Dissertations / Theses: 'SiC thin film'

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Ma, Yunfei. "Micromagentic [sic] study of magnetoeleastic materials /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/7068.

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Wang, Feng. "Surface/interface modification and characterization of C-face epitaxial graphene." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53855.

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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.

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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.

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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

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Saifaddin, Burhan Khalid. "Development of Deep Ultraviolet (UV-C) Thin-Film Light-Emitting Diodes Grown on SiC." Thesis, University of California, Santa Barbara, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10975858.

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UV-C LEDs in the range of 265–280 nm are needed to develop new disinfection and biotechnology applications. The market share for UV-C LED, versus UV-C lamps (Hg discharge and Xe), increased from 8% in 2008 ($240M) to 25% in 2018 ($810M). However, while low-pressure mercury lamps are ~30% energy efficient, the best commercial UV-C LEDs in the 265–280 nm range are ~2% energy efficient; InGaN blue LEDs are 80% energy efficient. Research on AlGaN LEDs has made significant progress into AlGaN material quality (including threading dislocation density and n-AlGaN electrical conductivity) but has lagged regarding light extraction efficiency. Light extraction from UV LEDs is limited by p-GaN absorption because of the lack of p-contact to p-AlGaN with AlN fraction (AlN content > 50%). Furthermore, AlGaN emitters at the 265–280 nm range emit 40–50% of their emissions as transverse magnetic (TM) waves, which are harder to extract than transverse electric (TE) waves.

SiC is an absorbing substrate that has been largely overlooked in developing UV-C LEDs, even though it has a small lattice mismatch with AlN (~1%) and a similar Wurtzite crystal structure and is more chemically stable. We demonstrate the first lateral thin-film flip-chip (TFFC) ultraviolet (UV) light-emitting diodes grown on SiC. UV LEDs were made at 310 nm, 298 nm, 278 nm, and 265 nm.

In this dissertation, we discuss the design, epi development, and fabrication of TFFC AlGaN LEDs with reflective p-contacts. The AlGaN:Mg growth temperature and the Mg doping profile in AlGaN:Mg were found to significantly impact the electroluminescence (EL) efficiency of the AlGaN MQWs. KOH roughening enhanced the light-extraction efficiency (LEE) by 100% and by ~180–200% for UV LEDs with 10 nm p-GaN and 5 nm p-GaN, respectively, without affecting the devices’ IV characteristics. The thin-film architecture led to a high LEE of about ~28–30% without LED encapsulation when used with LEDs with 5 nm p-GaN. The best light extraction efficiency in the literature is ~24% (without LED encapsulation) for a 275 nm flip-chip LED grown on PSS sapphire substrate. KOH roughening of AlN is discussed and is compared to KOH roughening of N-Face GaN. To advance LEE further, we attempted to develop LEDs with transparent current n-AlGaN spreading layers as well as highly doped n⁺-AlGaN tunnel junctions on top of UV-C LEDs. Reflective and ohmic n-contacts with low resistivities were developed for the n-Al_.58Ga_.42N regrown by MBE. Furthermore, a highly reflective MgF₂/Al omnidirectional mirror was developed, which can be used with n-contact microgrid to further enhance the LEE in UV-C LEDs with a transparent tunnel junction.

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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.

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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.

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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.

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Thabethe, Thabsile Theodora. "The interfacial reaction and analysis of W thin film on 6H-SiC annealed in vacuum, hydrogen and argon." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/65018.

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Silicon carbide (SiC) is used as the main diffusion barrier to prevent the fission products (FPs) from escaping in high temperature reactors (HTRs). It retains most of the FPs quite effectively with the exception of silver, strontium and europium. There have also been reports on the reactions between some FPs and SiC, raising some concerns on the integrity of SiC as a coating layer and questioning the ability of SiC as the main diffusion barrier. An additional protective layer of tungsten (W) is proposed to cover the SiC and probably reduce the interaction of FPs with SiC. Coating of SiC layer with W will assist in improving the shielding effect, which will allow for high burn up and enrichment without degrading the SiC. W coatings on SiC are also used for device fabrication. (Thus this study will benefit both semiconductor and nuclear application.) The study was conducted by sputter depositing W metal thin films on 6H-SiC at room temperature (RT). The effect of thermal annealing in vacuum, hydrogen (H2) and argon (Ar) of the W thin film deposited on 6H-SiC was investigated as a function of annealing temperature. The resulting solid-state reactions, phase composition and surface structural modification were investigated using Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thickness of the as-deposited layer obtained from RUMP simulations was about 73.8 nm and was composed of about 63.4 at.% W and 36.6 at.% O. The oxygen was in a form of tungsten oxide (WO3) mixed in the W thin film. The SEM and AFM images of the as-deposited samples showed that the W thin film had a uniform surface with small grains. The surface roughness (Rrms value) of the as-deposited sample was 0.4 nm. The samples where annealed from 700 °C to 1000 °C for 1h in vacuum, hydrogen (H2), and argon (Ar). From the RBS results, the initial reaction for vacuum annealed samples occurred at 850 °C, for H2 annealed samples it was 700 °C and the Ar annealed had an initial reaction at a temperature lower than 700 °C. In all the annealing atmospheres carbon (C) was found to diffuse faster than Si into the W metal. After this C diffusion reached equilibrium, Si also migrated into the W metal. A reduction of oxygen upon annealing was observed for the vacuum annealed samples. Removal of oxygen was observed for the H2 annealed samples, while oxygen was seen to diffuse to the reaction zone (RZ) for the Ar annealed samples. The phases observed from GIXRD at 700 °C for vacuum annealed samples were CW3 and WC, for H2 samples W5Si3 and WC and for Ar annealed samples W5Si3, WC, SiO2 and W2C. The formation of WSi2 and W2C was observed at 800 °C for H2 samples and 900 °C for vacuum samples. The segregation of Si towards the surface at 1000 °C for H2 samples resulted in the formation of SiO2. The results showed that annealing in different atmospheres reduces the initial reactions and phases formed. SEM and AFM revealed that the samples annealed in Ar were rougher than the vacuum and H2 samples, while the vacuum annealed samples were rougher than the H2 annealed samples. The Rrms of the samples annealed in different atmosphere followed the order: Ar ˃ Vacuum˃ H2. From the SEM and AFM images, the H2 annealed samples at 700 °C were composed of small granules which increased with annealing temperature resulting in the formation of distinct grain boundaries. The samples annealed in Ar at 700 °C were composed of big crystals which were randomly orientated. Increase in annealing temperature for the Ar samples resulted in the parasitic growth of the crystals, which is in line with Wulf’s law. The samples annealed in vacuum at 700 °C formed tungsten oxide nanowires on the W metal surface, with the W metal in a form of granules. Annealing at high temperatures resulted in the removal of the tungsten oxide nanowires on the W metal surface and parasitic growth of the crystals. The difference in the crystal growth observed during the vacuum, H2 and Ar is explained by a crystal growth model.
Thesis (PhD)--University of Pretoria, 2017.
NRF Free-standing-Innovation Doctoral Scholarships
Physics
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Baran, Andre. "Chemical bath deposited zinc cadmium sulfide and sputter deposted [sic] zinc oxide for thin film solar cell device fabrication." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0022644.

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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.

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Thesis (Master of Sciences (Engineering))--Case Western Reserve University, 2010
Department 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

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10

Da, Conceicao Lorenzzi Jean Carlos. "Growth and doping of heteroepitaxial 3C-SiC layers on α-SiC substrates using Vapour-Liquid-Solid mechanism." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10179.

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L'utilisation récente d'une voie originale de croissance cristalline basée sur les mécanismes vapeur-liquide-solide (VLS) à partir d'un bain Ge-Si a permis des améliorations importantes de la qualité cristalline des couches minces hétéroépitaxiales de SiC-3C sur substrats sur substrat α-SiC(0001). Ce travail a pour but d'approfondir les connaissances sur cette technique de croissance, d'améliorer le procédé et de déterminer les propriétés du matériau élaboré. La première partie est dédiée à la compréhension et la maîtrise des différents mécanismes impliqués dans la croissance de SiC-3C par VLS. Cela a notamment permis la détermination des paramètres limitant la taille des échantillons et la démonstration des avantages à utiliser des alliages fondus contant 50 at% de Ge au lieu de 75 at%. Une étude de la croissance latérale sur substrats patternés a donné des indications intéressantes pouvant être intégrées dans le modèle d'élimination des macles. L'incorporation intentionnelle et non intentionnelle de dopants de type n et p pendant la croissance VLS a été suivie. Pour le dopage n, nous avons démontré l'existence d'un lien clair entre l'impureté N et la stabilisation du polytype SiC-3C. En outre, nous avons réussi à abaisser le dopage résiduel n des couches en dessous de 1x1017 cm-3. Pour le dopage p, le meilleur élément n'est pas le Ga mais l'Al, même s'il doit être ajouté à un alliage de type Si-Ge pour éviter l'homoépitaxie. Enfin, ces couches ont été caractérisées optiquement et électriquement par différentes techniques. Les mesures C-V et G-V ont permis d'estimer une concentration très faible (7×109 cm-2) de charges fixes dans l'oxyde SiO2 ainsi qu'une densité d'états d'interface aussi basse que 1.2×1010 cm-2eV-1 à 0.63 eV sous la bande de conduction. Ces valeurs record sont une très bonne base pour le développement d'un composant de type MOSFET en SiC-3C
Recently, the use of an original growth approach based on vapour-liquid-solid (VLS) mechanism with Ge-Si melts has led to significant improvement of the crystalline quality of the 3C-SiC thin layers heteroepitaxially grown on α-SiC(0001) substrate. This work tries to deepen the knowledge of such specific growth method, to improve the process and to determine the properties of the grown material. The first part was dedicated to the understanding and mastering of the various mechanisms involved in 3C-SiC growth by VLS mechanism. This led to the determination of the parameters limiting sample size and the demonstration of the benefits of using 50 at% Ge instead of 75 at% Ge melts. A study of lateral enlargement on patterned substrates gave some interesting hints which can be integrated in the model of twin defect elimination. The incorporation of non intentional and intentional n- and p-type dopants during VLS growth was studied. For n-type doping, a clear link between N impurity and 3C polytype stability was demonstrated. Besides, high purity layers with residual n-type doping below 1x1017 cm-3 were achieved. For p-type doping, the best element was shown to be Al and not Ga, even if it has to be alloyed with Ge-Si melts to avoid homoepitaxial growth. Finally, these layers were characterised by several optical and electrical means like Raman spectroscopy, low temperature photoluminescence, deep leveltransient spectroscopy and MOS capacitors measurements. Very low concentrationsof fixed oxide charges estimated about 7×109 cm-2 and interface states densities Dit equal to 1.2×1010 cm-2eV-1at 0.63 eV below the conduction band have been achieved. These record values are a very good base toward 3C-SiC MOSFET

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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.

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Deva, Reddy Jayadeep. "Mechanical Properties of Silicon Carbide (SiC) Thin Films." Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/210.

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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.

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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.

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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).

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Inoue, Shinichiro. "Ion assisted methods of deposition of SiC." Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308174.

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Ahmed, Fatema. "Structural properties and optical modelling of SiC thin films." University of the Western Cape, 2020. http://hdl.handle.net/11394/7284.

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>Magister Scientiae - MSc
Amorphous 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.

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Li, Zhiying. "Microbridge tests on galium[sic] nitride and parylene-c thin films /." View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?MECH%202010%20LI.

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Chen, Lin. "SiC Thin-Films on Insulating Substrates for Robust MEMS-Applications." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1053095076.

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Cheng, Lin. "SiC thin-films on insulating substrates for robust MEMS applications." Cincinnati, Ohio : University of Cincinnati, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1053095076.

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Carballo, Jose M. "Residual Stress Analysis in 3C-SiC Thin Films by Substrate Curvature Method." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1590.

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Development of thin films has allowed for important improvements in optical, electronic and electromechanical devices within micrometer length scales. In order to grow thin films, there exist a wide variety of deposition techniques, as each technique offers a unique set of advantages. The main challenge of thin film deposition is to reach smallest possible dimensions, while achieving mechanical stability during operating conditions (including extreme temperatures and external forces, complex film structures and device configurations). Silicon carbide (SiC) is attractive for its resistance to harsh environments, and the potential it offers to improve performance in several microelectronic, micro-electromechanical, and optoelectronic applications. The challenge is to overcome presence of high defect densities within structure of SiC while it is grown as a crystalline thin film. For this reason is important to monitor levels of residual stress, inherited from such grown defects, and which can risk the mechanical stability of SiC- made thin film devices. Stoney's equation is the theoretical foundation of the curvature method for measuring thin film residual stress. It connects residual film stress with substrate curvature through thin plates bending mechanics. Important assumptions and vii simplifications are made about the film-substrate system material properties, dimensions and loading conditions; however, accuracy is reduced upon applying such simplifications. In recent studies of cubic SiC growth, certain Stoney's equation assumptions are violated in order to obtain approximate values of residual stress average. Furthermore, several studies have proposed to expand the scope of Stoney's equation utility; however, such expansions demand of more extensive substrate deflection measurements to be made, before and after film deposition. The goal of this work is to improve the analysis of substrate deflection data, obtained by mechanical profilometry, which is a simple and inexpensive technique. Scatter in deflection data complicates the use of simple processes such as direct differentiation or polynomial fitting. One proposed method is total variation regularization of differentiation process; and results are promising for the adaptation of mechanical profilometry for complete measurement of all components of non-uniform substrate curvature.

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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.

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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.

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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.

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Hanigofsky, John. "Modeling of the chemical vapor deposition of YBa₂Cu₃O, TiB₂, and SiC thin films onto continuous ceramic tows." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/36210.

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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.

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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.

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Guerra, Torres Jorge Andrés. "Optical characterization and thermal activation of Tb doped amorphous SiC, AlN and SiN thin films." Doctoral thesis, Pontificia Universidad Católica del Perú, 2017. http://tesis.pucp.edu.pe/repositorio/handle/123456789/9187.

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En la presente tesis se evalúan las propiedades ópticas y las características de emisión de luz de películas delgadas amorfas de AlN, SiN y SiC:H dopadas con Tb. La caracterización óptica se centra en la determinación del ancho de banda, la energía de Urbach y el foco de Urbach a partir de mediciones ópticas. Se desarrolla un modelo, basado en fluctuaciones térmicas de la banda, para describir la absorción fundamental sobrepuesta con las colas de Urbach. Luego, se realiza un análisis de la existencia y significado del foco de Urbach y se contrasta con modelo anterior. Uno de los principales resultados en esta parte es la capacidad del modelo antes mencionado para distinguir las regiones de Urbach y Tauc del coeficiente de absorción. En este caso, películas delgadas de a-SiC:H depositadas en distintas condiciones de dilución de hidrógeno exhibieron un ancho de banda no correlacionado con la energía de Urbach al usar este modelo, en contraste a lo que se observa típicamente después de utilizar el modelo de Tauc. El análisis de características de emisión de luz se centra al proceso de activación térmica que sufren los iones de tierras raras cuando se calientan las muestras. El efecto de la temperatura de recocido, temperatura de la muestra y concentración de tierras raras en la intensidad de la emisión de luz se evalúa bajo fuentes de excitación de fotones y electrones. Se utiliza un modelo de tasa de transiciones para ajustar la intensidad de luz global asociada al Tb en películas delgadas de a-SiC:H:Tb3+ frente a la concentración de Tb después de diferentes temperaturas de recocido. Se recupera una energía de activación asociada a la activación térmica. Finalmente, en el caso de a-SiC: H: Tb3+, se observa una disminución del efecto de enfriamiento de la concentración, lo que sugiere un mecanismo adicional para aumentar la intensidad de emisión de luz relacionada con Tb.
In the present thesis the optical properties and light emission features of Tb-doped amorphous AlN, SiN and SiC:H thin films are assessed. The optical characterization is focused in the determination of the bandgap, Urbach energy and Urbach focus from optical measurements. A model, based on thermal band-fluctuations, to describe the fundamental absorption overlapped with Urbach tails is developed. Thenceforth, an analysis of the existence and meaning of the Urbach focus is performed and contrasted with the latter model. One of the main results in this part is the capability of aforementioned model to distinguish the Urbach and Tauc regions of the absorption coefficient. In this matter, a-SiC:H thin films grown with distinct hydrogen dilution conditions exhibited an uncorrelated bandgap with the Urbach energy when using this model, contrary to what is typically observed after applying the Tauc model. The light emission features analysis is concerned with the thermal activation process that rare earth ions suffer when annealing the samples. The effect of the annealing temperature, sample temperature and rare earth concentration on the light emission intensity is assessed under photon and electron excitation sources. A rate equation model is used to fit the overall Tb-related intensity of a-SiC:H:Tb3+ versus the Tb concentration after different annealing temperatures. An activation energy associated to the thermal activation is recovered. Finally, in the case of a-SiC:H:Tb3+ a diminution of the concentration quenching effect is observed suggesting an additional mechanism to enhance the Tb-related light emission intensity.
In dieser Arbeit werden die optischen Eigenschaften und die Lichtemission der dünnen amorphen Schichten AlN, SiN und SiC:H dotiert mit Tb untersucht. Die optische Charakterisierung beschränkt sich auf die Bestimmung der Bandlücke, der Urbachenergie und den Urbachfokus. Basierend auf thermischen Fluktuationen der Bandlücke wird ein Modell entwickelt, welches die fundamentale Absorption in Überlapp mit den Urbachausläufern beschreibt. Es wird die Existenz und die Bedeutung des Urbachfokus analysiert und mit dem vorher entwickelten Modell verglichen. Eine der wichtigsten Ergebnisse dieser Untersuchungen ist die Fähigkeit dieses Modells, den Urbach-Bereich von dem Tauc-Bereich des Abrorptionskoeffizienten zu trennen. Zum Beispiel zeigen dünne Filme aus SiC:H abgeschieden mit unterschiedlichen Wasserstoffflüssen unter Verwendung dieses Modells eine Bandlücke, die nicht mit der Urbach-Energie korreliert ist. Dies unterscheidet sich typischerweise von der Beobachtung der Bandlückenvariation unter Verwendung des Tauc-Modells. Die Untersuchung der Lichtemission konzentriert sich auf den Prozess der thermischen Aktivierung, welchen die Seltenerdionen bei Ausheilung der Proben erleiden. Der Effekt der Ausheiltemperatur, der Probentemperatur und der Konzentration der Seltenen Erden auf die Intensität der Lichtemission wird mit Anregung von Photonen und Elektronen untersucht. Es wird ein Änderungsratenmodell der Übergänge verwendet, um die globale mit Tb assoziierte Lichtemission der dünnen a-SiC:H:Tb3+, Schichten in Abhängigkeit von der Konzentration by verschiedenen Ausheiltemperaturen zu modellieren. Es konnte eine Aktivierungsenergie der thermischen Aktivierung bestimmt werden. Zuletzt beobachtet man im Falle von a-SiC:H:Tb3+ eine Verminderung der Unterdrückung der Konzentration, welches ein Hinweis darauf ist, dass ein zusätzlicher Mechanismus für die Erhöhung der Lichtemission mit der Tb Konzentration verantwortlich ist.
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Ullah, Syed Shihab. "Solution Processing Electronics Using Si6 H12 Inks: Poly-Si TFTs and Co-Si MOS Capacitors." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/28902.

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The development of new materials and processes for electronic devices has been driven by the integrated circuit (IC) industry since the dawn of the computer era. After several decades of '"Moore's Law"-type innovation, future miniaturization may be slowed down by materials and processing limitations. By way of comparison, the nascent field of flexible electronics is not driven by the smallest possible circuit dimension, but instead by cost and form-factor where features typical of 1970s CMOS (i.e., channel length - IO ?m) will enable flexible electronic technologies such as RFID, e-paper, photovoltaics and health monitoring devices. In this thesis. cyclohexasilane is proposed and used as a key reagent in solution processing of poly-Si and Co-Si thin films with the former used as the active layer in thin film transistors (TFTs) and the latter as the gate metal in metal-oxide-semiconductor (MOS) capacitors. A work function of 4.356 eV was determined for the Co-Si thin films via capacitance-voltage (C-Y) characterization which differs slightly from that extracted from ultraviolet photoemission spectroscopy (UPS) data (i.e., 4.8 eV). Simulation showed the difference between the C-V and UPS-derived data may be attributed to the existence of 8.3 x 10 (exponent 10) cm-2 interface charge density in the oxide-semiconductor junction. Poly-Si TFTs prepared using Si6 H12-based inks maintained the following electrical attributes: field effect mobility of 0.1 cm2V-1s-1; threshold voltage of 66 V; and, an on/off ratio of 1630. A BSIM3 version 3 NFET model was modified through global parametric extraction procedure to match the transfer characteristics of the fabricated poly-Si TFT. It is anticipated that this model can be utilized for future design simulation for solution-processed poly-Si circuits.

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Vijayakumar, Arun. "INVESTIGATION OF REACTIVELY SPUTTERED SILICON CARBON BORON NITRIDE (SiCBN) THIN FILMS FOR HIGH TEMPERATURE APPLICATIONS." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2143.

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The increasing demand for efficient energy systems in the last decade has brought about the development of advanced sensor systems that utilize advance detection methods to help in preventive maintenance of these essential systems. These usually are needed in hard to access environments where conditions are extreme and unfit for human interaction. Thin film based sensors deposited directly on the surfaces exposed to harsh environments can serve as ideal means of measuring the temperature of the component during operation. They provide the basic advantage of proximity to the surface and hence accurate measurement of the surface temperature. The low mass size ratio provides the additional advantage of least interference to system operation. The four elements consisting of Si, C, B, and N can be used to form binary, ternary and quaternary compounds like carbides, nitrides, which are chemically and thermally stable with extreme hardness, thermal conductivity and can be doped n- and p-type. Hence these compounds can be potential candidates for high temperature applications. This research is focused on studying sputtering as a candidate to obtain thin SiCBN films. The deposition and characterization of amorphous thin films of silicon boron carbon nitride (SiCBN) is reported. The SiCBN thin films were deposited in a radio frequency (rf) magnetron sputtering system using reactive co-sputtering of silicon carbide (SiC) and boron nitride (BN) targets. Films of different compositions were deposited by varying the ratios of argon and nitrogen gas in the sputtering ambient. Investigation of the oxidation kinetics of these materials was performed to study high temperature compatibility of the material. Surface characterization of the deposited films was performed using X-ray photoelectron spectroscopy and optical profilometry. Studies reveal that the chemical state of the films is highly sensitive to nitrogen flow ratios during sputtering. Surface analysis shows that smooth and uniform SiCBN films can be produced using this technique. Carbon and nitrogen content in the films seem to be sensitive to annealing temperatures. However depth profile studies reveal certain stoichiometric compositions to be stable after high temperature anneal up to 900ºC. Electrical and optical characteristics are also investigated with interesting results. Finally a metal semiconductor metal structure based optoelectronic device is demonstrated with excellent performance improvement over standard silicon based devices under higher temperature conditions.
Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD

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Todi, Ravi. "INVESTIGATIONS ON RF SPUTTER DEPOSITED SICN THIN FILMS FOR MEMS APPLICATIONS." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3330.

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With the rapid increase in miniaturization of mechanical components, the need for a hard, protective coatings is of great importance. In this study we investigate some of the mechanical, chemical and physical properties of the SiCN thin films. Thin films of amorphous silicon carbide nitride (a-SiCxNy) were deposited in a RF magnetron sputtering system using a powder pressed SiC target. Films with various compositions were deposited on to silicon substrate by changing the N2/Ar gas ratios during sputtering. Nano-indentation studies were performed to investigate the mechanical properties such as hardness and reduced modulus of the SiCN films. Surface morphology of the films was characterized by using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) data indicated that the chemical status is highly sensitive to the nitrogen ratios during sputtering. Further, the films were annealed in dry oxygen ambient in the temperature range of 400 – 900°C and characterized using XPS to investigate the chemical composition and oxidation kinetics at each annealing temperature. The surface roughness of these films was studied as a function of annealing temperature and film composition with the help of a "Veeco" optical profilometer. Nano-indentation studies indicated that the hardness and the reduced modulus of the film are sensitive to the N2/Ar ratio of gas flow during sputtering. AFM studies revealed that the films become smoother as the N2/Ar ratio is increased. XPS data indicated the existence of C-N phases in the as-deposited films. The study of oxidation kinetics of RF sputter deposited SiCN thin films, using XPS, suggest that N2 co-sputtering helps to suppress the formation of a surface oxide, by allowing un-bonded Si to bond with N and C inside the vacuum chamber as opposed to bonding with O in atmosphere.
M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering

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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.

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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.

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31

Peterson, Sarah M. "Influence of scale, geometry, and microstructure on the electrical properties of chemically deposited thin silver films /." Connect to title online (ProQuest), 2007. http://proquest.umi.com/pqdweb?did=1453183211&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.

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Thesis (Ph. D.)--University of Oregon, 2007.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 95-101). Also available online in ProQuest, free to University of Oregon users.

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32

Tungasmita, Sukkaneste. "Growth of wide-band gap AIN and (SiC)x(AIN)₁₋x thin films by reactive magnetron sputter deposition /." Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/tek711s.pdf.

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Desai, Darshini. "Electrical characterization of thin film CdTe solar cells." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 320 p, 2007. http://proquest.umi.com/pqdweb?did=1257806491&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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34

Chung, Tien-Kan. "Magnetoelectric coupling in layered thin film and nanostructure." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835573651&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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35

Pradhan, Sailesh. "Tensile testing of thin films /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1203573161&sid=10&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Thesis (M.S.)--Southern Illinois University Carbondale, 2006.
"Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 73-84). Also available online.

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36

Sakai, Akira, Yuji Torige, Masahisa Okada, Hiroya Ikeda, Yukio Yasuda, and Shigeaki Zaima. "Atomistic evolution of Si_{1–x–y}Ge_xC_y thin films on Si(001) surfaces." American Institute of Physics, 2001. http://hdl.handle.net/2237/6994.

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37

Gasser, Stefan Michael Gasser Stefan Michael. "I. Mettalurgy of contacts to SiC and GaN ; II. Properties and oxidation of reactively sputtered Ru-Si-O thin films /." Bern : [s.n.], 1999. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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38

Stepan, Lenka Lan-Sun. "Development and testing of a thin film nitinol heart valve." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1324380381&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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39

Guerra, Torres Jorge Andrés. "Determination of the optical bandgap of thin amorphous (SiC) 1-x (AIN) x films produced by radio frequency dual magnetron sputtering." Master's thesis, Pontificia Universidad Católica del Perú, 2010. http://tesis.pucp.edu.pe/repositorio/handle/123456789/7009.

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Películas delgadas amorfas semiconductoras de amplio ancho de banda del compuesto pseudobinario (SiC)1-x(AlN)x fueron depositadas por pulverización por un sistema de dos magnetrones de radio frecuencia sobre CaF2, MgO, Al2O3 y vidrio. Con el fin de determinar el ancho de banda óptico versus la composición de la película, se realizaron medidas espectroscópicas de la transmisión de donde el índice de refracción y el coeficiente de absorción fueron calculados y medidas espectroscópicas de la dispersión de energía (EDS) de donde la composición fue determinada. El ancho de banda óptico es determinado para cada composición a partir del coeficiente de absorción de dos maneras distintas: según el gráfico de Tauc y utilizando el gráfico de (αhν)2. la dependencia del ancho de banda con la composición x puede ser descrita por la ley empírica de Vegard para aleaciones.
Tesis

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40

Alkazaz, Malaz. "Synthèse de films minces de phases MAX par recuit thermique - Application à la formation de contacts ohmiques sur SiC." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2328/document.

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Les phases MAX sont des carbures ou nitrures ternaires dont les propriétés sont généralement décrites comme la combinaison exceptionnelle des meilleures propriétés des métaux et des céramiques. Sous forme de couches minces, ces matériaux sont prometteurs en tant que contact ohmique sur des substrats de SiC pour la microélectronique de puissance. Des approches originales dédiées à l'obtention de films minces épitaxiés des phases MAX Ti2AlN, Ti3SiC2 et Ti3(Si,Ge)C2 sont développées dans ce travail. Des recuits à 750°C de systèmes multicouches (Ti+Al)/AlN permettent ainsi de former des couches de Ti2AlN fortement texturées sur des substrats de SiC ou Al2O3. La seconde approche consiste à recuire à 1000°C des couches de TixAly ou TixGey, déposés sur 4H-SiC, pour obtenir des films minces épitaxiés de Ti3SiC2 et Ti3(Si,Ge)C2. Ces derniers présentent les caractéristiques d'un contact ohmique sur SiC
MAX phases are a family of ternary carbides or nitrides which properties are generally described as an exceptional combination of the best properties of metals and ceramics. Thin films of MAX phases being considered as good candidates for ohmic contacts on SiC substrates for power microelectronics devices, thin films of Ti2AlN and Ti3(Si,Ge)C2 were synthesized by using original approaches. Highly textured Ti2AlN thin films were so obtained by thermal annealing at 750°C of (Ti+Al)/AlN multilayers whereas epitaxial thin films of Ti3SiC2 on 4H-SiC were achieved after an annealing at 1000°C of TixAly or TixGey layers. Good ohmic contact behaviors of Ti3SiC2 layers were confirmed in this work whereas Ti2AlN thin films behave as Schottky barriers

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41

Carns, Regina C. "Patterning polymer thin films: lithographically induced self assembly and spinodal dewetting." Pomona College, 2004. http://ccdl.libraries.claremont.edu/u?/stc,5.

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In an age in which the microchip is ubiquitous, the rewards for novel methods of microfabrification are great, and the vast possibilities of nanotechnology lie just a little ahead. Various methods of microlithography offer differing benefits, and even as older techniques such as optical lithography are being refined beyond what were once considered their upper limits of resolution, new techniques show great promise for going even further once they reach their technological maturity. Recent developments in optical lithography may allow it to break the 100-nm limit even without resorting to x-rays.

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42

Ries, Ryan Scott. "Molecular thin films phospholipid bilayers and biosensors /." Diss., Restricted to subscribing institutions, 2004. http://proquest.umi.com/pqdweb?did=795970741&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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43

Cook, Benjamin Patrick. "Lubrication models for particle-laden thin films." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1456287871&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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44

Bao, Lijie. "Sputtering deposition of barium titanate film on nickel foil." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 115 p, 2009. http://proquest.umi.com/pqdweb?did=1885755791&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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45

Hou, Wei-Jen. "Hydrazine-based solution-processing of copper chalcopyrite for thin-film photovoltaics." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1998530831&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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46

Li, Chiung-Nan. "Microstructural stability of nanocrystalline LiCoO₂ cathode in lithium thin-film batteries." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1580828921&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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47

Chun, Young Jae. "Thin film NiTi endovascular stent grafts for cerebral and aortic aneurysms." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835100701&sid=7&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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48

Hartman, Jeffrey David. "Charaterization of the Growth of Aluminum Nitride and Gallium Nitride Thin Films on Hydrogen Etched and/or cleaned 6H-SiC(0001) Surfaces." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20001013-161053.

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The surface morphology and atomic structure of nitrogen doped, n-type 6H-SiC(0001)Si wafers before and after various surface preparation techniques were investigated. As-received wafers were exposed to in-situ cleaning with or without excess silicon to obtain either a (rt3 x rt3)R30° or a (3 x 3) reconstructed surface. The resulting surfaces were characterized using reflection high-energy electron diffraction, photo-electron emission microscopy, and atomic force microscopy. An atomically clean, reconstructed surface was obtained via thermal annealing at 950ºC. Cleaning with excess silicon resulted in the formation of silicon islands on the surface. The surface morphology of hydrogen etched wafers depended upon their doping concentrations. Wafers with doping concentrations of greater than or equal 2.5 x 10E18 and less than 7 x 10E17 (ND-NA)/cm3 were investigated with the former exhibiting more surface features. The microstructure of all the samples showed regions with full and half unit cell high steps. An atomically clean, ordered, stepped surface was achieved via annealing at 1030 degrees Celcius. Chemical vapor cleaning resulted in the formation of silicon islands. The initial growth of AlN and GaN thin films on the cleaned, hydrogen etched 6H-SiC(0001) substrates were investigated using PEEM and AFM. The AlN films nucleated immediately and coalesced, except in the areas of the substrate surface which contained half unit cell height steps where pits were observed. The GaN films grown at 800ºC for 2.5 minutes exhibited nucleation and three-dimensional growth along the steps. The GaN films deposited at 700° C for 2 minutes grew three-dimensionally with coalescence of the film dependent upon the step structure. Almost complete coalescence occurred in regions with unit cell high steps and incomplete coalesce occurred in regions with half unit cell height steps. Films of AlN grown for 30 minutes via GSMBE on hydrogen etched surfaces exhibited two-dimensional growth and had an RMS roughness value of 4 Å. Films grown at 1000 ° C exhibited an SK growth mode and had rocking curve FWHM of 150-200 arcsecs. MOCVD grown films on hydrogen etched wafers had an RMS roughness value of 4 Å and a XRD rocking curve FWHM of approximately 260 acrsecs.

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49

Phung, Tran M. "Developing analytical techniques using x-ray reflectivity and diffraction to study thin film systems /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251857031&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.

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Thesis (Ph. D.)--University of Oregon, 2006.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 208-221). Also available for download via the World Wide Web; free to University of Oregon users.

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50

Kamada, Rui. "Copper(indium,gallium)selenide film formation from selenization of mixed metal/metal-selenide precursors." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 226 p, 2009. http://proquest.umi.com/pqdweb?did=1654501631&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Dissertations / Theses on the topic 'SiC thin film'

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