To see the other types of publications on this topic, follow the link: Silicon-carbide thin films.
Dissertations / Theses on the topic 'Silicon-carbide thin films'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Silicon-carbide thin films.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Deva, Reddy Jayadeep. "Mechanical properties of Silicon Carbide (SiC) thin films." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002615.
Full text
2
Deva, Reddy Jayadeep. "Mechanical Properties of Silicon Carbide (SiC) Thin Films." Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/210.
Full textAbstract:
There is a technological need for hard thin films with high elastic modulus. Silicon Carbide (SiC) fulfills such requirements with a variety of applications in high temperature and MEMS devices. A detailed study of SiC thin films mechanical properties was performed by means of nanoindentation. The report is on the comparative studies of the mechanical properties of epitaxially grown cubic (3C) single crystalline and polycrystalline SiC thin films on Si substrates. The thickness of both the Single and polycrystalline SiC samples were around 1-2 µm. Under indentation loads below 500 µ-Newton both films exhibit Elastic contact without plastic deformation. Based on the nanoindentation results polycrystalline SiC thin films have an elastic modulus and hardness of 422 plus or minus 16 GPa and 32.69 plus or minus 3.218 GPa respectively, while single crystalline SiC films elastic modulus and hardness of 410 plus or minus 3.18 Gpa and 30 plus or minus 2.8 Gpa respectively. Fracture toughness experiments were also carried out using the nanoindentation technique and values were measured to be 1.48 plus or minus 0.6 GPa for polycrystalline SiC and 1.58 plus or minus 0.5 GPa for single crystal SiC, respectively. These results show that both polycrystalline SiC thin films and single crystal SiC more or less have similar properties. Hence both single crystal and polycrystalline SiC thin films have the capability of becoming strong contenders for MEMS applications, as well as hard and protective coatings for cutting tools and coatings for MEMS devices.
3
Raghavan, Srikanth. "Comparative studies of 6H-SiC surface preparation." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5766.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains xii, 56 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-53).
4
Ziemer, Katherine S. "Studies of the initial stage of silicon carbide growth on silicon." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1815.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xvi, 217, 2 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 198-207).
5
Dusatko, Tomas A. "Silicon carbide RF-MEM resonators." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100250.
Full textAbstract:
A low-temperature (<300°C) method to fabricate electrostatically actuated microelectromechanical (MEM) clamped-clamped beam resonators has been developed. It utilizes an amorphous silicon carbide (SiC) structural layer and a thin polyimide spacer. The resonator beam is constructed by DC sputtering a tri-layer composite of low-stress SiC and aluminum over the thin polyimide sacrificial layer, and is then released using a microwave O 2 plasma etch. Deposition parameters have been optimized to yield low-stress films (<50MPa), in order to minimize the chance of stress-induced buckling or fracture in both the SiC and aluminum. Characterization of the deposited SiC was performed using several different techniques including scanning electron microscopy, EDX and XRD.Several different clamped-clamped beam resonator designs were successfully fabricated and tested using a custom built vacuum system, with measured frequencies ranging from 5MHz to 25MHz. A novel thermal tuning method is also demonstrated, using integrated heaters directly on the resonant structure to exploit the temperature dependence of the Young's modulus and thermally induced stresses.
6
Khoele, Joshua Relebogile. "Deposition and structural properties of silicon carbide thin films for solar cell applications." University of the Western Cape, 2014. http://hdl.handle.net/11394/4345.
Full textAbstract:
>Magister Scientiae - MScThe growth of hydrogenated amorphous silicon carbide (a-SiC:H) thin films deposited by Hot- Wire Chemical Vapour Deposition (HWCVD) for solar cell applications has been studied. The films were characterized for structural properties using Fourier Transform Infrared Spectroscopy FTIR, Elastic Recoil Detection Analysis (ERDA), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Raman Spectroscopy (RS). A low temperature of the substrate heater maintained at 280 °C was used in this thesis due to the demand of low-cost solar cells based on cheap substrate that require deposition at such low temperatures. In this thesis, we showed that the structural properties of a-SiC:H films are dependent on the filament temperature and also on the CH4 gas flow rate. It was shown that in non-stoichiometric a-SiC:H, hydrogen content throughout the deposited films varies with depth. An attempt is done in this study to determine, for the first time the absorption strength of the C-Hn bonds in the 950 -1050 cm-1 band of the FTIR spectrum. Real-time ERDA was used to determine the hydrogen kinetics parameters in a single temperature ramp; a model based on the solution of the diffusion equation is used for this effect.
7
Gulses, Alkan Ali. "Ellipsometric And Uv-vis Transmittance Analysis Of Amorphous Silicon Carbide Thin Films." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605589/index.pdf.
Full textAbstract:
The fundamentals of the ellipsometry are reviewed in order to point out the strengths and weaknesses of the ellipsometric measurements. The effects of the surface conditions (such as degree of cleanliness, contaminated thin layer, roughness etc&hellip) on the ellipsometric variables are experimentally studied
the optimum procedures have been determined. Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) thin films are produced by plasma enhanced chemical vapor deposition (PECVD) technique with a circular reactor, in a way that RF power and carbon contents are taken as variables. These samples are analyzed using multiple angle of incidence ellipsometer and uv-vis spectrometer. These measurements have inhomogeneities in optical constants, such as thicknesses, refractive indices and optical energy gaps along the radial direction of the reactor electrode for different power and carbon contents.
8
Künle, Matthias [Verfasser]. "Silicon carbide single and multilayer thin films for photovoltaic applications / Matthias Künle." München : Verlag Dr. Hut, 2011. http://d-nb.info/1017353514/34.
Full text
9
Colston, Gerard B. "Wafer scale heteroepitaxy of silicon carbon and silicon carbide thin films and their material properties." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/103470/.
Full textAbstract:
For years now, many have believed the solution to reducing the cost of the wide bandgap compound semiconductor silicon carbide (SiC) is to grow its cubic form (3C-SiC) heteroepitaxially on silicon (Si). This has the potential to reduce cost, increase wafer size and integrate SiC with Si technology. After decades of research, 3C-SiC grown on Si is still yet to penetrate the commercial market as the process is plagued with various issues such as very high growth temperatures, thermal stresses, high cost, poor epitaxial material quality and poor scalability to wafer sizes beyond 100 mm diameter. The first section of this thesis starts with a focus on the traditional, high temperature growth of 3C-SiC carried out in the first industrial type SiC based reduced pressure chemical vapour deposition (RP-CVD) reactor installed in a UK University. After the process demonstrated little promise for mass scale implementation into the semiconductor industry, a radical change in strategy was made. The research pivoted away from SiC and instead focussed on silicon carbon alloys (Si1-yCy) with carbon (C) contents in the range of 1-3%. Si1-yCy has a range of applications in strain engineering and reducing contact resistance, differing from 3C- SiC quite significantly. Crystalline alloys with C contents around 1.5% were achieved using an industry standard Si based RP-CVD growth system. Analysis was carried out on the defects that form due to the saturation of C in higher content alloys. The high temperature annealing of Si1-yCy resulted in out diffusion of C and traces of 3C-SiC growth which presented itself as a potential buffer layer for 3C-SiC epitaxy. Through the careful selection of growth precursors and process optimisation, high crystalline quality 3C-SiC was grown heteroepitaxially on Si within the industry standard Si based RP-CVD and in-depth material characterisation has been carried out using a vast range of techniques. High levels of electrically active dopants were incorporated into the 3C-SiC and its electrical properties were investigated. Various investigations were carried out on suspended 3C-SiC and Si1-yCy films including strain and tilt measurements through micro X-ray diffraction and the effect of thickness and doping on their optical properties. The results led to a greater understanding of suspended films and provide a foundation for a number of applications in microelectromechanical systems (MEMS) and optical devices. Further material growth research was carried out on Si1-yCy multilayers, selective epitaxy of 3C-SiC and the growth of 3C-SiC on suspended growth platforms. Each topic presents an interesting area for further research. The research presented demonstrates new, state of the art 3C-SiC heteroepitaxial material and its basic structural, electrical and optical properties. A new low-cost and scalable process has been developed for the heteroepitaxial growth of 3C-SiC on Si substrates up to 100 mm with a clear path to scaling the technology up to 200 mm and beyond. Not only does the developed technology have a high commercial impact, it also paves the way for many interesting future research topics, some of which have been briefly investigated as part of this work.
10
Gold, Jeffrey Stephen. "Characterization of a novel methyl radical source and related thin film growth studies." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1787.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 108 p. : ill. (some col.) + appendix; 37 p. : ill. Includes abstract. Includes bibliographical references (p. 103-108; p. A-37).
11
Shelberg, Daniel Thomas. "PHYSICAL AND CHEMICAL PROPERTIES OF AMBIENT TEMPERATURE SPUTTERED SILICON CARBIDE FILMS." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1269963941.
Full textAbstract:
Thesis (Master of Sciences (Engineering))--Case Western Reserve University, 2010Department of Chemical Engineering Title from PDF (viewed on 2010-05-25) Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
12
Richards, Mark Rowse. "Process development for IrAl coated SiC-C functionally graded material for the oxidation protection of graphite /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10574.
Full text
13
Short, Eugene L. "Growth of oxide thin films on 4H- silicon carbide in an afterglow reactor." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001839.
Full text
14
Crocker, Janina. "Measurement of the Young's modulus of Hexoloy silicon carbide thin films using nanoindentation." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18414.
Full textAbstract:
Thin films of metals and ceramics are commonly used as the structural materials for microelectromechanical systems (MEMS). These systems are used for a wide range of applications that include sensors, displays, and portable power generators. Accurate measurement of the mechanical properties of these thin films is essential for the robust design of high-performance and reliable MEMS. In this thesis, the method of nanoindentation is used to characterize the elastic properties of thin films of Hexoloy-SG silicon carbide. This material is of particular interest for MEMS operating in harsh, hightemperature environments. Nanoindentation was performed using a commercial Hysitron TriboIndenter® equipped with a diamond Berkovich nanoindenter tip. During each nanoindentation test, the indenter was forced into the specimen by a calibrated load, while the indentation depth was recorded continuously with nanometer resolution. The first part of this thesis describes a detailed protocol for nanoindentation testing using the TriboIndenter® and discusses the calibration of the instrument using a quartz standard. The identification of errors due to drift, vibrations, and surface inhomogeneities is described in detail. This protocol was then used to test a 2.1 µm thick film of Hexoloy-SG silicon carbide film deposited on a 500 µm thick single-crystal silicon substrate. The film was tested with loads varying from 1,000 µN to 13,000 µN, such that the maximum indentation was always less than 10% of the film thickness. The nanoindentation load-displacement curves from a total of 155 individual indents were analyzed using three different methods to extract the value of the Young's modulus of the Hexoloy film. The first method, developed by Oliver and Pharr, is widely used in nanoindentation analysis, but does not account explicitly for the effects of the underlying substrate. It is valid strictly for monolithic materials. Therefore, refinements of the Oliver-Pharr method by King aDes structures formées de couches minces métalliques et céramiques sont couramment utilisées dans la conception de microsystèmes électromécaniques (MEMS). Ces derniers se retrouvent dans plusieurs domaines, tels que les capteurs, les vidéoprojecteurs et les systèmes de génération d'énergie portable. Pour concevoir des MEMS fiables, les propriétés mécaniques de ces couches minces doivent êtres connues précisément. Le but de cette thèse est d'utiliser la méthode de nanoindentation pour déterminer les propriétés mécaniques des couches minces de carbure de silicium Hexoloy-SG. Ce matériel à été développé pour des microsystèmes opérant dans des conditions thermiques et chimiques extrêmes. La nanoindentation a été réalisée par le système TriboIndenter® de Hysitron équipé d'une pointe Berkovich en diamant, de forme pyramidale à base triangulaire. Chaque indentation comprend un cycle charge/décharge durant lequel la pointe indentatrice est enfoncée et retirée du matériel par une force calibrée, tandis que la profondeur de l'indentation est surveillée continuellement au nanomètre près. La première partie de cette thèse décrit une procédure détaillée pour la nanoindentation avec le système TriboIndenter®, incluant la calibration de l'instrument utilisant une norme en quartz monolithique. Également, l'identification d'erreurs expérimentales reliées au système de nanoindentation dues à la dérive, aux vibrations et à la rugosité de l'échantillon et leurs mesures correctrices sont présentées. Par après, cette méthodologie a été utilisée pour tester les propriétés mécaniques d'une couche mince de Hexoloy-SG mesurant 2.1 µm d'épaisseur, déposée sur un substrat de silicium monocristallin comptant 500 µm d'épaisseur. La force exercée par l'indentateur sur l'échantillon varie de 1,000 µN à 11,000 µN, pour que la profondeur de l'indentation demeure en deçà de 10% de l'épaisseur totale de la co
15
Ahmed, Fatema. "Structural properties and optical modelling of SiC thin films." University of the Western Cape, 2020. http://hdl.handle.net/11394/7284.
Full textAbstract:
>Magister Scientiae - MScAmorphous silicon carbide (a-SiC) is a versatile material due to its interesting mechanical, chemical and optical properties that make it a candidate for application in solar cell technology. As a-SiC stoichiometry can be tuned over a large range, consequently is its bandgap. In this thesis, amorphous silicon carbide thin films for solar cells application have been deposited by means of the electron-beam physical vapour deposition (e-beam PVD) technique and have been isochronally annealed at varying temperatures. The structural and optical properties of the films have been investigated by Fourier transform Infrared and Raman spectroscopies, X-ray diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and UV-VIS-NIR spectroscopy. The effect of annealing is a gradual crystallization of the amorphous network of as-deposited silicon carbide films and consequently the microstructural and optical properties are altered. We showed that the microstructural changes of the as-deposited films depend on the annealing temperature. High temperature enhances the growth of Si and SiC nanocrystals in amorphous SiC matrix. Improved stoichiometry of SiC comes with high band gap of the material up to 2.53 eV which makes the films transparent to the visible radiation and thus they can be applied as window layer in solar cells.
16
Halindintwali, Sylvain. "A study of hydrogenated nanocrystalline silicon thin films deposited by hot-wire chemical vapour deposition (HWCVD)." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Full textAbstract:
In this thesis, intrinsic hydrogenated nanocrystalline silicon thin films for solar cells application have been deposited by means of the hot &ndashwire chemical vapour deposition (HWCVD) technique and have been characterised for their performance. It is noticed that
hydrogenated nanocrystalline silicon is similar in some aspects (mainly optical) to its counterpart amorphous silicon actually used as the intrinsic layer in the photovoltaic industry. Substantial differences between the two materials have been found however in their respective structural and electronic properties.
We show that hydrogenated nanocrystalline silicon retains good absorption coefficients known for amorphous silicon in the visible region. The order improvement and a reduced content of the bonded hydrogen in the films are linked to their good stability. We argue that provided a moderate hydrogen dilution ratio in the monosilane gas and efficient process pressure in the deposition chamber, intrinsic hydrogenated nanocrystalline silicon with photosensitivity better than 102 and most importantly resistant to the Staebler Wronski effect (SWE) can be produced.
This work explores the optical, structural and electronic properties of this promising material whose study &ndash
samples have been exclusively produced in the HWCVD reactors based in the Solar Cells laboratory of the Physics department at the University of the Western Cape.
17
Chiu, Chienchia. "Chemical vapor deposition of β-SiC thin films on Si(100) in a hot wall reactor." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/38661.
Full text
18
Tengdelius, Lina. "Growth and Characterization of ZrB2 Thin Films." Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-98308.
Full textAbstract:
In this thesis, growth of ZrB2 thin films by direct current magnetron sputtering is investigatedusing a high vacuum industrial scale deposition system and an ultra-high vacuum laboratory scalesystem. The films were grown from ZrB2 compound targets at temperatures ranging from ambient (without external heating) to 900 °C and with substrate biases from -20 to -120 V. Short deposition times of typically 100 or 300 s and high growth rates of 80-180 nm/min were emphasized to yield films with thicknesses of 300-400 nm. The films were characterized by thinfilm X-ray diffraction with the techniques θ/2θ and ω scans, pole figure measurements andreciprocal space mapping, scanning and transmission electron microscopy, elastic recoil detection analysis and four point probe measurements. The substrates applied were Si(100), Si(111),4H-SiC(0001) and GaN(0001) epilayers grown on 4H-SiC. The Si(111), 4H-SiC(0001) substrates and GaN(0001) epilayers were chosen given their small lattice mismatches to ZrB2 making them suitable for epitaxial growth.The films deposited in the industrial system were found to be close to stoichiometric with a low degree of contaminants, with O being the most abundant at a level of < 1 at.%. Furthermore, the structure of the films is temperature dependent as films deposited in this system without external heating are fiber textured with a 0001-orientation while the films deposited at 550 °C exhibitrandom orientation. In contrast, epitaxial growth was demonstrated in the laboratory scale system on etched 4H-SiC(0001) and Si(111) deposited at 900 °C following outgassing of the substrates at 300 °C and in-situ heat treatment at the applied growth temperature to remove the native oxides. However, films grown on GaN(0001) were found to be 0001 textured at the applied deposition conditions, which make further studies necessary to enable epitaxial growth on this substrate material. Four point probe measurements on the films deposited in the industrial system show typical resistivity values ranging from ˜95 to 200 μΩcm with a trend to lower values for the films deposited at higher temperatures and at higher substrate bias voltages.
19
Li, Xuebin. "Epitaxial graphene films on SiC : growth, characterization, and devices /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24670.
Full textAbstract:
Thesis (Ph.D.)--Physics, Georgia Institute of Technology, 2008.Committee Chair: de Heer, Walter; Committee Member: Chou, Mei-Yin; Committee Member: First, Phillip; Committee Member: Meindl, James; Committee Member: Orlando, Thomas
20
Sel, Kivanc. "The Effects Of Carbon Content On The Properties Of Plasma Deposited Amorphous Silicon Carbide Thin Films." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608292/index.pdf.
Full textAbstract:
The structure and the energy band gap of hydrogenated amorphous silicon carbide are theoretically revised. In the light of defect pool model, density of states distribution is investigated for various regions of mobility gap. The films are deposited by plasma enhanced chemical vapor deposition system with various gas concentrations at two different, lower (30 mW/cm2) and higher (90 mW/cm2), radio frequency power densities. The elemental composition of hydrogenated amorphous silicon carbide films and relative composition of existing bond types are analyzed by x-ray photoelectron spectroscopy measurements. The thicknesses, deposition rates, refractive indices and optical band gaps of the films are determined by ultraviolet visible transmittance measurements. Uniformity of the deposited films is analyzed along the radial direction of the bottom electrode of the plasma enhanced chemical vapor deposition reactor. The molecular vibration characteristics of the films are reviewed and analyzed by Fourier transform infrared spectroscopy measurements. Electrical characteristics of the films are analyzed by dc conductivity measurements. Conduction mechanisms, such as extended state, nearest neighbor and variable range hopping in tail states are revised. The hopping conductivities are analyzed by considering the density of states distribution in various regions of mobility gap. The experimentally measured activation energies for the films of high carbon content are too low to be interpreted as the difference between Fermi level and relevant band edge. This anomaly has been successfully removed by introducing hopping conduction across localized tail states of the relevant band. In other words, the second contribution lowers the mobility edge towards the Fermi level.
21
Shepperd, Kristin. "Low-energy electron induced processes in hydrocarbon films adsorbed on silicon surfaces." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29648.
Full textAbstract:
Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.Committee Chair: Orlando, Thomas; Committee Member: El-Sayed, Mostafa; Committee Member: First, Phillip; Committee Member: Lackey, Jack; Committee Member: Tolbert, Laren. Part of the SMARTech Electronic Thesis and Dissertation Collection.
22
Tumakha, Serhii. "Investigation of 4H and 6H-SIC thin films and schottky diodes using depth-dependent cathodoluminescence spectroscopy." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1138202968.
Full text
23
Torrance, David Britt. "Growth and electronic properties of nanostructured epitaxial graphene on silicon carbide." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50205.
Full textAbstract:
The two-dimensional phase of carbon known as graphene is actively being pursued as a primary material in future electronic devices. The goals of this thesis are to investigate the growth and electronic properties of epitaxial graphene on SiC, with a particular focus on nanostructured graphene. The first part of this thesis examines the kinetics of graphene growth on SiC(0001) and SiC(0001 ̅) by high-temperature sublimation of the substrate using a custom-built, ultra-high vacuum induction furnace. A first-principles kinetic theory of silicon sublimation and mass-transfer is developed to describe the functional dependence of the graphene growth rate on the furnace temperature and pressure. This theory can be used to calibrate other graphene growth furnaces which employ confinement controlled sublimation. The final chapter in this thesis involves a careful study of self-organized epitaxial graphene nanoribbons (GNRs) on SiC(0001). Scanning tunneling microscopy of the sidewall GNRs confirms that these self-organized nanostructures are susceptible to overgrowth onto nearby SiC terraces. Atomic-scale imaging of the overgrown sidewall GNRs detected local strained regions in the nanoribbon crystal lattice, with strain coefficients as high as 15%. Scanning tunneling spectroscopy (STS) of these strained regions demonstrate that the graphene electronic local density of states is strongly affected by distortions in the crystal lattice. Room temperature STS in regions with a large strain gradient found local energy gaps as high as 400 meV. Controllable, strain-induced quantum states in epitaxial graphene on SiC could be utilized in new electronic devices.Per request of the author and the advisor, and with the approval of the graduate office, the Acknowledgements page was replaced with an errata.
24
Vandersand, James Dennis. "Growth of 6H-SiC homoepitaxy on substrates off-cut between the [01-10] planes." Master's thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-11072002-095154.
Full text
25
Awad, Yousef Odeh. "Characterization of amorphous silicon carbide and silicon carbonitride thin films synthesized by polymer-source chemical vapor deposition mechanical structural and metal-interface properties." Thèse, Université de Sherbrooke, 2006. http://savoirs.usherbrooke.ca/handle/11143/1821.
Full textAbstract:
Amorphous silicon carbide (a-SiC) and silicon carbonitride thin films have been deposited onto a variety of substrates by Polymer-Source Chemical Vapor Deposition (PS-CVD). The interfacial interaction between the a-SiC films and several substrates including silicon, SiO[subscript 2], Si[subscript 3]N[subscript 4], Cr, Ti and refractory metal-coated silicon has been studied. The effect of thermal annealing on the structural and mechanical properties of the prepared films has been discussed in detail. The composition and bonding states are uniquely characterized with respect to the nitrogen atomic percentage introduced into the a-SiCN:H films. Capacitance-voltage (C-V) measurements were systematically used to evaluate the impurity level of the deposited a-SiC films. The chemical bonding of the films was systematically examined by means of Fourier transform infrared spectroscopy (FTIR). In addition, elastic recoil detection (ERD) and X-ray photoelectron spectroscopy (XPS) techniques were used to determine the elemental composition of the films and of their interface with substrates, while X-ray reflectivity measurements (XRR) were used to account for the film density. Spectral deconvolution was used to extract the individual components of the FTIR and XPS spectra. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also employed to characterize the surface morphology of the films. In addition, their mechanical properties [(hardness (H) and Young's modulus (E)] were investigated by using the nanoindentation technique. The impurity levels of the a-SiC films were found to be clearly correlated with the nature of the underlying substrates. The Pt-Rh and TiN-coated Si substrates were shown to lead to the lowest impurity level (~ 1×10[superscript 13] cm[superscript -3]) in the PS-CVD grown a-SiC films, while Cr and Ti-coated Si substrates induced much higher impurity concentrations. Such high impurity levels were shown to be a consequence of a strong metallic diffusion of the metallic species (Cr or Ti). In contrast, no diffusion was observed at the interface of a-SiC with either Pt-Rh or TiN. Our results pinpointed TiN-coated Si as the electrode material of choice that satisfied best all criteria required for the integration of a-SiC into opto-electronic devices. FTIR measurements revealed that not only the intensity of a-SiC absorption band linearly increased, but also its position is found to shift to a higher wave number as a result of annealing. In addition, the bond density of Si-C is found to increase from (101.6-224.5)×10[superscript 21] bond[dot]cm[superscript -3] accompanied by a decrease of Si-H bond density from (2.58-0.46)× 10[superscript 21] bond[dot]cm[superscript -3] as a result of increasing the annealing temperature (T[subscript a]) from 750 to 1200 [degrees]C. Annealing-induced film densification is confirmed by the XRR measurements, as the a-SiC film density is found to increase from 2.36 to ~ 2.75 g/cm[superscript -3] when T[subscript a] is raised from 750 to 1200 [degrees]C. In addition, as annealing temperature T[subscript a] is increased from 750 to 1200 [degrees]C, both hardness and Young's modulus are found to increase from 15.5 to 17.6 GPa and 155 to 178 GPa, respectively. On the microstructural level, the increase incorporation of N in the a-SiCN:H films is found not only to lead to C atoms substitution by N atoms in the local Si-C-N environment but also to the formation of a complex structure between Si, C and N. For instance, the FTIR spectra show a remarkable drop in the intensity of Si-C vibration accompanied by the formation of further bonds including Si-N, C-N, C=N, C[identical to]N and N-H with increasing NH[subscript 3]/Ar ratio. Moreover, the XPS spectra showed the existence of different chemical bonds in the a-SiCN:H films such as Si-C, Si-N, C-N, C=N and C=C. Both FTIR and XPS data demonstrate that the chemical bonding in the amorphous matrix is more complicated than a collection of single Si-C, Si-N, or Si-H bonds. Furthermore, the increase incorporation of N in the a-SiCN:H films resulted in an increase of the average R[subcsript rms] surface roughness from 4 to 12 nm. Moreover, the films became porous with pore size and density increase as a result of increasing N at.%. Ultimately, both H and E of the a-SiCN:H films were found to be sensitive to their N content, as they decreased (from ~17 GPa and 160 GPa to ~13 GPa and 136 GPa, respectively) when the N content was increased from 0 to 27 at.%. The formation of Si-N, Si-H, and N-H bonds at the detriment of the more stiffer Si-C bonds are thought to account for the observed lowering of the mechanical properties of the a-SiCN:H films such as their N content increased. Our results confirmed the previously-established constant-plus-linear correlation between the mechanical properties of the a-SiC films and their bond densities.
26
Chakravarthy, Pramod. "Silicon carbide coatings by plasma-enhanced chemical vapor deposition on silicon and polyimide substrates." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179519920.
Full text
27
Iqbal, Abid. "The Sputtering and Characterization of C-Axis Oriented Aluminium Nitride Thin Films On Top Of Cubic Silicon Carbide-On-Silicon Substrates for Piezoelectric Applications." Thesis, Griffith University, 2017. http://hdl.handle.net/10072/365840.
Full textAbstract:
The growth of micro-scale wireless electronics is increasing significantly because of their miniaturisation and low power consumption. These devices currently draw power from batteries or chemical fuel cells. Their limited life-spans prompt active research to find an alternative solution by harvesting ambient energy from the environment. Numerous sources are available such as solar, thermoelectric, acoustic, and mechanical vibrations. Among them, mechanical vibration is perhaps the most practical to power these wireless electronic devices via piezoelectric transduction. Three most common piezoelectric materials are Lead zirconate titanate (PZT), zinc oxide (ZnO) and aluminum nitride (AlN). AlN is preferred over ZnO and PZT for several reasons. Chiefly among them is because it has the highest electromechanical coupling along the c-axis of wurzite AlN for longitudinal deformation. This thesis investigates the sputtering of c-axis oriented AlN on top of cubic-silicon carbide-on-silicon (3C-SiC-on-Si) substrates for piezoelectric applications. The 3C-SiC buffer layer was used to reduce the lattice mismatch and thermal expansion coefficient between AlN and Si. In the first part of the research, RF sputtering was utilised for depositing AlN. The low growth rate of RF sputtering prompted the switch to DC sputtering. The DC sputtering suffered from electrical arching problems, which were addressed by gradually decreasing the sputtering pressure. However, the system had the limitation of 1200 W of maximum power.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
28
Sánchez, Sovero Luis Francisco. "Effect of thermal annealing treatments on the optical and electrical properties of aluminum-doped, amorphous, hydrogenated silicon carbide thin films." Master's thesis, Pontificia Universidad Católica del Perú, 2019. http://hdl.handle.net/20.500.12404/14529.
Full textAbstract:
In this work, a systematic study of the structural, optical and electrical properties of aluminum doped hydrogenated amorphous silicon carbide (Al-doped a-SiC:H) thin films grown by radio frequency magnetron sputtering is presented. The samples were grown using a high purity Al and SiC targets in a hydrogen-rich atmosphere and then were subjected to a rapid thermal annealing processes with temperatures of up to 600 °C. The film thickness ranged from 321 nm to 266 nm. The amorphous nature of the thin films was confirmed by X-ray diffraction measurements before and after the annealing treatments. Fourier transform infrared spectroscopy analysis revealed the different heteronuclear bonds present in the samples, whilst Raman spectroscopy showed the different homonuclear bonds present in the material. The evolution of the latter bonds with annealing temperature was assessed, showing a change in the structure of the thin film. Energy-dispersive X-Rays Spectroscopy confirmed the incorporation of aluminum in the amorphous silicon carbide matrix. UV-VIS Transmittance spectra revealed optical parameters such as Tauc energy bandgap, Iso-absorption energy bandgap and refractive index. Furthermore, the bandgap is also determined by means of a recently developed band-fluctuation model. In addition, electrical resistivity is determined by means of a four-probe Van Der Pauw method. Only the samples annealed at 600 °C exhibited contacts with an Ohmic behavior. The annealed films exhibited lower resistivities than the as-deposited ones, probably due to a thermal-induced reordering of the atoms. This reordering is shown in the variation of the Urbach energy which is related to an increase in the Si-C bond density, due to the dissociation of the hydrogen-related bonds.En este trabajo de tesis se presenta el estudio las propiedades estructurales y optoelectrónicas de carburo de silicio amorfo hidrogenado dopado con aluminio fabricado mediante pulverización catódica de radio frecuencia. Las muestras se fabricaron usando target de SiC y Al de alta pureza en atmosfera de hidrogeno. Luego las películas fueron calentadas hasta la temperatura de 600°C en un horno de rápido procesamiento térmico. La difracción de rayos X confirma la naturaleza amorfa de las películas. Los espectros de absorción infrarroja muestran los diferentes enlaces hetero-nucleares mientras que la espectroscopia Raman nos muestra los diferentes enlaces hononucleares presentes en la muestra. Se evaluó la evolución de los últimos enlaces con el tratamiento térmico, mostrando un cambio en la estructura del material. Espectroscopía de dispersión de energía de rayos X nos muestra la incorporación de aluminio en la matriz de carburo de silicio amorfo. Los espectros de transmitancia UV-VIS revelan parámetros ópticos tales como energía de Tauc, energía de Iso- absorción, energía de Tauc e índice de refracción. Además, el modelo de fluctuación de bandas desarrollado recientemente nos permite determinar los bordes de movilidad y energía de Urbach. Adicionalmente, el método de Van Der Pauw nos permite determinar el valor de la resistividad eléctrica de la muestra, solo a 600°C, donde se obtuvo un comportamiento óhmico mostrando baja resistividad eléctrica, probablemente debido a un reordenamiento de los átomos inducidos térmicamente. Este reordenamiento estructural se muestra en la variación de la energía de Urbach que está asociada con el aumento de la densidad de enlaces Si-C, debido a la disociación de los enlaces relacionados con el hidrogeno.
Tesis
29
Rawlinson, Patrick Theodore. "The Mechanical Properties of Submicron-Thick, Large-Area 3C-SiC Diaphragms." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1328296558.
Full text
30
Short, Eugene L. III. "Sequential Afterglow Processing and Non-Contact Corona-Kelvin Metrology of 4H-SiC." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/19.
Full textAbstract:
Silicon carbide (SiC) is a wide band-gap semiconductor with advantageous electrical and thermal properties making it attractive for high temperature and power applications. However, difficulties with oxide/SiC structures have posed challenges to the development of practical MOS-type devices. Surface conditioning and oxidation of 4H-SiC were investigated using a novel sequential afterglow processing approach combined with the unique capabilities of non-contact corona-Kelvin metrology. The use of remote plasma assisted thermal oxidation facilitated film growth at low temperature and pressure with the flexibility of sequential in-situ processing options including pre-oxidation surface conditioning. Corona-Kelvin metrology (C-KM) provided a fast, non-destructive method for electrical evaluation of oxide films and semiconductor surfaces. Non-contact C-KM oxide capacitance-voltage characteristics combined with direct measurement of SiC surfaces using C-KM depletion surface barrier monitoring and XPS analysis of surface chemistry were interpreted relating the impact of afterglow conditioning on the surface and its influence on subsequent oxide thin film growth. Afterglow oxide films of thicknesses 50-500 angstroms were fabricated on SiC epi-layers at low growth temperatures in the range 600-850°C, an achievement not possible using conventional atmospheric oxidation techniques. The inclusion of pre-oxidation surface conditioning in forming gas (N2:H2)* afterglow was found to produce an increase in oxide growth rate (10-25%) and a significant improvement in oxide film thickness uniformity. Analysis of depletion voltage transients on conditioned SiC surfaces revealed the highest degree of surface passivation, uniformity, and elimination of sources of charge compensation accomplished by the (N2:H2)* afterglow treatment for 20 min. at 600-700°C compared to other conditioning variations. The state of surface passivation was determined to be very stable and resilient when exposed to a variety of temporal, electrical, and thermal stresses. Surface chemistry analysis by XPS gave evidence of nitrogen incorporation and a reduction of the C/Si ratio achieved by the (N2:H2)* afterglow surface treatment, which was tied to the improvements in passivation, uniformity, and growth rate observed by non-contact C-KM measurements. Collective results were used to suggest a clean, uniform, passivated, Si-enriched surface created by afterglow conditioning of 4H-SiC as a sequential preparation step for subsequent oxidation or dielectric formation processing.
31
Bossard, Maxime. "Développement de moules intrinsèquement antiadhésifs pour l'étude du collage en nano-impression." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT010/document.
Full textAbstract:
La nano-impression est une technique de lithographie qui consiste à reproduire les motifs contenus dans un moule, par pressage de celui-ci sur un film de résine. Cette technologie – rapide et peu coûteuse à mettre en oeuvre – est prometteuse mais son utilisation à l’échelle industrielle nécessite encore des améliorations notamment en termes de limitation de la défectivité des motifs reproduits. Des solutions existent pour pallier cette limitation, à travers notamment l’utilisation de traitements antiadhésifs qui se greffent en surface des moules et permettent de favoriser les étapes de démoulage. Cependant, ces traitements de moules ont une durée de vie limitée, ce qui limite la rentabilité globale du procédé de nano-impression.Ce projet de thèse s’intéresse à la question de la durabilité des moules et propose des matériaux alternatifs pour la fabrication de moules de nano-impression.Pour répondre aux exigences des acteurs de la nano-impressions, quatre matériaux (le Diamond-like carbon, le carbure de silicium et leurs versions dopées en fluor) ont été développés pour une utilisation en tant que matériaux de moules alternatifs au silicium et au quartz. La caractérisation des propriétés physiques et physico-chimiques a été réalisée de sorte à sélectionner les matériaux les plus prometteurs qui ont ensuite été structurés pour une utilisation en tant que moules fonctionnels.Les propriétés d’adhérence de ces matériaux ont ensuite été caractérisées tant en nano-impression assistée par ultraviolets qu’en nano-impression thermique. Ces essais ont permis de montrer que les matériaux développés, malgré une grande énergie de surface, présentent intrinsèquement un caractère antiadhésif lié à leur inertie chimiqueNanoimprint is a lithography technology which consists in structuring a polymer film by pressing a structured mold into it. This promising method is low-cost and has a high throughput, but its implementation in industry still requires improvements, particularly regarding the defectivity of imprinted structures. To circumvent this defectivity, the use of antiadhesive treatments, grafted to the mold surface has been developed to facilitate the demolding step. However, these treatments have a limited lifespan, thereby empeding the global nanoimprint cost-effectiveness.This thesis focuses on mold durability and suggests alternative materials for the fabrication of nanoimprint molds.To match nanoimprint requirements, four materials (Diamond-like carbon, Silicon carbide and their fluorine-doped versions) were developed to be used as alternatives to silicon and quartz. Physical and physico-chemical characterization were carried out, so as to determine the best candidates that were then patterned, leading to usable molds.Adhesion properties of these materials were then characterized both in UV-nanoimprint and thermal-nanoimprint procedures. These investigations showed that despite their high surface energies, the developed materials exhibit intrinsically antiadhesive properties, thanks to their chemical inertness
32
Lau, S. P. "Thin film silicon carbide for electroluminescent devices." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637853.
Full textAbstract:
In this research, the optoelectronic and structural properties of thin film silicon carbide (SiC) prepared by plasma enhanced chemical vapour deposition and excimer (ArF) laser crystallisation are presented. These materials have been utilised as p-i-n electroluminescent devices, including development of various novel device structures. A wide-ranging series of experiments aimed at optimising the deposition conditions of amorphous and microcrystalline SiC films are described. Dark conductivity, photoconductivity, photoluminescence, optical absorption by Swanepoel's method and constant photocurrent method (CPM), scanning and transmission electron microscopy, infrared spectroscopy, and elastic recoil detection analysis were employed to characterise the films. Absorption spectra and the density of states profile of amorphous silicon carbide as found by CPM are reported. As the carbon content increases, the valence band tail becomes broader. At the same time, the deep defect density of states increases and also becomes broader. The CPM data also verified that the band gap widening is due to the conduction band shifting with increasing carbon content. It is shown that H2 dilution leads to an improvement of electronic properties via a decrease in the density of localised states. A novel method has been developed to prepare highly conductive and wide band gap doped microcrystalline silicon carbide (μc-SiC) by excimer (ArF) laser crystallisation. After crystallisation, this material has Tauc gap of around 2.0 eV and exhibits a dark conductivity as high as 20 (Ωcm)-1, more than ten orders of magnitude higher than before the laser irradiation. This is shown to be mainly correlated to structural change. The dopant concentration plays a dominant role in the electrical transport properties of μc-SiC, regardless of type of dopant and carbon concentration up to 30 at.%. Laser crystallised μc-SiC can be utilised not only as the carrier injection layer in a-SiC:H based electroluminescent devices, but also as a luminescent layer. EL devices fabricated with μc-SiC as a hole injector possess the highest electroluminescent intensity, the most stable emission and the longest operating life-time among all the investigated device structures. The electroluminescence from these devices is possibly related to the formation of some form of porous SiC by laser crystallisation.
33
Wang, Feng. "Surface/interface modification and characterization of C-face epitaxial graphene." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53855.
Full textAbstract:
Graphene has been one of the most interesting and widely investigated materials in the past decade. Because of its high mobility, high current density, inherent strength, high temperature stability and other properties, scientists consider it a promising material candidate for the future all-carbon electronics. However, graphene still exhibits a number of problems such as an unknown interface structure and no sizable band gap. Therefore, the purpose of this thesis is to probe and solve these problems to make graphene suitable for electronics. The work focuses on high-quality C-face epitaxial graphene, which is grown on the (000-1) face (C-face) of hexagonal silicon carbide using the confinement-controlled sublimation method. C-face epitaxial graphene has much higher mobility compared to Si-face graphene, resulting from its special stacking order and interface structure, the latter of which is not fully understood. Thus, the first part of the work consists of a project, which is to investigate and modify the interface and the surface of C-face graphene by silicon deposition and annealing. Results of this project show that silicon can intercalate into the graphene-SiC interface and form SiC by bonding carbon atoms on the graphene surface. Another crucial problem of graphene is the absence of a band gap, which prevents graphene from becoming an ideal candidate for traditional digital logic devices. Therefore, the second project of this work is devoted to introducing a wide band gap into the graphene electronic structure by growing from a nitrogen-seeded SiC. After successful opening of a band gap, a pre-patterning method is applied to improve graphene thickness variations, orientational epitaxy, and the gapped electronic structure.
34
Schillinger, Kai [Verfasser], and Harald [Akademischer Betreuer] Hillebrecht. "Crystalline silicon carbide intermediate layers for silicon thin-film solar cells = Kristalline Siliciumkarbid Zwischenschichten für Silicium Dünnschicht Solarzellen." Freiburg : Universität, 2014. http://d-nb.info/1123480354/34.
Full text
35
Barnes, Andrew Charles. "Characterization of High-Aspect Ratio, Thin Film Silicon Carbide Diaphragms Using Multimode, Resonance Frequency Analysis." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1414844482.
Full text
36
Abou, Hamad Valdemar. "Elaboration et caractérisation de contacts électriques à base de phases MAX sur SiC pour l'électronique haute température." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI079.
Full textAbstract:
Les applications de puissance dans lesquelles la température ambiante est élevée, provoquent l’augmentation de la température dans les dispositifs électroniques. De ce fait, il est important de développer les dispositifs électroniques pour pouvoir supporter des densités de courant et de puissance plus élevées. Dans cette thèse, nous avons pour objectif de jeter les bases d’une technologie en totale rupture avec celles existantes pour la fabrication d’une nouvelle génération de contacts électriques à base de Ti3SiC2, stables, fiables et reproductibles sur le Carbure de Silicium pour les applications à très hautes températures (300 – 600ºC). Deux méthodes d’élaborations seront étudiées, dans cette thèse, pour synthétiser le Ti3SiC2. La première est par voie réactionnelle, et la deuxième approche consistera à utiliser la technique Pulsed Laser Deposition (PLD), en utilisant une cible de Ti3SiC2. Le but est de développer des contacts ohmiques de bonne qualité. Des caractérisations physico-chimiques, électriques (TLM) et mécaniques (W-H et RSM) ont été effectuées sur les contacts de Ti3SiC2. Ces échantillons ont subi un vieillissement, à 600ºc pendant 1500h sous Argon, dans le but d’étudier la stabilité et la fiabilité des contacts électriques aux hautes températures. Les résultats des caractérisations ont montré que la fiabilité et la stabilité chimique entre Ti3SiC2 et SiC ont permis aux contacts de garder le comportement ohmique avec une faible résistivité électrique et un bon comportement mécanique, même après 1500h de vieillissement. De plus, les simulations réalisées ont servi à déterminer l’effet des ITR sur la dissipation de la chaleur et sur les contraintes mécaniques exercées sur une diode PN haute puissance. Dans cette thèse, nous avons montré qu’un contact ohmique, à base de Ti3SiC2, peut rester stable et fiable sur un substrat 4H-SiC, dans des températures allant jusqu’à 600ºCPower applications in which the ambient temperature is high, cause the increase of temperature in electronic components. Therefore, it is important to develop electronic devices that are able to withstand high current and high-power densities. In this thesis, our objective is to lay the foundations of a new technology for the manufacture of a new generation of Ti3SiC2 MAX phase-based electrical contacts, stable, reliable and reproducible on Silicon Carbide for very high temperature applications (300 - 600ºC). To synthesize Ti3SiC2 on SiC, two elaboration methods were studied in this thesis. The first approach is a reaction method, and the second approach consists on using a Ti3SiC2 target via the Pulsed Laser Deposition (PLD) technique. Our goal is to develop a good quality ohmic contacts. Physico-chemical, electrical (TLM) and mechanical (W-H and RSM) characterizations were performed on the Ti3SiC2 contacts. These samples underwent a thermal aging test at 600°C for 1500 hours under Argon, in order to study the stability and reliability of the electrical contacts at high temperatures. The obtained results showed that the reliability and the chemical stability between Ti3SiC2 and SiC allowed the contacts to keep an ohmic behavior with low electrical resistivity, in addition to a good mechanical behavior, even after 1500 hours of aging at 600ºC. Furthermore, the thermomechanical simulations performed were used to determine the effects of Interfacial Thermal Resistances on the heat dissipation and the mechanical stresses exerted on a high power PN diode. In this thesis, we have shown that an ohmic contact, based on Ti3SiC2, can remain stable and reliable on a 4H-SiC substrate, in temperatures up to 600ºC
37
Karnick, David A. "Miniaturization of Folded Slot Antennas through Inductive Loading and Thin Film Packaging." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1295549545.
Full text
38
Parikh, Rinku Pankaj. "Simulation-based design, optimization, and control of silicon carbide and gallium nitride thin film chemical vapor deposition reactor systems." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3976.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Chemical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
39
Sobola, Dinara. "Nedestruktivní lokální diagnostika optoelektronických součástek." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-233678.
Full textAbstract:
Chceme-li využít nové materiály pro nová optoelektronická zařízení, potřebujeme hlouběji nahlédnout do jejich struktury. K tomu, abychom toho dosáhli, je však nutný vývoj a aplikace přesnějších diagnostických metod. Předložená disertační práce, jako můj příspěvek k částečnému dosažení tohoto cíle, se zabývá metodami lokální diagnostiky povrchu optoelektronických zařízení a jejich materiálů, většinou za využití nedestruktivních mechanických, elektrických a optických technik. Tyto techniky umožňují jednak pochopit podstatu a jednak zlepšit celkovou účinnost a spolehlivost optoelektronických struktur, které jsou obecně degradovány přítomností malých defektů, na nichž dochází k absorpci světla, vnitřnímu odrazu a dalším ztrátovým mechanismům. Hlavní úsilí disertační práce je zaměřeno na studium degradačních jevů, které jsou nejčastěji způsobeny celkovým i lokálním ohřevem, což vede ke zvýšené difúze iontů a vakancí v daných materiálech. Z množství optoelektronických zařízení, jsem zvolila dva reprezentaty: a) křemíkové solární články – součástky s velkým pn přechodem a b) tenké vrstvy – substráty pro mikro optoelektronická zařízení. V obou případech jsem provedla jejich detailní povrchovou charakterizaci. U solárních článků jsem použila sondovou mikroskopii jako hlavní nástroj pro nedestruktivní charakterizaci povrchových vlastností. Tyto metody jsou v práci popsány, a jejich pozitivní i negativní aspekty jsou vysvětleny na základě rešerše literatury a našich vlastních experimentů. Je také uvedeno stanovisko k použití sondy mikroskopických aplikací pro studium solárních článků. V případě tenkých vrstev jsem zvolila dva, z hlediska stability, zajímavé materiály, které jsou vhodnými kandidáty pro přípravu heterostruktury: safír a karbid křemíku. Ze získaných dat a analýzy obrazu jsem našla korelaci mezi povrchovými parametry a podmínkami růstu heterostruktur studovaných pro optoelektronické aplikace. Práce zdůvodňuje používání těchto perspektivních materiálů pro zlepšení účinnosti, stability a spolehlivosti optoelektronických zařízení.
40
Hsu, Jen-Shiou, and 徐振修. "Growth of Silicon Carbide Thin Films from Hexamethyldisilane." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/29987415979333450168.
Full text
41
Lin, Wen-Chieh, and 林文傑. "Porous Silicon Carbide Thin Films on Silicon Substratesfor High Temperature Photodetecting Application." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/97551407684721079954.
Full text
42
Lertwiwattrakul, Wimol. "Fabrication of ultrathin SiC film using grafted poly(methylsilane)." Thesis, 2000. http://hdl.handle.net/1957/33083.
Full textAbstract:
��-SiC is a semiconductor for high temperature devices, which exhibits several outstanding properties such as high thermal stability, good chemical stability and wide band gap. There is a possibility of fabricating a crack-free ultrathin SiC film on silicon wafers by pyrolysis of polymethylsilane (PMS) film.
This study looks into the possibility, as the first phase, to modify the surface of silicon and graft PMS onto the surface. A new technique reported in this thesis consists of a surface modification with trimethoxysilylpropene (TSP) followed by the surface attachment of dichloromethylsilane (DMS) in the presence of a platinum catalyst, which acts as the first unit for grafting PMS molecules by the sodium polycondensation of additional DMS monomers. The grafted PMS polymers would serve as the pyrolytic precursor to be converted into thin layers of SiC.
Surface analysis of these films on silicon wafers by X-ray photoelectron spectroscopy (XPS) indicated that the silicon surface was successfully modified with TSP, attached with DMS, and finally grafted with PMS. It was also confirmed by
powder X-ray diffraction (XRD) that PMS formed simultaneously in the bulk solution was converted into SiC by pyrolysis at temperatures above 1100��C under Ar atmosphere.
Extended studies showed that the PMS-derived coatings, formed in an Ar stream containing 1% H��� at 400��C, were significantly oxidized, and further heating to 700��C yielded a Si0��� layer with graphitic carbon. The intensity of the graphite peak decreased with an increase in the pyrolysis temperature. Based on these preliminary studies towards the second phase, i.e. the pyrolysis of PMS to SiC, the need for further research to eliminate the oxidation source(s) is strongly suggested.Graduation date: 2001
43
LI, SHU-FEN, and 李淑芬. "Low pressure chemical vapor deposition of silicon carbide thin films from dodecamethylcyclohexasilane." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/78532155471821490694.
Full text
44
Chang-Tai, Sung, and 宋長泰. "Study of Silicon Carbide Thin Films from Polycarbosilane Acting as Buffer Layers for Diamond Film Growth." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/02420885976030101675.
Full textAbstract:
碩士國立臺灣科技大學
材料科技研究所
92
Polycarbosilane(PCS) was dissolved in toluene at various concentration levels and the resulting solutions were spun-coated onto <100>silicon wafers. The films were heat-treated under vacuum at temperatures in the range between 900℃ and 1150℃,and held for different times to from silicon carbide (SiC). The resulting SiC films were characterized using Fourier transform infrared spectrophotometer(FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The SiC films were used as buffer layers for diamond film growth. The diamond films were grown by hot filament chemical vapor deposition (HFCVD). In this study the effects of the growth pressure and subtract temperature on the morphology of diamond films were discussed. The structure of the diamond film was characterized by SEM , and XRD. The nucleation density of diamond on silicon was very low(6.2×106/cm2), but the nucleation density of diamond on SiC buffer layer was enhanced to 1.2×1011/cm2.The effect of enhancement of diamond nucleation may provide a solution for selective growth of diamond film.
45
Hu, Li-Wen, and 胡力文. "Growth of silicon carbide thin films from 1,2-dimethyldisilane by low temperature chemical vapor deposition." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/43683318001581858821.
Full textAbstract:
碩士國立交通大學
應用化學研究所
85
1,2-Dimethyldisilane was used as a single precursor to deposit siliconcarbide thin films by low pressure chemical vapor deposition. The filmswere deposited under two different conditions which were thermal activation only and with Ar as the carrier gases. Using this precursor, thelowest possible temperature to grow silicon carbide films was achieved at773 K. The thin films were characterized by XRD, SEM, FT-IR andESCA,AES. Decomposition of CH3SiH2SiH2CH3 into intermediatesCH3SiH (methylsilyene) and CH3SiH3(methylsilane) is proposed for thisreaction to rationalize this low temperature process
46
Van, Heerden Johannes Lodewikus. "Materiaaleienskappe van amorfe silikonkarbied dun lagies." Thesis, 2014. http://hdl.handle.net/10210/13094.
Full text
47
Chen, Yih-Wen, and 陳奕文. "Growth of Silicon Carbide Thin Films from Tris(trimethylsilyl) silane by Low Pressure Chemical Vapor Deposition." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/79073003574729002996.
Full textAbstract:
碩士國立交通大學
應用化學系
82
Tris(trimethylsilyl)methylsilane was used as a single sou- cursor for depositing beta-SiC thin films low pressure chemical vapor deposition. Deposition of uniform on Si (111) substrate was carried out at temperatures 873-1473 K in a re-asma- enhanced hot-wall reactor.Morphology of the films there was altered by deposition temperature and the precursorization temperature.Their crystallinity could be improvedgen plasma was used to assist deposition.The results indicated that when deposition between 1073K and 1473K,there were two kinds of growth mechanisms.Below 1273K the reactionsurface reaction controlled and the energy of acti- vation was 28.8kcal/mol, above 1273K the process was diffusion controlled.When hydrogen plasma was used to assist the depo- sition,the energy of activation was 22.8kcal/mol.Carbon andn distributions are oniform in the films. Elementalwas characterized to be C/ Si=1.1-1.8.In general the Si/C ratios of the films were close to 1 at high temper-of deposition.
48
Chen, Yi-Wen, and 陳奕文. "Growth of Silicon Carbide Thin Films from Tris(trimethylsilyl) silane by Low Pressure Chemical Vapor Deposition." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/01602784900504230147.
Full text
49
Chiu, Shih-Hsuan, and 邱世璿. "Fabrication of Silicon Carbide Thin Films Using Hot-Wire CVD for Solar-Cell Intrinsic Layer Applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/31541904960815976314.
Full textAbstract:
碩士國立中興大學
材料科學與工程學系所
98
In this thesis, silicon carbide (SiC) thin films prepared by hot-wire chemical vapor deposition (HWCVD) system was investigated for absorption layer of thin-film solar cells applications. During the deposition, the gas flow rate ratios of SiH4 and CH4 and H2 dilution were varied to study the effects of process conditions on the optoelectronic characteristics and microstructures of SiC thin films. The optimized process conditions of SiC thin film deposition were used to fabricate thin film solar cells. Details of material characteristics of SiC thin films were investigated in terms of x-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectrometer, x-ray diffraction (XRD), Raman spectroscopy, and field-emission scanning electron microscopy (FESEM). Electrical properties of SiC thin films were determined by I-V measurement under AM1.5. The optimum deposition conditions of SiC thin film were SiH4/CH4 ratio of 1 and without H2 dilution. The optical bandgap and ratio of photo- and dark-conductivity of SiC thin film were 1.98 eV and 1000, respectively. In thin film solar cell fabrication, p-type SiC, intrinsic SiC, and n-type microcrystalline Si thin films were prepared on ITO glass substrates by HWCVD system. Al back-electrode was used and prepared by electron-beam evaporation. The efficiency of SiC thin film solar cells was 2.44 %. The further improvement of process conditions on SiC thin film could be performed for tandem solar cells.
50
Dreyer, Aletta Roletta Elizabeth. "Homogeniteit en stabiliteit van amorfe silikon dun lagies." Thesis, 2014. http://hdl.handle.net/10210/9682.
Full textAbstract:
M.Sc. (Physics)Amorhous silicon is one of the most promising materials for large area solar cells for terestrial photovoltaic applications. Unfortunately these cells suffer from two serious problems: the efficiencies drop when laboratory processes are scaled up and the cells degrade after some exposure to sunlight. The exact causes of these two problems are still unknown. In this project some aspects of the above two problems where investigated. The drop in efficiency due to scaling up of laboratory processes can be ascribed to macroscopic inhomogeneities in the film. An investigation was done by changing the chamber geometry and gas flow pattern to establish empirical conditions to obtain films with maximum macroscopic homogeneity. It was found that a uniform electric field above the substrate was the most important factor determining the macroscopic homogeneity of the film. The hydronamic gas flow pattern was of secondary importance. Some techniques to obtain a uniform electric field has been devised. The photo-degradation was investigated by illuminating films of o-Si.H with simulated sunlight for different lenghts of time. The change in the electrical and optical properties of the intrinsic films were determined as function of total photon flux. No change in the optical properties could be detected. The effect of the photo-degradation manifests itself in a drop in the the dark conductivity and photoconductivity. The observed phenomena is explained in terms of photo-induced deep levels in the gap. The Fermi level shifts to the middle of the gap due to these defect states, causing a drop in the free carrier concentration and conductivity. These defect levels increase the absorptiom coefficient in the long wavelength region, but they also decrease the lifetime of the photo-generated carriers. The photo-induced defects were investigated with the CPM-technique. A large part of this project involved the construction and commissioning of the CPM-apparatus. It was found that the light introduced two types of defects at energies 0.5 eV and 0.75 eV below the conduction band edge. The concentration of the defects increases with illumination, but saturates after about 24 hours of illumination. The defects could almost completely be annealed at ISOaC. The photo-degradation of o-Si.H solar cells is ascribed to the reduction in the carrier lifetimes of photo-generated carriers due to recombination at these defect centers.