Zr0.8O3 (BYZ), a complex oxide proton-conducting electrolyte, on thin-film solid oxide fuel cell (SOFC) performance. The properties of BYZ thin films are highly dependent on film growth techniques and parameters. The relationship between electrolyte thickness and fuel cell performance is investigated in the ultra-thin film thickness range of ~ 70 nm to ~ 200 nm for BYZ films grown by RF sputtering. The microstructure, crystal structure, and electrical behavior of BYZ films were examined as a function of thickness to attain high power density in SOFCs. The optimal thickness that allows for a balance between the leakage current and Ohmic resistance for these devices was determined to be t0 ~150 nm. XRD examination showed a thickness dependent stress behavior in BYZ thin films, with the most compressive state occurring for films of thickness t0. A Volmer-Weber thin film growth mode is proposed for the observed thickness dependent evolution in film properties. The findings of this examination can allow for an increase in the limits of SOFC power density in the ultra-thin regime for proton conducting electrolytes. The presence of a large number of grain boundaries in BYZ films processed at intermediate temperatures leads to diminished conductivity. To mitigate this reduced conductivity while maintaining reasonable processing temperatures, it is essential to increase the effective surface area or TPB of the device. A study of the insertion of ion-selective interfacial layers between the electrode-electrolyte interfaces in μ-SOFCs performance is presented. A nearly two-fold increase in power density of μ-SOFCs in the intermediate temperature range is demonstrated by the addition of ultra-thin palladium interlayers. In addition to enhancing performance, this approach may yield important insight into the proton conduction behavior of BYZ and other proton conducting materials. Finally, to address some of the shortcomings in the current synthesis techniques for BYZ, a novel intermediate temperature thin film synthesis route is demonstrated. This new technique (SP-GNP) is a combination of a thin film deposition technique, Spray Pyrolysis (SP), with a low temperature oxide powder synthesis technique, Glycine Nitrate Process (GNP). A proposed working mechanism and a discussion of the principal parameters that dictate film properties is presented. By using this technique, single-phase perovskite BYZ films were successfully grown at a temperature of 200 °C followed by annealing at 750 °C. The compositional and microstructural evolution of BYZ thin films obtained by SP-GNP is investigated as a function of several technique parameters such as precursor concentration, solvent properties and substrate properties. A microstructural evolution from porous to dense in BYZ thin films by changing precursor composition is demonstrated. This intermediate temperature technique may allow for a deeper insight into the properties of refractory complex oxides through incorporation of novel dopants and may lead to the emergence of new applications for these materials.
Engineering and Applied Sciences - Applied Physics

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Ozgit, Cagla. « Isochronal Hydrogenation Of Textured Magnesium/palladium Thin Films ». Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610385/index.pdf.

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Pure and palladium&
#8208
covered 350 nm thick magnesium thin films were deposited on glass substrates via thermal evaporation. In the as&
#8208
deposited state, films were highly textured with Mg (001) parallel to the substrate. Hydrogen loading experiments were carried out in two different conditions
namely isothermal and isochronal. Hydrogenation behaviors of the thin films were followed by twopoint probe electrical resistance and optical transmittance measurements, as well as x&
#8208
ray diffraction studies. Isothermal hydrogenation experiments conducted on Pd&
#8208
covered Mg thin films have revealed that these films can absorb hydrogen at temperatures starting from 333 K, producing MgH2 with a random texture. When the films were heated slowly starting from the room temperature, on the other hand, hydrogenation gives rise to a textured MgH2, where (110) parallel to the substrate with a minor (101) component. Formation of the textured hydride in isochronal loading was discussed within the context of lattice mismatch in Mg to MgH2 transformation. It was further shown that formation of such a textured hydride in Mg thin films minimizes in&
#8208
plane lattice distortion.

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Pecunia, Vincenzo. « Solution-based polymeric/metal-oxide thin-film transistors and complementary circuits ». Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708401.

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31

REMONDINA, JACOPO. « Ga-rich oxide-in-oxide glass ceramics : from bulk to thin film devices ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/263429.

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In questa tesi presento il lavoro da me svolto durante il mio dottorato su film vetro-ceramici nanostrutturati contenenti ossido di gallio riguardo alla possibile uso di questa classe di materiali in geometria planare all’interno di dispositivi optoelettronici. Negli ultimi tre anni, le mie ricerche sono state rivolte alla comprensione della relazione fra la presenza delle nanostrutture – analizzate attraverso uno studio strutturale dettagliato grazie a diverse tecniche di microscopia e diffrazione in funzione delle condizioni di deposizioni e trattamenti successivi – e i meccanismi fisici di trasporto di carica e polarizzazione che accadono all’interno di film di ossidi-in-ossidi. Il materiale studiato è stato preparato tramite sputtering a radiofrequenze a partire da un precursore vetroso contenente ossidi di Li, Na, Si, Ga e Ge. Come conseguenza del processo di deposizione abbiamo ottenuto un materiale parzialmente cristallino con nanocristalli ricchi in Ga incorporati nel resto della matrice amorfa. Attraverso la microscopia a forza atomica, la riflessione dei raggi x, la diffrazione 2D dei raggi x, la dispersione 2D dei raggi x a piccoli angoli – anche usando luce di sincrotrone – abbiamo completamente caratterizzato i film nanostutturati a diverse scale di grandezza, da pochi nm a qualche micron. L’analisi dettagliata dei risultati mostra la formazione di molteplici nanocristalli anisotropi di spinello di ossido di gallio con dimensioni di 3 nm, che formano aggregati lenticolari di dimensioni maggiori con differenze significative nelle dimensioni nel piano e fuori dal piano. Come risultato dell’indagine di campioni trattati differentemente, lo studio ha inoltre mostrato che la distribuzione e la morfologia di nanostrutture può essere controllata dalle condizioni della deposizione, dalla durata e dalla temperatura del trattamento termico seguente. Partendo dalla conoscenza delle caratteristiche strutturali, l’attività di ricerca è stata indirizzata verso l’approfondita comprensione delle proprietà di trasporto di carica risultanti dalla natura nanostrutturata del materiale, inclusa la nanofase in Ga2O3 semiconduttore e la matrice ospite dielettrica. La risposta elettrica – analizzata con l’aiuto della spettroscopia di impedenza complessa – si è rivelata essere la risultante di molteplici meccanismi di trasporto e di carica dovuti a matrice e nanofase, incluse le interfacce interne. I dati suggeriscono che il trasporto di carica è supportato da una combinazione di meccanismi attivati termicamente per hopping e per effetto tunnel mediati da un percorso di percolazione costruito dalle caratteristiche nanostrutturali del materiale. Curiosamente, la risposta nel suo complesso ha fornito indizi preliminari di plasticità elettrica, rendendo i film sottili nano-vetroceramici dei promettenti candidati come sistemi chiave in dispositivi avanzati per memorie completamente inorganiche ossido-in-ossido ispirate al cervello umano.
In this thesis I present the work I have carried out during my PhD on Ga-oxide containing nanostructured glass-ceramic films as a potential breakthrough for the implementation of this class of material in planar geometry for applications in the field of optoelectronics. In the last three years, my investigations have been aimed at understanding the relationship between the occurrence of nanostructuring – analysed through a detailed structural studies by means of different microscopy and diffractometric techniques as a function of deposition conditions and post-deposition treatments – and the physical mechanisms of charge transport and polarization taking place in oxide-in-oxide films. The studied material was produced by RF sputtering deposition starting from a glass target of Li, Na, Si, Ga and Ge mixed oxide. As a consequence of the deposition process we have obtained partially crystallized material with Ga-rich nanocrystals incorporated in the remaining amorphous matrix. Through atomic force microscopy, x-ray reflectivity, 2D-x-ray diffraction, 2D-small angle x-ray scattering - also employing synchrotron radiation facilities - we have fully characterized the nanostructured films at different length scales, from few nm to few microns. The detailed analysis of the results shows the formation of multiple anisotropic spinel Ga-oxide nanocrystals with size of about 3 nm, forming larger lenticular aggregates with significant differences between the in-plane and the out-of-plane dimensions. As a result of the investigation of differently treated samples, the study also shows that size distribution and morphology of the nanostructures can be controlled by deposition conditions, duration and temperature of post-deposition thermal treatments. Starting from the knowledge of the structural features, the research activity has been directed to the deep understanding of the charge transport properties resulting from the nanostructured nature of the material, including the Ga2O3 semiconductor nanophase and the dielectric host matrix. The electrical response – analysed with the aid of complex impedance spectroscopy – turns out to be the results of multiple contributions to transport and charging mechanisms by the matrix and the nanophase, including the effects of the internal interfaces. The data suggest that the charge transport is sustained by a combination of thermally activated hopping and tunnelling mechanisms mediated by the percolation path built up by the nanostructured features of the material. Interestingly, the overall response gives preliminary evidences of electrical plasticity, making nano-glassceramic thin films potential candidates as key systems in advanced devices for brain-inspired oxide-in-oxide fully inorganic memories.

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32

Hu, Xiao. « Ultra-thin oxide films ». Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:d7373376-84f1-459e-bffb-f16ce43f02b7.

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Oxide ultra-thin film surfaces have properties and structures that are significantly different from the terminations of the corresponding bulk crystals. For example, surface structures of epitaxial ultra-thin oxide films are highly influenced by the crystallinity and electronegativity of the metal substrates they grown on. Some enhanced properties of the novel reconstructions are related to catalysis, sensing and microelectronics, which has resulted in an increasing interest in this field. Ultra-thin TiO_x films were grown on Au(111) substrates in this work. Two well-ordered structures within monolayer coverage - honeycomb (HC) and pinwheel - were generated and investigated. Special attention has been paid to the uniform (2 x 2) Ti₂O₃ HC phase including its regular structure and imperfections such as domain boundaries (DBs) and point defects. Linear DBs with long-range repeating units have been observed; density functional theory (DFT) modelling has been used to simulate their atomic structures and calculate their formation energies. Rotational DBs/defects show up less frequently, however a six-fold symmetrical 'snowflake' DB loop stands out. Two types of point defects have been discovered and assigned to Ti vacancies and oxygen vacancies/hydroxyl groups. Their diffusion manners and pairing habits have been discussed within an experimental context. The results of growing NbO_x ultra-thin films on Au(111) are also presented in this thesis. An identical looking (2 x 2) HC structure to the Ti₂O₃ ultra-thin film has been formed; a stoichiometry of Nb2O3 is suggested. Another interesting reconstruction is a hollow triangle structure. Various sizes have been found, and sides of these equilateral triangles all show a double-line feature aligned along the { 1 ₁⁻ } directions of the Au(111) lattice. Chemical composition characterisations of NbO_x thin films are still required as is DFT modelling. Experimental techniques used in this thesis include scanning tunnelling microscopy (STM), low energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS). Ultra-thin oxide films were created by physical vapour deposition (PVD) in ultra-high vacuum (UHV) systems.

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Vempati, Sesha Pavan Kumar. « Thin film and nanostructures zinc oxide : characterisation and device applications ». Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580108.

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This thesis reports the preparation and characterization of ZnO films and nanostructures and their incorporation in simple devices. The characterization includes imaging techniques - atomic force-, scanning electron- and transmission electron- microscopies (and accompanying analysis) - as well as X-ray diffraction (confirming wurzite structure in all the form of ZnO), photoluminescence (elucidating exciton and defect bands), Raman spectroscopy (dopent incorporation, including defects) and, importantly, optical absorption since it is crucial to confirm the various forms of ZnO as transparent conducting oxide. Also, electron scanning tunnelling microscopy reveals interesting bias- and polarity-dependent changes in 'topography' images originating with different density-of-states contributions from the conduction band, valence band and defect (surface) states. A new fabrication methodology, based on metal-salt decomposition, is introduced to prepare un doped and Co-doped thin films and nanowires on quartz where the doped ZnO exhibited Co2+ substitution of Zn2+ while retaining good optical transmission. Extending the wet-chemical approach synthesis a simple change in reaction temperature led to two quite different forms of ZnO-nanostructure:- nanocrystals and nanosheets. The potential of ZnO-nanosheets as a phosphor coating for producing (bluish-) white light from UV-LEDs is demonstrated. The nanocrystals were used in poly(3, 4- ethylenedioxythiophene)-poly(styrenesulfonate)(pEDOT:PSS) host matrix to form a nanocomposite exhibiting the fascinating property of negative photoconduction, explained in terms of decreased conductivity of the ZnO stemming from a charge transfer interaction with the PEDOT:PSS. The well-known difficulty in forming stable p-type 2nO films was confirmed by fabricating Li-doped 2nO/n-type 2nO homojunctions which failed to show rectifying behaviour, where the oxygen vacancies may indicate extinction of p-type behavior. However, a number of successful n-2nO (Ga- and In-doped 2nO films, honeycomb structured intrinsic .n-2nOIPEDOT:PSS and Ag-doped 2nO nanorods/p-Si heterojunctions were fabricated and their photoresponse examined in detail - these data, in particular polarity-dependent wavelength selectivity, are discussed and analysed in terms of basic band structure and carrier transport properties.

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34

Golden, Stephen John. « Behaviour of thin film oxide based electrodes in electrochromic applications ». Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47080.

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35

Simrick, Neil Jonathan. « Patterned thin film cathodes for micro-solid oxide fuel cells ». Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/11910.

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Williams, Lizandra Clarissa. « Cathodoluminescence and degradation of oxide thin film and powder phosphors ». [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008391.

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37

Chiu, Chien-Ta, et 邱健達. « Study of Magnesium Oxide as Insulating Dielectric Thin Film by RF Magnetron Sputter ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/82607028834686025214.

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碩士
龍華科技大學
電子工程系碩士班
104
MgO thin films were deposited using MgO ceramic target by RF magnetron sputter. The effects of both deposition pressure and annealing temperature on MgO dielectric property have been evaluated. MgO films were deposited pressure at 2 pa, 4 pa, 13 pa and 15 pa and annealed at 350 ℃, 450 ℃, 550 ℃, 650 ℃and 750 ℃ for 120 minutes. The results clearly show that the MgO film deposited at 13 pa and subsequently annealed at 450 ℃ exhibits the largest dielectric constant, which is 36 for 1KHz, respectively. Moreover, leakage current will increase as annealing temperature increasing. With 13 pa pressuring, the leakage current of BST films annealed at 450 ℃, 550 ℃, 650 and 700 ℃ is 2.1×10-7, 1.14×10-4, 4.4×10-5A/cm2 and 4.6×10-4 A/cm2, respectively.

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38

Hung-HsuLin et 林泓旭. « Investigation of magnesium zinc oxide thin film transistors fabricated by sputtered system and their optoelectronic application ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/99837492176738674372.

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miao, zheng-you, et 繆政佑. « The study of resistive switching properties and mechanisms of magnesium oxide thin films ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/8w3r6e.

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碩士
國立高雄大學
應用物理學系碩士班
103
Recently, resistance random access memory (RRAM) have attracted much attention, magnesium oxide (MgO) thin films is one of the most important research. In this work, the MgO films were deposited on silicon substrates by using magnetron sputtering on a MgO target at room temperature. In the process, we used different work atmosphere (Ar,Ar+O2,Ar+N2). A thermal annealing was performed at 800℃ for 1 hour in nitrogen ambient. After experiment, we analyzed the physical characteristic, resistive switching properties and the conduction mechanisms. According to experimental results indicate that the resistive switching properties of MgO films deposited by adding nitrogen ambient is better than oxygen ambient. Besides, the MgO film structure (metal-insulator-semiconductor-MIS) displays bipolar resistance switching properties and also indicate that the conduction mechanisms in MgO films is dominated by the space-charge limited conduction and Ohmic conduction in high resistance state (HRS) and low resistance state (LRS), respectively. At least, we proposed here that the resistance change is due to the migration of oxygen vacancy (VOs).

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40

Cheng-WeiLin et 林承緯. « Optoelectronic Properties on Indium-Magnesium-Oxide (MIO) Thin Film Transistors and Improvement by Using Cap Layer and Buffer Layer ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/56068341043983267045.

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碩士
國立成功大學
微電子工程研究所
104
In this thesis, we utilize co-sputter system to prepare amorphous indium magnesium oxide (MIO) thin film; moreover, thin film transistors (TFTs) and UV phototransistors are fabricated and analyzed. First, we deposit a-MIO thin film on the glass substrate and investigate the properties of thin film with adjusting the power of the target. The result of materials analysis show amorphous structure and smooth surface. And then we demonstrate MSM UV photodetectors. It is found that the cutoff wavelength of the phototransistors can shift by changing the RF sputter power of the In2O3 target. With 3 V applied bias, it is found that measured cutoff wavelength are 315 nm, 330 nm, 340 nm, respectively. We have same results compared with the transmission spectrum analysis. In the second part of the experiment, the fabrication of thin film transistors and UV phototransistors are demonstrated by changing the power of targets. In our experiment, we totally realize nine different parameters of thin film transistors. The optimized device, sample E, exhibits the great properties with a μFE of 8.45 cm2/Vs, a SS of 0.43 V/decade, and an on/off current ratio of 4.1×106. And then we apply a-MIO thin film to the thin film transistors, it is found that the performance of the phototransistors are strongly dependent on the In2O3. The cutoff wavelength of the phototransistors is red-shift from 315 nm to 340 nm. The photo-responsivity and DUV-to-visible rejection ratio of the fabricated are 0.39 A/W and 3.1×103. At last, to further enhance the various electrical properties of thin film transistors, so we use two ways to improve. First, because the cuprous oxide is p-type semiconductor then we deposit it on the thin film transistors to be the cap layer. In this design, it is found that thin film transistors is enhanced for electrical properties and stability and it exhibits μFE of 29.8 cm2/Vs, a SS of 0.22 V/decade, and an on/off current ratio of 1.2×106. Compared with the sample E, it is found that we can achieve higher electrical properties. Second, the fabricated of a-MIO thin film transistors is inserted respectively two different buffer layer are demonstrated, and the thin film transistors with Al2O3 buffer layer has better electrical properties. The result can be contributed to the processing method of the buffer layer affects interface quality. As mentioned above two improvement methods, we know that it can enhance thin film transistors properties efficiently.

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41

Lu, Ting-yi, et 呂婷以. « Preparation of Silicon Oxide Thin Film on AZ91D Magnesium Alloys by Atmospheric Pressure Plasma Jet and its anti-corrosion behavior ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/82283479123816164313.

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碩士
國立臺灣科技大學
機械工程系
102
Magnesium alloys are used in many industries because of their excellent mechanical properties. Their high strength/weight ratio and excellent machinability make magnesium alloys ideal construction materials. In addition, the high recyclability of magnesium makes it very cost-effective for use in industrial manufacturing. However, poor corrosion resistance restricts the applications of magnesium and its alloys in marine environments and in biological applications. The ability to increase the corrosion resistance of magnesium and its alloys is crucial to increase the range of applications. This research aims to overcome this drawback by increasing corrosion resistance. We deposited silicon oxide (SiOx) thin film as an anticorrosion layer using atmospheric pressure plasma jet (APPJ) on AZ91D magnesium alloys. This process combines the benefits of the APPJ process and SiOx thin film. With a high deposition rate and clean dry process, the APPJ process is an excellent candidate for surface coating treatment. The results show that after ageing the SiOx thin films for at least 56 days, the SFE(surface free energy) of deposited SiOx thin films was lower compared to AZ91D alloy, and this resulted in a more hydrophobic surface, which helped to prevent corrosion. The surface morphologies of SiOx thin films were uniformly smooth and consisted of nano-scale silicon oxide particles, which agglomerated more closely with increasing O2 carrier gas flow rate. According to the results of ESCA and AES, the thin films were demonstrated to be carbon-free inorganic SiOx thin films and the O/Si ratio was extremely close to 2.0. From the AES depth profile, the thickness of the SiOx thin films ranged from 45 to 99 nm. The thickness was not directly proportional to the O2 carrier gas flow rate and this was attributed to the lack of energy such that the dissociation of the precursor monomer was inadequate, i.e. in the power deficient regime. The functional groups identified from FT-IR revealed that the degree of porosity of SiOx thin films depended on the cage structure, and this affected the corrosion resistance of SiOx thin films. The carrier gas flow rate evidently affected the quality of SiOX thin films in the APPJ process: 1. monomer deficient regime at lower carrier gas flow rate resulted in a hydrophilic surface; 2. power deficient regime at higher carrier gas flow rate resulted in a lower deposition rate. After corrosion measurement by potentiodynamic polarization tests in 3.5 wt% NaCl solution, the deposited SiOx thin film (O1800) revealed superior corrosion resistance in terms of corrosion potential (Ecorr= -1.28 V(Ag/AgCl)) and corrosion current (Icorr = 1.24 μA/cm2) compared to the AZ91D alloy (Ecorr= -1.46 V(Ag/AgCl), Icorr = 22.06 μA/cm2).

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42

Pousaneh, Elaheh. « Synthesis and Characterization of Metal Complexes for Thin Film Formation via Spin-Coating or Chemical Vapor Deposition ». 2019. https://monarch.qucosa.de/id/qucosa%3A72463.

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The present thesis describes the synthesis and characterization of magnesium, copper, and iron complexes and their application in the MOCVD (Metal-Organic Chemical Vapor Deposition) process, as well as the synthesis and characterization of yttrium and gadolinium complexes and their use as spin-coating precursors for metal oxide thin layer formation. The objective of this scientific work is the development of the family of bis(β-ketoiminato) magnesium(II) complexes and a series of heteroleptic β-ketoiminato copper(II) precursors for the formation of magnesium oxide and copper/copper oxide layers by using the MOCVD process. Modifications of the ketoiminato ligands affect the physical and chemical properties of the respective complexes. Another central theme of this work is the development of β-diketonato iron(III) complexes for the deposition of carbon-free gamma- and alpha-Fe2O3 layers via MOCVD. The thermal behavior and vapor pressure of the precursors could be influenced by the variation of the β-diketonate ligands. In addition, the synthesis and characterization of yttrium and gadolinium β-diketonates and their use as spin-coating precursors are described. Field-effect transistors were successfully fabricated by the deposition of carbon nanotubes on top of the Y2O3 films.

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43

Yekehtaz, Mehdi. « Evaluation of Porosity and Corrosion Protection Ability of Sol-Gel Deposited Oxide Thin Films on Magnesium ». Phd thesis, 2010. https://tuprints.ulb.tu-darmstadt.de/2312/1/Mehdi_Yekehtaz.pdf.

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Some valuable properties of magnesium like high strength-to-weight ratio, high thermal conductivity, good electromagnetic shielding and machinability have made it an excellent material for various applications in automobile and aerospace components, sporting goods and household equipments. Despite of these valuable properties, poor corrosion and wear resistance restrict its application. The deposition of a protective film acting as a barrier between the material and its environment is an effective solution to preserve the metal from a corrosive attack. Good adhesion, uniformity and freedom from defects are necessary properties to ensure a good protection performance. Sol–gel deposition can provide ceramic-like films with high density and hardness at very low temperatures in a fast and inexpensive way. The low reaction temperature and the mixture of organic and inorganic materials lead to the formation of coatings containing both inorganic and organic moieties. The inorganic component enhances hardness, durability and adhesion to the metal substrate while the organic component leads to an increased flexibility and density. The major challenge of sol–gel deposited films is the prevention of pinholes and open porosities arising from the deposition process. Local porosities can produce direct paths between the corrosive environment and the substrate and increase the susceptibility of the materials to corrode. Despite of huge effort on resolving of this drawback, there is still no systematical manner to overcome this problem. In this work, several thin films obtained from sol-gel solutions containing silicon and zirconium were deposited on magnesium samples. Effect of sol solution parameters such as the amount of catalyst, stabilizing agent, water, co-solvent and heat treatment temperature on the porosity of the final film was investigated. Electrochemical methods such as potentiodynamic scans and electrochemical impedance spectroscopy were applied. It was shown that along with other parameters, the structure of precursor also plays an important role on the porous nature of the resulting film. It was also shown that these films are able to increase the corrosion resistance of magnesium in several environments. Film characterization methods proved the formation of an inter-diffusion layer between substrate and the coating which could be responsible for corrosion resistance enhancement.

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Lo, Yu Hsin, et 羅煜欣. « Preparation and Applications of RF-Sputtered Transparent Conductive Thin Films of Aluminum-doped Magnesium Zinc Oxide ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/95050505582488352997.

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碩士
長庚大學
化工與材料工程學系
99
The objectives of this research are to preare the ceramic targets of aluminum-doped magnesium zinc oxid (AMZO) by solid-state reactions and the thin films of AMZO by RF magnetron sputtering. In addition, the effects of the amount of alumina and magnesium dopant in the AMZO targets as well as other sputtering parameters on the electrical, optical, and structural properties of AMZO thin films was also investigated. Finally, AMZO thin film would be applied for CIGS solar cell. In the result, the Zn0.94Mg0.06O with 1 wt% Al2O3 at different sintering temperature exhibit the same hexagonal wurtzite ZnO structure. The lowest resistivity of 6.2×10-3 Ω-cm was abtained for the sintering of AMZO target at temperature of 1400℃ and less than 5% weight loss. It was also found that the AMZO ceramic targets with different Al2O3 or Mg contents at sintering temperature of 1400℃ excludes the possibility of ant extra phases. In conclusion, the resistivity and the relative density of the target by AMZO target were 2.6 x 10-3 Ω-cm and 98.46%, respectively. The best performance of the electricity could achieve under the hybrid amount of Al2O3 and the sintered temperature were 3 wt% and 1400 ℃, respectively. Following the application by the AMZO target, the thin films were prepared by RF sputtering system and subtract temperature, power and working pressure were be discussed of the thin film were studied. Compared to the performance of AMZO thin film, the resistivity, mobility concentration, mobility, average transmittance (400 -1200 nm ) and band gap were 1.7 x 10-3 Ω-cm, 3.25 x 1020 cm-3, 11.3 cm2/Vs, 93.1% and 3.68 eV, respectively, under the subtract temperature, power, working pressure and deposited minutes were 320℃, 80 W, 9 mtorr and 15 min, respectively. By implying the AMZO target with different amounts of Al2O3 wt%, compared to the electricity and the optic properties of the AMZO thin film, the best resistivity, mobility concentration, mobility, average transmittance ( 400 -1200 nm ) and band gap were 7.61 x 10-4 Ω-cm, 5.01 x 1020 cm-3, 16.4 cm2/Vs, 91.5% and 3.7 eV, respectively, by the AMZO target with 2 wt% Al2O3：Zn0.98Mg0.02O.

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45

Jou, Jia Chiuan, et 周家全. « Preparation and Applications of RF-Sputtered Transparent Conductive Thin Films of Gallium-doped Magnesium Zinc Oxide ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/63310618514172458451.

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碩士
長庚大學
化工與材料工程學系
100
The preparation of transparent conductive gallium-doped magnesium zinc oxide (GMZO) thin films with good near infrared transmission by radio frequency (RF) magnetron sputtering using a single GMZO ceramic target was explored In addition, the different of GMZO target conditions on the structural, electrical and optical properties on the RF-sputtered GMZO thin films was also investigated and sputtering processes prepared optimization GMZO transparent conductive film application in the CIGS solar cells. Then, the window on the component layer (buffer layer / intrinsic layer / transparent conductive layer) was optimized to increase the optical transmittance by the optical simulation software, increasing the efficiency of photoelectric conversion in the CIGS solar cells. This study results show that the ceramic target in GMZO, that in the amount of 3 wt% Ga2O3 and amount of 2 at% Mg doped with hexagonal wurtzite ZnO structure, the lowest resistivity of 1.2×10-3 Ω cm and the weight loss is less than 5% conditions was held at sintering conditions of a positive argon pressure of 50 kPa and the sintering temperature of 1400 ° C The preparation of the GMZO transparent thin film by RF magnetron sputtering method use to the above-mentioned preparation GMZO ceramic target, that was investigated the structure, electrical and optical properties. The sputtering process conditions on GMZO transparent conductive film structure has not changed much, their preferred orientations are (002) direction, and all belong to the ZnO wurtzite structure. Transparent conductive GMZO thin films with resistivity as low as 2.89 x10-4 Ω cm with a higher carrier concentration of 11.8 x1021 cm-3 and electron mobility of 18.2 cm2/ Vs, good near infrared transmittance (>89%) and bandgap value of about 3.73 eV were successfully prepared on glass substrates by single cathode RF magnetron sputtering using a GMZO ceramic target with the composition of 95 % Zn0.98Mg0.02O and 5 wt% Ga2O3 without post deposition annealing. The preparation of the window layer antireflection coating design and application to CIGS solar cell by using optical simulation software (Film Star) was explored. Finally, Anti-reflective coating was optimized and applied in window layer of CIGS solar cell. Experimental results show that the window layer penetration to enhance short-circuit current and the photoelectric conversion efficiency of CIGS solar photoelectric conversion element of the phenomenon of both increased. The maximum conversion efficiency was 8.22%,and short-circuit current increased 38 percent.

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46

Yekehtaz, Mehdi [Verfasser]. « Evaluation of porosity and corrosion protection ability of sol-gel deposited oxide thin films on magnesium / eingereicht von Mehdi Yekehtaz ». 2010. http://d-nb.info/1008094854/34.

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47

Chen, Chih Hsiu, et 陳芝岫. « Preparation of RF-Sputtered Magnesium Zinc Oxide Thin Films and Their Applications as Buffer Layers in Cu(In,Ga)Se2 Solar Cells ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/25925693303105479719.

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碩士
長庚大學
化工與材料工程學系
101
Magnesium zinc oxide (MgxZn1-xO ) thin films were prepared by RF- magnetron sputtering and attempted to used as buffer layer and intrinsic layer in Cu(In,Ga)Se2 solar cells. The effects of substrate temperature, sputtering power, working pressure, and oxygen flow rate on the structural, electrical and optical properties of Mg0.02Zn0.98O thin films were also investigated. Mg0.02Zn0.98O thin films with resistivity as low as 2.96 ×103 Ω-cm were obtained at the deposition condition of substrate temperature 150 ℃, sputtering power 40 W, working pressure 3 mtorr, pure Ar atmosphere with Ar flow arte being 10 sccm. By increasing the oxygen flow rate in the working gas, the resistivity of Mg0.02Zn0.98O thin films was found to increase. By using Mg0.02Zn0.98O thin films deposited without substrate being heated to replace CdS as buffer layer (CIGS/Mg0.02Zn0.98O/i-ZnO/GMZO) or ZnO as intrinsic layer (CIGS/CdS/Mg0.02Zn0.98O/GMZO), the photovoltaic conversion efficiencies of the CIGS solar cells were, respectively, 1.618% and 1.693%, which were better than that of the CIGS solar cells (1.363%) with the structure of CIGS/Mg0.02Zn0.98O/GMZO. However, by replacing Mg0.02Zn0.98O with Mg0.05Zn0.95O, the photovoltaic conversion efficiency of the CIGS solar cells with the structure of CIGS/Mg0.05Zn0.95O/GMZO improved to 3.513%.

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48

YANG, FU-HAI, et 楊福海. « Studies on the Photoelectric Properties of Magnesium Tin Oxides Thin Films ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4zue43.

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碩士
國立虎尾科技大學
材料科學與工程系材料科學與綠色能源工程碩士班
106
In this study, MgO/SnO2 films were synthesized by the sol–gel and spin coating. The effects of electrolyte, various dopant species and contents, coating layers, and sintering temperatures on the structure, microstructure and photoelectric properties were investigated. The MgO/SnO2 composite films were formed after annealing at 400-600oC. It was observed that proper electrolyte concentration and sintering condition could improve the degradation efficiency of azo dyes AO7 and photoelectric conversion efficiency. After annealing at 800oC, the films began to form Mg2SnO4 structure. On annealing at 1200oC, Mg2SnO4 is the main crystalline phase with small trace of SnO2. Under UV excitation, Mn- and Ti-doped phosphor showed emission bands centering at 500 nm (green) and 440 nm (blue), respectively. Different concentrations of activators and coating layers affected the surface morphology and luminescence of films.

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Jeong, Yongwoo. « Zinc oxide thin film transistors ». 2007. http://proquest.umi.com/pqdweb?did=1320961681&sid=10&Fmt=2&clientId=39334&RQT=309&VName=PQD.

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Thesis (M.S.)--State University of New York at Buffalo, 2007.
Title from PDF title page (viewed on Nov. 13, 2007) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Anderson, Wayne A. Includes bibliographical references.

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Cho, Sungmee. « Nanostructured Thin Film Electrolyte for Thin Film Solid Oxide Fuel Cells ». Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10145.

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Solid oxide fuel cells (SOFCs) are very attractive as energy generation devices because they are clean, reliable, and almost entirely pollution-free. SOFCs have flexible fuel selections compared with other fuel cell technologies. The main disadvantage of SOFCs is their high operating temperature (~1000ºC for conventional SOFCs) which leads to cell cracking and formation of non-conducting compounds at electrolyte/electrode interfaces. Therefore, intermediate temperature SOFCs (ITSOFCs) in the range of 500-700 ºC has attracted extensive research interests. To achieve high cell performance at reduced temperatures, it requires high-catalytic activity, high ionic conductivity, and comparable thermal expansion coefficient (TEC) of the cell components. To address the above issues, the research focuses on two main approaches (i.e., the interlayer approach and the electrolyte approach) in order to improve the overall cell performance. First, the design of a thin layer of a vertically-aligned nanocomposite (VAN) structure as an interlayer between the electrolyte and cathode is demonstrated. The development of the VAN structures consisted of the cathode material as a perovskite or ordered double perovskite structure, La0.5Sr0.5CoO3 (LSCO) or PrBaCo2O5 delta (PBCO), and the electrolyte material as a fluorite structure, Ce0.9Gd0.1O1.95 (CGO or GDC), were achieved for thin film solid oxide fuel cell (TFSOFCs). The VAN structure significantly improves the overall performance of the TFSOFC by increasing the interfacial area between the electrolyte and cathode and also acts as a transition layer that improves adhesion and relieves both thermal stress and lattice strain. Second, microstructural and electrical properties of Gd-doped CeO2 (GDC, Ce0.9Gd0.1O1.95) thin films electrolyte are studied for intermediate temperature solid oxide fuel cells (SOFCs). The GDC thin film electrolytes with different grain sizes and grain morphologies were prepared by varying the deposition parameters such as substrate temperature, oxygen partial pressure, target repetition rate, and laser ablation energy. The electrical property of the GDC thin film is strongly affected by the grain size. Third, bilayer electrolytes composed of a gadolinium-doped CeO2 (GDC) layer (~6 micrometer thickness) and an yttria-stabilized ZrO2 (YSZ) layer with various thicknesses (~330 nm, ~440 nm, and ~1 micrometer) are achieved by a pulsed laser deposition (PLD) technique for thin film solid oxide fuel cells (TFSOFCs). One effective approach is to incorporate YSZ thin film as a blocking layer in between the GDC and anode for preventing chemical reduction of GDC and electrical current leakage. This bilayer approach effectively improves the GDC's chemical/ mechanical stability and reduces the OCV loss under reducing conditions. The results suggest that the YSZ thin film serves as a blocking layer for preventing electrical current leakage in the GDC layer and also provides chemical, mechanical, and structural integrity in the cell, which leads to the overall enhanced performance.

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