Dissertations / Theses on the topic 'Thickness dependences'
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Bharadwaj, Shashank. "Investigation of oxide thickness dependence of Fowler-Nordheim parameter B." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000251.
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Johnsson, Peter. "Processing and Properties of Ultrathin Perovskite Manganites." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3511.
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Lin, Weiwei, Kai Chen, Shufeng Zhang, and C. L. Chien. "Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator." AMER PHYSICAL SOC, 2016. http://hdl.handle.net/10150/614754.
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We report a large enhancement of thermally injected spin current in normal metal (NM)/antiferromagnet (AF)/yttrium iron garnet (YIG), where a thin AF insulating layer of NiO or CoO can enhance the spin current from YIG to a NM by up to a factor of 10. The spin current enhancement in NM/AF/YIG, with a pronounced maximum near the Neel temperature of the thin AF layer, has been found to scale linearly with the spin-mixing conductance at the NM/YIG interface for NM = 3d, 4d, and 5d metals. Calculations of spin current enhancement and spin mixing conductance are qualitatively consistent with the experimental results.
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Tamai, Goro. "Experimental study of engine oil film thickness dependence on liner location, oil properties and operating conditions." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/31066.
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Chen, Cheng. "Anchoring Transitions of Liquid Crystals on Large Angle Deposited SiOx Thin Films." Kent State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=kent1164139845.
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Galgauskas, Saulius. "The determination of the central corneal thickness of the Lithuanian population and its dependence on age, gender and body constitution." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20111102_111028-08585.
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Cornea is a part of the optical system of the eye, the condition of which is directly related with the eyesight and its quality. Due to the increasing popularity of the correction of refraction defects with the help of excimer laser, central cornea thickness acquires higher prognostic significance for the determination of the success of the operation and probable post-surgical complications. The objective of the survey is to measure the central corneal thickness of adult residents in Lithuania and the relevant factors having impact on it. In total 1650 residents of Lithuania in the age from 18 to 89 years of age were tested. The survey was carried out in the urban and regional primary health care institutions of the 10 counties of Lithuania and at the Centre of Eye Diseases of the Vilnius University Hospital Santariškių klinikos. The average central corneal thickness of men and women in Lithuania was defined in the survey. It was observed that central corneal thickness is neither conditioned by the gender, height or weight of an individual, nor by the eye refraction or the number and the size of corneal endothelia cells. The thickest cornea was observed in persons under 40 years of age, whereas it becomes thinner each decade from 2 to 8 µm after forty. It was identified in the survey that the thicker the cornea is - the smaller is its curvature. On the basis of the survey a table of central corneal thickness was developed for doctors ophthalmologists to be used in their... [to full text]Ragena – tai akies optinės sistemos dalis, nuo kurios būklės tiesiogiai priklauso regėjimas ir jo kokybė. Populiarėjant refrakcijos ydų korekcijai eksimeriniu lazeriu, ragenos centrinės dalies storis turi vis didesnę prognostinę reikšmę operacijos sėkmės bei pooperacinių komplikacijų galimybės nustatymui. Darbo tikslas – nustatyti Lietuvos suaugusių gyventojų ragenos centrinės dalies storį bei jį veikiančius veiksnius. Ištirta 1650 Lietuvos gyventojų nuo 18 iki 89 metų amžiaus.Tyrimas vykdytas 10 Lietuvos apskričių miestų ir rajonų pirminėse sveikatos priežiūros įstaigose, bei VUL Santariškių klinikos Akių ligų centre. Tyrimo metu nustatytas Lietuvoje gyvenančių vyrų ir moterų vidutinis ragenos centrinės dalies storis. Nustatyta, kad ragenos centrinės dalies storis nepriklauso nuo žmogaus lyties, ūgio, svorio, bei akių refrakcijos ir ragenos endotelio ląstelių skaičiaus ir dydžio. Storiausia ragena nustatoma iki 40 metų amžiaus, vyresniems nei 40 metų ji plonėja kas dešimtmetį nuo 2 iki 8 µm. Nustatyta, kad kuo storesnė ragena, tuo jos gaubtumas yra mažesnis. Tyrimo pagrindu sukurta skirtingo amžiaus žmonių ragenos centrinės dalies storio lentelė, kuria savo praktiniame darbe galės naudotis visi gydytojai oftalmologai.
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Jahjah, Walaa. "NanOstructures MultIferroïques INtrinsèques et extrinsèques : vers un contrôle Électrique des propriétés magnétiquEs (NOMINÉE) Influence of mesoporous or parasitic BiFeO3 structural state on the magnetization reversal in multiferroic BiFeO3/Ni81Fe19polycrystalline bilayers, in Journal of Applied Physics 124 (23), December 2018 Spin pumping as a generic probe for linear spin fluctuations: demonstration with ferromagnetic and antiferromagnetic orders, metallic and insulating electrical states, in Applied Physics Express 12(2), January 2019 Thickness dependence of magnetization reversal and magnetostriction in Fe81Ga19 thin films, in Physical Review Applied 12, August 2019." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0070.
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Nous menons trois études expérimentales du comportement de renversement de l’aimantation (RM) dans trois types différents de bicouches, et sous différents types de contraintes. Nous étudions l’influence sur les propriétés magnétiques de l’état structural du BiFe03, de contraintes mécaniques magnétoélastiques dans le Fe81Ga19, couplées ensuite à des contraintes électriques et même thermiques.Une bicouche polycristalline composée d’un ferromagnétique Ni81Fe19, et d’un multiferroïque intrinsèque BiFe03, est déposée par pulvérisation cathodique. Sa structure et sa morphologie sont caractérisées par diffraction des rayons X, et microscopie électronique à transmission, révélant deux états structuraux fondamentalement différents du BiFe03 dûs à des défauts. Le RM est analysé par magnétométrie à échantillon vibrant, fournissant des mesures angulaires à température ambiante. L’état parasité avec la phase parasite Bi2O3 augmente les valeurs du champ d’échange en fonction de la concentration de celle-ci, qui est contrôlable. Un état mésoporeux est aussi mis en évidence, et empêche l’établissement de l’anisotropie unidirectionnelle du couplage d’échange.Des couches minces magnétostrictives de Fe81Ga19 sont déposées sur des substrats de verre. Leurs caractérisations mettent en évidence une dépendance en épaisseur des propriétés magnétiques, en correspondance avec l’état structural.Deux directions cristallographiques remarquables pour toutes les épaisseurs permettent un RM cohérent. La couche la plus mince présente un coefficient de magnétostriction de 20 ppm, qui diminue pour les couches plus épaisses. Cette tendance est associée à une texture de surface prédominante qui se réduit au profit du volume polycristallin sans orientation préférentielle.De telles couches de Fe81Ga19 sont déposées sur des substrats monocristallins ferroélectriques de PMN-PZT pour former un multiferroïque extrinsèque. Le RM et le caractère d’anisotropie sont contrôlés par un champ électrique. Le composite révèle un fort couplage magnétoélectrique inverse entre les deux phases piézoélectrique et magnétostrictive, de valeur parmi les meilleurs rapportées à ce jour. Des mesures à basses températures montrent un effet magnéto-mécanique dû à la contrainte thermique et imposé par la nature du substratWe conducted three experimental studies of magnetization reversal (MR) behavior in three different types of bilayers, under different types of strain. We studied the influence on the magnetic properties of the structural state in the BiFe03, of magnetoelastic mechanical strain in the Fe81Ga19, which we then coupled to electrical and even thermal strainA bilayer consisted of using a ferromagnetic Ni81Fe19, and an intrinsic multiferroic BiFe03. These polycrystalline thin films are deposited by sputtering. Their structure and morphology are characterized by X-ray diffraction, and transmission electron microscopy, revealing two fundamentally different structural states of the BiFeO3 due to defects. The MR is analyzed by vibrating sample vector magnetometry, providing angular measurements it room temperature. The parasitic state with the parasitic phase Bi2O3 increases the values of the exchange field according to its concentration, which we can control. A mesoporous state is also highlighted, and prevents the establishment of the unidirectional anisotropy.Magnetostrictive thin films of Fe81Ga19 are deposited on glass substrates. Their characterizations reveal thicknessdependent magnetic properties, in correspondence with the structural state. Two remarkable crystallographic directions for the whole range of thicknesses allow a coherent MR. The thinner films have a magnetostriction coefficient value of 20 ppm, which decreases for the thicker films. This trend is associated with a predominant surface texture which is reduced in favor of the polycrystalline volume with non-preferential orientation.Such Fe81Ga19 films are deposited on single-cristalline ferroelectric substrates of PMN-PZT to form an extrinsic multiferroic.The MR and the anisotropy character are controlled by an electric field. The composite reveals a strong inverse magnetoelectric coupling αCME between the two piezoelectric and magnetostrictive phases, of value among the best reported so far. Measurements at low temperatures show a magnetomechanical effect due to thermal stress, and imposed by the nature of the substrate
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Akoussan, Komlan. "Modélisation et conception de structures composites viscoélastiques à haut pouvoir amortissant." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0188/document.
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L’objectif de ce travail est de développer des outils numériques utilisables dans la détermination de manière exacte des propriétés modales des structures sandwichs viscoélastiques composites au vue de la conception des structures sandwichs viscoélastiques légères mais à haut pouvoir amortissant. Pour cela nous avons tout d’abord développé un outil générique implémenté en Matlab pour la détermination des propriétés modales en vibration libre des plaques sandwichs viscoélastiques dont les faces sont en stratifié de plusieurs couches orientées dans diverses directions. L’intérêt de cet outil, basé sur une formulation éléments finis, réside dans sa capacité à prendre en compte l’anisotropie des couches composites, la non linéarité matérielle de la couche viscoélastique traduit par diverses lois viscoélastiques dépendant de la fréquence ainsi que diverses conditions aux limites. La résolution du problème aux valeurs propres non linéaires complexes se fait par le couplage entre la technique d’homotopie, la méthode asymptotique numérique et la différentiation automatique. Ensuite pour permettre une étude continue des effets d’un paramètre de modélisation sur les propriétés modales des sandwichs viscoélastiques, nous avons proposé une méthode générique de résolution de problème résiduel non linéaire aux valeurs propres complexes possédant en plus de la dépendance en fréquence introduite par la couche viscoélastique du coeur, la dépendance du paramètre de modélisation qui décrit un intervalle d’étude bien spécifique. Cette résolution est basée sur la méthode asymptotique numérique, la différentiation automatique, la technique d’homotopie et la continuation et prend en compte diverses lois viscoélastiques. Nous proposons après cela, deux formulations distinctes pour étudier les effets, sur les propriétés amortissantes, de deux paramètres de modélisation qui sont importants dans la conception de sandwichs viscoélastiques à haut pouvoir amortissement. Le premier est l’orientation des fibres des composites dans la référence du sandwich et le second est l’épaisseur des couches qui lorsqu’elles sont bien définies permettent d’obtenir non seulement des structures sandwichs à haut pouvoir amortissant mais très légères. Les équations fortement non linéaires aux valeurs propres complexes obtenues dans ces formulations sont résolues par la nouvelle méthode de résolution d’équation résiduelle développée. Des comparaisons avec des résultats discrets sont faites ainsi que les temps de calcul pour montrer non seulement l’utilité de ces deux formulations mais également celle de la méthode de résolution d’équations résiduelles non linéaires aux valeurs propres complexes à double dépendanceModeling and design of composite viscoelastic structures with high damping powerThe aim of this thesis is to develop numerical tools to determine accurately damping properties of composite sandwich structures for the design of lightweight viscoelastic sandwichs structures with high damping power. In a first step, we developed a generic tool implemented in Matlab for determining damping properties in free vibration of viscoelastic sandwich plates with laminate faces composed of multilayers. The advantage of this tool, which is based on a finite element formulation, is its ability to take into account the anisotropy of composite layers, the material non-linearity of the viscoelastic core induiced by the frequency-dependent viscoelastic laws and various boundary conditions . The nonlinear complex eigenvalues problem is solved by coupling homotopy technic, asymptotic numerical method and automatic differentiation. Then for the continuous study of a modeling parameter on damping properties of viscoelastic sandwichs, we proposed a generic method to solve the nonlinear residual complex eigenvalues problem which has in addition to the frequency dependence introduced by the viscoelastic core, a modeling parameter dependence that describes a very specific study interval. This resolution is based on asymptotic numerical method, automatic differentiation, homotopy technique and continuation technic and takes into account various viscoelastic laws. We propose after that, two separate formulations to study effects on the damping properties according to two modeling parameters which are important in the design of high viscoelastic sandwichs with high damping power. The first is laminate fibers orientation in the sandwich reference and the second is layers thickness which when they are well defined allow to obtain not only sandwich structures with high damping power but also very light. The highly nonlinear complex eigenvalues problems obtained in these formulations are solved by the new method of resolution of eigenvalue residual problem with two nonlinearity developed before. Comparisons with discrete results and computation time are made to show the usefulness of these two formulations and of the new method of solving nonlinear complex eigenvalues residual problem of two dependances
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Chen, Shuai-Yan, and 陳帥彥. "Thickness dependences of anisotropic tissues on polarized second harmonic imaging." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/248k48.
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碩士國立中山大學
醫學科技研究所
106
Second-harmonic generation (SHG) microscopy is a very useful technique for investigating the three-dimensional (3D) organization of anisotropic biological tissues, such as dermis, tendon and blood vessels. These are mainly composed of type-I collagen, which is structurally birefringent and of non-centrosymmetric structure, which can induce strong SHG signal. Therefore, this approach is suitable for clinical study as a non-invasive prediagnosis. However, large number of scattering events occurs between incident light and scattering particles in the tissue, hence it reduces the penetration depth of tissue and limits the application of SHG. It has been reported that the degree of polarization of circular polarized light maintains initial polarization state for deeper penetration depth than the linearly or elliptically polarized light, which has been stimulated with a polarization-sensitive Moten Carlo model; however, this work was only obtained by programing simulation. Therefore, related estimations need to be confirmed by optical microscopy experiments. In this work, we used a Ti:sapphire laser, providing the wavelength at around 810 nm to define three kinds of polarizations of incident beam, which are circular, elliptical and linear polarization. The forward SHG signal was obtained by PMT from pig’s tendon (30, 60, 100μm) and pig’s leather tissue (300, 600 and 700μm). It is confirmed that the longest to shortest penetration depth is in the sequence of circular (150μm), elliptical (143μm) and linear (121μm) polarization when penetrating into thick sample. The percentage of polarization deterioration of circular, elliptical and linear polarization in different thick sample: the change of linear polarization is the most significant (-99%), second is elliptical polarization (-75%), the change in circular polarization is 55% that is the lowest. Keyword: SHG, birefringent, non-central symmetric, polarized light, penetration depth
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Su, Yu-Ru, and 蘇郁儒. "Simulation and Analysis of InGaN p-n Single Junction and InGaN/Si p-n Double Junction Solar Cells with Indium Composition and Thickness Dependences." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/90922207226285283126.
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碩士國立高雄大學
應用物理學系碩士班
99
InxGa1-xN alloys feature a bandgap ranging from 0.7eV to 3.4eV, covering almost the entire solar spectrum. To optimize the efficiency and the best parameters of solar cells, numerical simulations of InGaN single junction and InGaN/Si double junction solar cells are conducted. The simulation modelling is important and indispensable for designing and fabricating InGaN single junction and InGaN/Si tandem solar cells. We changed the In composition and the thickness of the n- and p-InGaN to determine the short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), conversion efficiency (η), and power maximum (Pmax). First, for InGaN single junction solar cell, the Jsc, Voc, and FF have a strong dependence on the In composition. In composition is a critical parameter to determine Jsc, Voc, FF, and η of InGaN solar cells. In0.6Ga0.4N solar cell shows the maximum η ~ 22%. The band gap of In0.6Ga0.4N is 1.42 eV and is almost the same with GaAs. When the total layer thickness is greater than 500 nm, the absorption becomes saturated and the η increases smoothly. The simulation results are congruent with this trend. Second, the p- and n-junction thickness and In composition of InGaN junction are the key point to determine the characteristics of InGaN/Si double junction solar cell. The current matching should be considered in the InGaN/Si double junction solar cells. The smaller Jsc in each junction determines the total Jsc of InGaN/Si double junction solar cell. The total Voc is the sum of the Voc in each junction of InGaN/Si double junction solar cell. Because the current matching affects the Jsc, the curves of the FF have some turning points. The η increases with increasing In content and with dramatically drops with a turning point. With 100 nm p-type InGaN junction, the In0.6Ga0.4N/Si p-n double junction solar cell has the maximum η ~37%. The enhancement of the optimal η of In0.6Ga0.4N/Si p-n double junction solar cell is ~68% higher than that of In0.6Ga0.4N single junction solar cell. The total thickness of InGaN junction must be less than 500 nm, or the most light is absorbed in the InGaN junction and Si junction can not work. The simulation results could provide the clues for optimizing the device structures and process conditions of InGaN single junction and InGaN/Si tandem solar cells.
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Peng, Chin-Chuan, and 彭進詮. "Thickness dependence multiferroics property ofBi0.9Pb0.1FeO3 thin film." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/50363233463438336357.
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碩士國立中山大學
物理學系研究所
98
In this study, we study the annealing effect of Bi0.9Pb0.1FeO3 bulk in various time span and the various growth conditions of Bi0.9Pb0.1FeO3 thin film to physical proporties, such as crystal structure, surface amorphous, delectric properties. With these effort, this study wish to find a better growth condition for Bi0.9Pb0.1FeO3 film that exhibit the best ferroelectric property, and to understant the possible mechanism underlaying the growth conditions to the physical properties. It is found that the doping of Pb in Bi0.9Pb0.1FeO3 compound does stabalize the formation of single phase Bi0.9Pb0.1FeO3 ,however, this stabalization can only postpone the decay of Bi0.9Pb0.1FeO3 properties when is annealed in a long period of time. The crystal strucutre of Bi0.9Pb0.1FeO3 is very close to a pseudocubic structure in which oxgyen sites locate noncenter-symmetrically that generates a stronge electric polariztion. The various growth conditions has a very stong influence to the physical properties of Bi0.9Pb0.1FeO3 thin films. For those films grwon at 700oC exibits the best delectricity. The grain size of films grows as grwoth time as resutl of this the thicker the film thelarger the grain size. The electric hysterises property measured by PFM is observed for grain itself, however, the grain boundaries where accumulates many possible defects exhibits a large electric leakage therefore no saturated polarization is observed if a large area of electrode is used.
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Wu, Chrng-Fang, and 吳承芳. "Thickness dependence of electrical properties of reduced graphene oxides." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24643515613430215781.
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碩士國立交通大學
電子物理系所
101
The unique electrical properties of a real two-dimensional material, graphene, have attracted a lot of attentions since it was realized in 2004. The evolution from graphite to graphene has also been an interesting subject. Atomic force microscopy (AFM) and Raman spectrum have been, so far, the only two standard methods to identify layer number of the few-layer graphene (FLG). In this study, we use two different methods of electrical measurement for the determination of the layer number of FLG. We have observed a variation of resistivity at different temperature and conductivity at different bias voltage, and have investigated changes of physical properties with an increase of the layer number. Before the device fabrication, AFM is used to measure the thickness of the FLG for the estimation of the layer number. We use electron-beam lithography to make two types of devices for different electrical measurements. Type I devices are purely Ohmic-contacted devices. The metal electrodes are made by radio-frequency sputtering deposition. Type II devices are tunneling devices with a 8-nm thick aluminum oxide layer between metal (platinum) electrodes and a FLG. Resistivities of Type I devices are measured in the temperature range from 300 K to 30 K and the data are analyzed in accordance with the simple two band (STB) model. The layer dependent properties have been extracted through our analyses. When the layer number increases, the effective carrier mass, the electron-phonon interaction, and the density of state at Fermi level increase whereas the band overlap is kept constant. By analyzing our data from electrical measurements with the theoretical model, we have discovered alternatively other physical parameters which dependent strongly on the layer number of the FLG.
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Su, Po-Lung, and 蘇柏龍. "Thickness dependence of anomalous Nernst effect in ferromagnetic metals." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/75215231818259389434.
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碩士國立臺灣大學
應用物理研究所
104
The connection between thermoelectricity and spintronics has recently attracted much attention because of its potential application for the high-efficiency electric devices and the iste heat recycling. In particular, anomalous Nernst effect (ANE), the conversion of thermal energy into the spin-dependent electric signal in ferromagnetic metals(FMs), is one of the most important mechanism to study the coupling between charge, spin, and heat. Although, the spintronic devices based on the ANE, including the multilayer structure and ferromagnetic thermal thermopile, have been extensively investigate, the issue for the thickness dependence of ANE has never been addressed. In this work, by using a vertical temperature gradient, we systematically study the thickness dependence of the ANE in several ferromagnetic metals (FMs), including permalloy (Py), iron (Fe), and cobalt (Co) at room temperature. The sign of the ANE can immediately tell that the sign of the Nernst angle in Fe is opposite to that of Py and Co. In the thickness-dependent measurement, we report that the ANE signal in all FMs samples are constant in thick films region while the signal decreases with decreasing thicknesses (less than 10 nm, except for ultra-thin Fe). Importantly, there is no measurable ANE signal when thickness is less than 2 nm, even the ferromagnetic ordering with Curie temperatures still above room temperature. After taking the thickness dependence of the resistivity and magnetization into account, we are able to determine the intrinsic ANE coefficient in ferromagnetic metals for the first time. More surprisingly, we observed the sign change of ANE signal between thick and thin Fe samples. In addition, unlike other FMs, the ANE voltage showed increased instead of decreased signal, when the thickness of Fe sample is less than 6 nm. We suggest this enhancement signal is origin from the intrinsic property of ultra-thin Fe film. Our results provide an important insight on how the role of thickness effect has a strong influence on the development of multilayer structure or ferromagnetic thermal thermopile devices.
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Fahmi, Fariz Rifqi Zul, and 法日棋. "Thickness Dependence of MoS2 Ultrathin Film for CO2 Photo-reduction." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/6f4656.
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碩士國立臺灣科技大學
材料科學與工程系
106
Two Dimensional (2D) materials offer a new opportunity to explore fundamental physics and overcome the scaling limit of bulk materials. The most extensively studied materials are 2H phase in group VI TMDCs such as molybdenum disulfide (MoS2). MoS2 is one of TMDs with adjustable optical properties by tuning the layer number. Bulk MoS2 has an indirect bandgap, which increases monotonically as the number of layer decreases. This ability makes MoS2 as a promising material for photocatalytic CO2 reduction. Light absorption performance is one of the keys to determine the performance metric of the photo-catalyst for CO2 photo-reduction. This thesis studies MoS2 ultrathin film for CO2 photo-reduction. To make CO2 photo-reduction happen, there are 6 important factors to be considered. Bandgap (Absorption), charge separation and transportation, band position vs redox potential, reaction between adsorbed species and charge carries, adsorption of chemical species on the photo-catalyst surface, and desorption of chemical products. This thesis is to investigate the thickness dependence and substrate effect on the CO2 reduction of MoS2. MoS2 ultrathin film was successfully prepared by post sulfurization. First step was to deposit MoO3 then converted to MoO2 and sulfurized into MoS2. AFM confirm the thickness, were named as MS3, MS7, and MS17 corresponding to the original oxide layer of 3 nm, 7 nm, 17 nm and 25 nm. UV visible measurement was performed to find out the bandgap and absorption property. From tauc plot calculated from absorbance data, the bandgap are 1.7 eV, 1.65 eV and 1.58 eV, and the absorption performance are 10%, 12% and 30% for MS3, MS7 and MS17 respectively. Raman Spectroscopy confirm the frequency differences between A1g and E2g1 with 23.27, 24.76, 25.76 and 26.24 cm-1 are for MS3, MS7, MS17 and bulk respectively. The grain size was ranging from 40 to 235Å. The gas chromatography has been performed to understand the productivity and selectivity. 2 x 2 sample inserted to the 7 cm3 chamber with nitrogen, CO2 and H2O entered later. From the GC measurement, 3 products obtained from all samples are methane (0.095 µmole), acetaldehyde (0.12 µmole) and acetone (0.04 µmole). From the thickness dependent measurement, the production rate increase proportional to increased thickness but decreases after exceeding 17 nm. The production rate also revealed if the C1 product not sensitive to thickness inversely proportional with C2 and C3 product. Finally, MoS2 ultrathin film successfully demonstrated for CO2 photo-reduction. Thickness dependent and substrate effect play a role for selectivity and productivity. Detailed mechanism need further investigation.
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Lu, Hong-Bin, and 盧宏斌. "Thickness Dependence of Two Resonance Modes in NiFe/CoFe Bilayer." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/rqmmn7.
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碩士國立臺灣大學
物理學研究所
107
In our findings, when total thickness of NiFe/CoFe bilayer is ≧48.5 nm and frequency > 8 GHz, two ferromagnetic resonance peaks, which are called optical mode and acoustic mode, can be observed. The relation of exchange coupling field (H_ex) of optical mode and thickness of CoFe and NiFe is that when NiFe thickness is fixed at 43.5 nm and we vary CoFe thickness, H_ex ∝ t_CoFe to the power of -0.6; when CoFe thickness is fixed at 30 nm and we vary NiFe thickness, H_ex ∝ t_NiFe to the power of -1.88. By analyzing H_ex and effective magnetization (M_eff), it is found that in optical mode, FMR signal is mainly contributed by CoFe, and the large H_ex can be explained by standing spin wave. In acoustic mode, when NiFe is thicker than 28.5 nm, FMR M_eff is mainly contributed by NiFe; when NiFe is thinner than 28.5 nm, FMR M_eff is contributed by NiFe and CoFe. H_ex is attributed to interface magnetization pinning, which provides a field that is parallel to the orientation of magnetization[1]. H_ex of acoustic mode increases with CoFe and NiFe thickness. The change of absorption peak amplitude with frequency meets previous theoretical calculation, and this behavior can be explained by skin effect of microwave in conductor[2]. The results of hysteresis loops show that the saturation magnetization Ms and coercivity Hc of different thickness do not fit well with the theory, but follow similar trends.
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Ijaduola, Anota Oluwatoyin. "AC loss and thickness dependence of critical currents in coated conductors." 2005. http://etd.utk.edu/2005/IjaduolaAnota.pdf.
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Liou, Shang-sheng, and 劉尚昇. "Thickness dependence of domain wall energy in Fe-Ni thin films." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/52137723979331992897.
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碩士輔仁大學
物理學系
84
The application of Fe-Ni thin films as computer memory and logic elements isvery valuable and has been studied extensively in recent years. For the composition of Fe20Ni80, also known as Permalloy, it is the most remarkableone. With the method of thermal evaporation, we have made Fe-Ni thin films invarious thickness ranges and in neighboring compositions around that of Permalloy for domain observation and other experiments. The thickness of thin films was determined by Dektak3, a depth profile measuring system. The real composition of thin films was measured with SEM-EDS(Scanning Electron Microscopy - Energy Dispersive X-ray Spectrometer). The observation of domain structure and domain walls in thin films was made by the Bitter pattern method. From experimental data and theoretical calculations, we have studied the thickness and composition dependence of domain wall energy respectively. It wasfound that the domain wall energy density of Fe-Ni thin films is about 1-20 erg/cm2. For the case of Permalloy, our experimental data about the film thickness dependence of domain wall energy are in agreement with that from theoretical predictions. In the case of other compositions, the minimum value of domain wall energy is around the composition of Permalloy.
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Ye, Shi-Cheng, and 葉士誠. "Thickness and width dependence of diffraction efficiency in gold binary gratings." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/42406697356052639561.
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碩士國立交通大學
照明與能源光電研究所
104
Planar photonics with binary grating draws immense attention because of characteristics that allow for controlling the flow of light beyond that offered by natural material. Binary gratings are gratings of various widths in the 2880 nm period. The grating’s resonance wavelength is tunable by changing the thickness of the binary grating. This also allows for an optimized efficiency of diffraction. In addition, normal incidence with the transmission-type binary grating is discussed. Based on the anomalous refraction results, it is possible to realize binary grating devices with optimized dimensions in the visible to near-infrared (NIR) wavelength region.
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Chen, Guan-Lin, and 陳冠霖. "Optoelectronic Properties of i-Layer Thickness Dependence Single Junction Solar Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30452104507069109923.
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碩士中原大學
電子工程研究所
100
In this thesis, we reported the optoelectronic characteristics of p-i-n GaAs solar cells. We studied the optimum thickness of intrinsic layer for obtaining the highest conversion efficiency. The samples without were detected by current-voltage measurement under AM1.5G illumination that the sample with 1 nm intrinsic layer has the highest efficiency of 14.24％. Based on low temperature photoluminescence and time resolved photoluminescence measurement, localization depth in such intrinsic layer thickness was developed. The experimental result showed that both localization depth (Eloc) at 9.8 meV and radiative lifetime (τrad) at 5.3 ns were achieved the best optoelectronic performance in 1 nm intrinsic layer. It was found out that the localization formed due to Zn diffusion in n-GaAs and intrinsic layer. Different samples annealed at 650℃ with different annealing time were attained to obtain the localization depth. It was clearly revealed that the longer annealed time, leads to the deeper localization, and to the shorter life time. The ECV measurements manifest that the Zn concentrations are changed dramatically. The evidence shows clearly that the Zn presented nominally in the lower n-GaAs and i-GaAs layer, as the result of diffusion. Furthermore, it was proposed to distinguish the front surface recombination velocity from the induced defects by variation the PL intensity. From this photoluminescence measurement, the surface recombination velocity of the solar cells with the intrinsic layer 1 nm is obviously improved. As these results, the thickness of intrinsic layer indeed deeply influences the efficiency of solar cell.
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Duan, Guangwu. "Terahertz metamaterial devices: from thickness and material dependence to perfect absorption." Thesis, 2018. https://hdl.handle.net/2144/32076.
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Metamaterials consist of subwavelength unit cells periodically patterned to exhibit extraordinary electromagnetic properties that do not exist in naturally occurring materials. The far-infrared, or terahertz frequency region of the electromagnetic spectrum is ripe with potential with metamaterials providing a promising technological route towards developing application. Metamaterial “perfect absorbers”, typically configured with three layers as metamaterials-dielectric-ground, have attracted tremendous interest due to near unity absorption of incident electromagnetic radiation over a designed frequency range, with the device having subwavelength thickness. Several theories have been developed to understand the physics of perfect absorption. However, it is important to develop alternative numerical and analytical strategies that transparently connect with the electromagnetic and dielectric properties of the constituent materials to better understand how experimentally accessible parameters ultimately determine the absorption.
First, this dissertation introduces a metamaterial absorber with air as spacer layer instead of dielectric materials. In the absence of dielectric material loss, the design can achieve three times higher quality factor compared to traditional designs. Additionally, the absence of the spacer material yields the possibility to access the space between the metamaterial layer and the ground plane inspiring a microfluidic channel integrated sensing device with sensitivity more than three times of the reported results. Second, this dissertation investigates the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. We observed that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with the analysis. Third, this dissertation presents a detailed analysis of the conditions that result in unity absorption in metamaterial absorbers. These simple expressions reveal a redshift of the unity absorption frequency with increasing loss that, in turn, necessitates an increase in the thickness of the dielectric spacer. Our findings can be widely applied to guide the design and optimization of the metamaterial absorbers and sensors.
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Lu, Wei-Yi, and 呂威毅. "Raman Scattering of i-Layer Thickness Dependence GaAs Single Junction Solar Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/04836958785003244172.
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碩士中原大學
電子工程研究所
100
In this thesis we studied the Raman scattering of p-i-n gallium arsenide (GaAs) solar cells with different thicknesses of intrinsic layer. In Raman scattering, used a spatial correlation (SC) model we can explained the correlation length (L) and asymmetry of the longitudinal-optic phonon Raman spectrum. We found the sample with 1 nm thickness of intrinsic layer had the highest correlation length and symmetry. And from current-voltage measurement under AM1.5G illumination that find the highest conversion efficiency (η) in the same sample. Different annealing times 0, 5, 10, 20, 30 and 60 seconds are held at 650 oC in the intrinsic layer 1 nm. symmetric ratio and correlation length are decreased when annealing time is kept from0 to 60 sec. To verify Zn diffusion into the i-layer and base region. We used electrochemical capacitance voltage (ECV) measurement that observe the carrier concentration increased at intrinsic layer and the base region for 60 sec when annealed the 1 nm i-layer GaAs solar cell. The details of the experimental results and the application feasibility of Raman scattering of p-i-n gallium arsenide (GaAs) solar cells with different thicknesses of intrinsic layer in this thesis.
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Hsu, Chen-Chia, and 許展嘉. "Thickness dependence on the resistive switching properties of NiO/HfO2 thin films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/35pxsh.
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碩士國立東華大學
物理學系
106
In this study, we prepared a sandwich resistive-switching device of NiO/HfO2@SiO2/Si. The first layers of HfO2 thin films was synthesized by hot-filament metal-oxide vapor deposition (HFMOVD) technique with various synthesis temperatures, which were 1600, 1650, 1700, 1750, and 1800 °C, respectively. The second layers of NiO thin films were synthesized by radio-frequency magnetron sputtering deposition (RFMSD) technique. Through the secondary electron (SE) and backscattered electron (BE) signals of the field-emission scanning electron microscopy (FESEM), the morphology and thickness of the HfO2 and NiO thin films can be determined. The crystallinity of HfO2 and NiO thin films were examined by X-ray diffractometry (XRD). The resistive switching properties of the NiO/HfO2@SiO2/Si device were probed using an IV loop method. The NiO/HfO2@SiO2/Si device possesses the two unipolar and bipolar characteristics.
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Chen, Rong Po, and 陳榮波. "Thickness dependence of crystallization properties in Ge40Sb10Te45Se5-x (Ag,Pb,Ti) x films." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/18996339859216399270.
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温國宏. "Films Thickness Dependence of Ferroelectric and Photovoltaic Properties of Calcium Doped Bismuth Ferrite." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/47260632657294266642.
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碩士國立新竹教育大學
應用科學系碩士班
103
In this experiment, the photovoltaic effect with different film thickness of 5% Ca doped BiFeO3 thin films were investigated. The probable physical mechanism were carried out many different measurements which may affect the efficiency of the photovoltaic effect. The specimen of BFO thin films and the electrode were all deposited on Si(100) by RF magnetron sputtering. First, we grew LaNiO3 on Si(100) at 450 . Second, The 5% Ca doped BiFeO3 films were deposited on LaNiO3. Third, we deposited Pt or AZO to do measurements, respectively. Film thickness was estimated by SEM and X-ray reflectivity. Film crystallinity was carried out by X-ray diffraction measurement. The morphology was measured by atomic force microscope and X-ray reflectivity. The hysteresis loop was performed by TF-2000 and the photovoltaic effect were measured by 405 nm laser. BFO was (100) highly preferred along Si (100) substrate from X-ray diffraction measurement. BFO film strain relax as film thickness increase, hence the diffraction peak position shift more close to the expected bulk value. The surface roughness, which was carried out by AFM and X-ray reflectivity has little increase as film thickness thicker. The hysteresis loop showed that the polarization slow down as the film thickness increased. The photovoltaic effect also slow down as the film thicker. The BFO built-in electric field affect the efficiency of photovoltaic effect. As the film thickness increased to 100 nm, the strain relax caused built-in electric field become weaker and the probability of electron and hole recombined increase due to distance between two electrode; therefore, the efficiency of photovoltaic hidden.
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Wu, chun-hsien, and 吳俊賢. "Films Thickness Dependence of Ferroelectric and Photovoltaic Properties of Lanthanum Doped Bismuth Ferrite." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/18060275025942903027.
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碩士國立新竹教育大學
應用科學系碩士班
103
The photovoltaic effect was discussed under different thickness of Lanthanum doped BiFeO3 thin film. Thin film were deposited by RF-sputtering.First,LaNiO3 (LNO) was deposited on Si(100) substrate, then BiFeO3 was grown on LNO. The top electrode used aluminum doped zinc oxide (AZO). BFO thickness have 25, 50, 75, 100 and 150 nm, respectively, and the thickness was calibrated by X-ray reflectivity and field emission scanning electron microscopy. Surface roughness was carried out by atomic force microscopy. Lanthanum doped BFO have strain relaxation with film thickness increase which was observed from the peak position shift of theta-two theta scan of X-ray diffraction. As the film thickness increase, the dipole moment decrease and the built-in electric field decrease. The probability of electron-hole recombination become higher as the built-in electric field become smaller; therefore, the efficiency of photovoltaic effect become smaller. The polarization effect played an important role for efficiency of photovoltaic. As the film thickness increase, the resistance has a dramatic increase that dominate the efficiency of photovoltaic more than the polarization effect dominate. The efficiency of photovoltaic do not have straight correlation with film crystallinity, surface roughness, transmittance and leakage current by various measurements under different film thickness.
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Hung, Po-An, and 洪伯安. "Exploring Thickness Dependence on Electrical Properties of ReSe2 Flakes by Scanning Probe Microscope." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/35msbn.
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碩士國立交通大學
電子物理系所
105
In order to scale down electronic devices, scientists have paid much attention to new materials of two-dimensional (2D) materials like graphene and MoS2. In this experiment, we explore thickness dependency of electronic structures of the 2D material - rhenium diselenide (ReSe2) by scanning tunneling microscope (STM). We adopt mechanical exfoliation to disperse ReSe2 flakes on indium tin oxide (ITO) conductive glass. The morphology and the electronic structures of these ReSe2 flakes are investigated by STM and scanning tunneling spectroscopy (STS). The dependency between thickness and electronic structures of ReSe2 flakes is studied. In the beginning, we check the ITO surfaces. We find that the surface of the ITO conductive glass consists of islands which are formed by aggregated grains. Further, the STS measurements show that there are no bandgaps on the ITO surface. On the other hand, we observe flat surfaces on thick ReSe2 flakes and clear bandgaps on their surface. We also check surface morphology using atomic force microscope (AFM) and get the same conclusions. Finally, we learn that the thinner the thickness of ReSe2 is, the larger the bandgap of ReSe2 will be. The dependency of the bandgap of ReSe2 flakes on their thickness is qualitatively consistent with theoretical calculations.
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Wu, Jiunn-Pey, and 吳俊沛. "Analysis on Gate-Oxide Thickness Dependence of Hot-Carrier- Induced Degradation in Submicrometer LDD nMOSFET's." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/44807502258254042698.
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碩士國立交通大學
電子研究所
83
In this thesis, gate-oxide thickness dependecnce of hot- carrier-induced degradation is investigated for LDD nMOSFET' s. It is shown that a thinner gate oxide LDD nMOSFET's causes larger drain current degradation under the same bias stress condition. However, it has been reported that a thinner gate oxide conventional nMOSFET shows smaller degradation. Since the dominant degradation mechanism for the LDD device differ from the conventional device, due to the spacer-induced degradation, an improved drain linear-current degradation model is developed in order to investigate the degradation mechanism in LDD MOSFET. A new degradation mechanism is introduced to account for the increasing of resistance in the n- region due to the generation of interface states. Further, since the effective channel length and the source-drain series resistance of an LDD device are gate-voltage dependent, the paired Vg method is used to extract the effective channel length and the series resistance. It can be found that this generalized drain current degradation model gives a good agreement to the measured data for different gate oxide thickness. Based on this model, the gate-oxide thickness dependence of degradation can be well analyzed.
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Tai, Hung-lin, and 戴宏霖. "In-Situ Probing Thickness Dependence of the Electrical Characteristics of Pentacene- Based Field-Effect Transistors." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/62004769033970741270.
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碩士國立臺灣科技大學
電子工程系
98
The pentacene field-effect transistors were studied as a function of molecular monolayer(ML) with in-situ electrical measurement. Field-effect mobility occurs in one thin monolayer(~ 1.57 nm) in high vacuum. Carrier mobility dramatically increases with increasing thickness and surface coverage until saturation thickness (3.2 ML). Beyond the key of saturation thickness, no more effective charge carriers contribute to conducting channel. The atomic force microscopy images of the pentacene layer show the Stranski-Krastanov growth mechanism; molecules change their growth direction from lateral to vertical. The growth quality of first few pentacene is strongly related to insulator material and influences the morphology, molecular packing, and electrical characterization in this research.
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"Thickness dependence of electron transport in amorphous selenium for use in direct conversion flat panel X-ray detectors." Thesis, 2013. http://hdl.handle.net/10388/ETD-2013-04-950.
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Abstract
Amorphous Selenium (a-Se) was first commercialized for use as a photoconductor in xerography during the middle of the twentieth century. Since then the hole transport properties of a-Se have been studied extensively, however the study of electron transport remains relatively limited. Flat panel digital X-ray detectors using a-Se as a photoconductor have been developed and are being used in mammographic screening. The charge transport properties of the photoconductor layer will in part determine the performance of the flat panel detector. X-ray absorption causes electron-hole pair generation in the bulk of the photoconductor, requiring both electrons and holes to drift across the sample and be collected. If these carriers are lost in the many localized trapping states as they cross the sample, they will not contribute to the image signal resulting in unnecessary radiation exposure to the patient.
Eleven a-Se samples were deposited at the University of Saskatchewan varying in thickness from 13 μm to 501 μm. Pure a-Se was chosen to ensure uniformity across the thickness of the samples, that is, to ensure the composition of the film did not change across the thickness. Time of flight transient photoconductivity experiments (TOF) and interrupted field time of flight (IFTOF) measurements were performed to measure the electron drift mobility and lifetime respectively. The product of electron drift mobility μ and lifetime τ, hence the carrier range (μτ) at a given applied electric field. The electron range is an important parameter as this places limits on the practical thickness of the photoconducting layer in a detector. This study also includes an investigation into the effect of the definition of transit time on the calculated drift mobility and analysis of the dispersive transport properties of a-Se.
It was observed that as sample thickness (L) increased, electron drift mobility (μ) decreased. In addition electron lifetime (τ) decreased dramatically in samples thinner than 50 μm. Electron range (μτ) was 2.26 × 〖10〗^(-6) cm^2/V in the 147μm sample and 5.46 × 〖10〗^(-8) cm^2/V in the 13 μm sample, a difference of almost two orders of magnitude. The comparison of the half current method and inflection point methods to calculate the transit time of the same TOF curve, shows that the calculated mobility can vary by as much as 24%. This illustrates clearly that it is important to use the same point on the TOF curve to define the transit time. Charge packet dispersion (spread) in the time domain in pure a-Se samples was proportional to L^m where L is the photoconductor thickness and m ~ 1.3, measured at both 1 V/μm and 4 V/μm.
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"Thickness dependence and doping effect on transport properties of post-hydrogenated amorphous silicon films prepared by vacuum evaporation." Chinese University of Hong Kong, 1988. http://library.cuhk.edu.hk/record=b5885954.
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Lin, Shih-Chieh, and 林士傑. "InAs Thickness Dependence of Carrier Emission and Capture from Defects in InAs/InGaAs dots-in-a-well Structure." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/v7tn8u.
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碩士國立交通大學
電子物理系所
92
In this study, we have investigated the InAs/InGaAs (dots-in-a -well) structure with different InAs thickness . Red shift of Photoluminescence (PL) spectroscopy is observed from 1238nm to 1310nm as the InAs thickness increases from 1.97 to 2.7 ML. A significant reduction of the PL intensity is accompanied with a blue shift for 3.06 ML and 3.33 ML samples, indicating that there is a critical thickness in the InAs growth. The capacitance-voltage (C-V) measurement shows a carrier confinement for 2.34 ML sample. With increasing the InAs thickness to 3.06 and 3.33 ML, a significant carrier depletion caused by relaxation is observed near the bottom InAs/GaAs interface. Traps at 0.37eV and 0.41eV are measured by DLTS in 3.06 ML and 3.33 ML samples, respectively. These two traps are suggested to cause the carrier depletion. DLTS measurements have also provided an evidence of the capture barriers Eσ=0.1eV and Eσ=0.22eV for 3.06 ML and 3.33 ML samples, respectively.
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Shyuh, Kai-Ting, and 頊凱婷. "The Institutional Thickness and Path Dependence in Nanzih Export Processing Zone ─The case of Semiconductor Packaging and Testing Industry." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/tg4kd9.
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碩士國立高雄師範大學
地理學系
101
There are many studies about "industry cluster" in Taiwan, but most of them are around the theme of "geographic proximity". As a matter of fact, "people" and "institution" are more dependent on the exchange in the real economic environment. This situation decreases the cost ratio of production decline and, increases the social cost. Even in a similar environment and material conditions, due to the different evolution in "institutional change" and "path dependence", the development of regions will develop into distinct spatial structure. This paper uses "the packaging and testing industry of semiconductor industries in Nanzih Export Processing Zone (NEPZ)" as the research object: the formal institutions, informal institutions and path dependence affect the growth mechanism of self-local innovation? The research investigation has begun in July, 2011 until now. The interviewees include the Export Processing Zone Administration and the firms of packaging and testing industry. The study result, we found: the cluster effect about the packaging and testing industry, which surround by Advanced Semiconductor Engineering (ASE) and Orient Semiconductor Electronics (OSE), is formed by the production network in Nanzih. And different size firms which have different business thinking will dominate their degree of vibrant economy. Otherwise, the long-term evolution of the export processing zone institution attracts industry to the area. Not only can the firms save the expenses of land and factory building but also they can focus on developing their business. The guidance from policy and trust from private network will promote the packaging and testing industry in NEPZ to flourish.
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Murphy, Theresa. "FACTORS INFLUENCING IMPACT OF BIOLOGICAL CONTROL AGENTS OF THE EMERALD ASH BORER." 2017. https://scholarworks.umass.edu/masters_theses_2/479.
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Agrilus planipennis, the emerald ash borer (EAB), is a destructive invasive forest pest decimating North American ash trees. Population-wide management of EAB focuses on biological control, with the introduction of four parasitic wasps; one egg parasitoid, Oobius agrili and three larval parasitoids- Spathius galinae, Spathius agrili and Tetrastichus planipennisi. This thesis examines some of the factors influencing the establishment of these larval biocontrol agents. Chapter 1 examines the relationship between woodpeckers and the parasitoids S. agrili and T. planipennisi. Both woodpeckers and these parasitoids attack the larval stage of EAB, which means their impacts overlap and potentially interact. To examine this relationship, I established parasitized larvae on ash trees and then used screening to exclude woodpeckers from some sections of the tree. Results show that while there is no evidence of discriminatory feeding for or against parasitized larvae, the presence of parasitized larvae changes woodpecker feeding behavior at a stand-level. I hypothesize that this change is due to these larval parasitoids being a low-food reward and that parasitism contributes to a change and decrease in patch quality, causing woodpeckers to quit foraging sooner than usual.
My second chapter focuses on Spathius galinae, which was recently approved for release in the north central and northeastern US in 2015, to provide additional population control. Spathius galinae’s long ovipositor (4-5.3mm) is theoretically expected to help target EAB in ash with larger diameters and bark thicknesses. Using experimentally infested logs of varying thicknesses in the laboratory I tested the limits and preferences for oviposition of S. galinae, to understand its potential impact on EAB. My results demonstrated that although parasitism by S. galinae drops significantly when bark thickness reaches 8 mm, this prevents S. galinae only from reaching EAB larvae in my largest ash trees (S. galinae will play a vital role in providing additional control and in supporting ash regeneration in aftermath areas of EAB invasions.
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Teo, L. W., Van Tai Ho, M. S. Tay, Wee Kiong Choi, Wai Kin Chim, Dimitri A. Antoniadis, and Eugene A. Fitzgerald. "Dependence of nanocrystal formation and charge storage/retention performance of a tri-layer memory structure on germanium concentration and tunnel oxide thickness." 2003. http://hdl.handle.net/1721.1/3799.
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The effect of germanium (Ge) concentration and the rapid thermal oxide (RTO) layer thickness on the nanocrystal formation and charge storage/retention capability of a trilayer metal-insulator-semiconductor device was studied. We found that the RTO and the capping oxide layers were not totally effective in confining the Ge nanocrystals in the middle layer when a pure Ge middle layer was used for the formation of nanocrystals. From the transmission electron microscopy and secondary ion mass spectroscopy results, a significant diffusion of Ge atoms through the RTO and into the silicon (Si) substrate was observed when the RTO layer thickness was reduced to 2.5 nm. This resulted in no (or very few) nanocrystals formed in the system. For devices with a Ge+SiO₂ co-sputtered middle layer (i.e., lower Ge concentration), a higher charge storage capability was obtained than with devices with a thinner RTO layer, and the charge retention time was found to be less than in devices with a thicker RTO layer.Singapore-MIT Alliance (SMA)
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Wen, Je-min, and 溫哲民. "In-Situ real time Probing Thickness Dependence of the Electrical Characteristics of n-type, p-type Organic Field-Effect Transistors and manufacture CMOS inverter." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/87101875686706742628.
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碩士國立臺灣科技大學
電子工程系
100
This thesis has report an in situ and real-time measurement method for the electrical characteristic evolution of n-type (N,N’-dipentadecafluorooctyl-1,4,5,8-naphtalene tetracarboxylic Diimide, NTCDI-C8F15) and p-type (pentacene) organic thin film transistors (OTFTs) during the deposition of organic thin film. In the first part, we analyze the thickness dependence of pentacene OTFTs where grown the thin film at different deposition rate (0.01, 0.03 and 0.1 nm/s) on the bottom contact substrate at room temperature. We demonstrate that the carrier transport in pentacene OTFTs is strongly affected by the quality of surface coverage in the first few monolayers. In addition, at our optimum deposition rate of 0.03 nm/s, we obtained a hole mobility of 0.21 cm2/Vs better than slow (0.01 nm/s) and fast (0.1 nm/s) rates. We speculate that this improvement of hole mobility is due to the increased surface coverage on the insulator, resulting in improving probability of charge percolation in the channel. In the second part, we study the thickness dependence of the purified and non-purified pentacene respectively. We found that the field-effect phenomenon could be observed less than 1 ML (~1.54 nm) for the purified pentacene and the hole mobility is improved to 0.24 cm2/V s. With the use of atomic force microscope (AFM) measurement, the purified pentacene exhibits larger grain size and better film coverage, indicating the better crystallinity of the purified pentacene that is mainly from the absence of the impurities. It has demonstrated that the growth mechanism of the first few monolayers plays an important role in the electrical characteristic of organic thin film transistors. In the third part has presented thickness dependence of n-type (NTCDI-C8F15) organic field-effect transistors. The electron mobility of the device as thin as 2 MLs has been determined. The saturation thickness (d0) is 3.5 MLs. Atomic force microscope revealed that, island mode growth mechanism of NTCDI-C8F15 with near upright position stacking on substrate has been confirmed, is because of the fluorophobic effect of the material According to the aforementioned, we conclude the thin film growth quality in first few monolayer is the most important issue for organic thin film transistors, although different materials have different electrical characteristics and saturation thickness (d0). We adjusted the best process parameter from these three experiments. Finally, we demonstrated a complementary inverter by using these two materials (pentacene and NTCDI-C8F15) and attained the value of gain at 8, which was similar to literatures.
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Song, T. L., Soo-Jin Chua, Eugene A. Fitzgerald, Peng Chen, and S. Tripathy. "Plastic Relaxation In Single InᵡGa₁âᵡN/GaN Epilayers Grown On Sapphire." 2003. http://hdl.handle.net/1721.1/3839.
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Plastic relaxation was observed in InᵡGa₁âᵡN/GaN epilayers grown on c-plane sapphire substrates. The relaxation obeys the universal hyperbolic relation between the strain and the reciprocal of the layer thickness. Plastic relaxation in this material system reveals that there is no discontinuous relaxation at critical thickness and once a layer starts to relieve, it follows the same strain-thickness dependence, unconstrained by the original misfit until the material system work hardens. From x-ray diffraction calibration, the in-plane and normal relaxation constants KP0 and KN0 for the InᵡGa₁âᵡN/GaN grown on sapphire were found to be â0.98 ± 0.03 and +0.51 ± 0.03 nm, respectively.Singapore-MIT Alliance (SMA)