A method using CFD code PHOENICS to simulate flow and heat transfer in a rectangular chemical vapor deposition(CVD) chamber. We focus on the uniformity of heat and flow field. Two different kinds of boundary conditions at substrate, uniform wall heat flux and uniform wall temperature, are used to discuss the effects of the region of inlet, the distance from inlet to substrate, the region of outlet, Re number, and Pr number on uniformity of heat and flow field in chamber. The study finds that high shear stress and high Nu number will happen on the edge of substrate, and they can not improve the heat and flow field uniformity, We suggest that the substrate should be smaller than susceptor. In the case of uniform wall heat flux on substrate, higher shear stress and Nu number on the edge of substrate would result from the condition that the region of inlet is too big. Higher shear stress and Nu number on the region of stagnant point would result from the condition that the region of inlet is too small. Both of them are not good for uniformity. Such kinds of situations also happen in the variable of the distance from inlet to substrate. In uniform wall temperature on substrate, the condition of much higher Nu number on the edge of substrate is more obvious, which effects uniformity more seriously. The uniformity of Nu number could be improved effectively on the condition of region of inlet is 0.864*0.72, Higher distance from inlet to substrate.

Abstract The development and advancement of microelectronics technology has been very dramatic. However the cost of creating new process technology by using experiment has been very high. By using computer simulation to evaluate the performance of these equipment, we are able to achieve the same goal at a much lower cost. The reactor of chemical vapor deposition (CVD) is very important to semiconductor production process. This research use numerical method (simulation) to study the process parameters of Low-Pressure Chemical Vapor Deposition (LPCVD) of silicon (Si). In this simulation, the CVD reactor modelings are constructed and discredited by using implicit finite volume method. The grids are arranged in a staggered manner for the discretization of the governing equations. Then the SIMPLE-type algorithm is used to solve all of the discretized algebra equations. Many people in the field are beginning to realize that these challenges can no longer be tackled with the traditional trial-and-error method which have dominated the CVD technology since its beginning, and that modeling may lead to better process and equipment design, reduced costs, and improved IC manufacturing. It is also to be expected that in the future, detailed CVD simulation models will not only be used in design and optimization, but also in real-time process control. Key word: chemical vapor deposition, flow simulation, natural convection.

In this thesis, we investigated the growth of nonpolar GaN on (100) £^¡VLiAlO2 substrate by a simple chemical vapor deposition (CVD) process. Metallic gallium, NH3 and ultra-purity nitrogen were used as Ga, N sources and carrier gas. The X-ray diffraction and scanning electron microscopy were used to study the influence of growth conditions such as reaction pressure, growth temperature and deposition time on the GaN epilayer¡¦s orientation and surface morphology. It¡¦s found that pure c plane, c mixed m plane and pure m plane GaN epilayers can be grown on LiAlO2 substrates by the change of growth temperatures (950¢XC~1050¢XC) under 200 torr pressure and NH3/N2 (450/450sccm) gas flow. In addition, with longer deposition time (30min ~120min), nonpolar GaN epilayers show better crystal quality. Furthermore, atomic force microscopy, Raman spectroscopy, cathodeluminescence, transmission electron microscopy were used to study the surface morphology, stress, optical properties and microstructure of the nonpolar GaN epilayers.

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In this study, epitaxial ZnO films were grown by chemical vapor deposition (CVD) on LAO(200) substrate. This dissertation is divided into two parts. In the first parts, the growth of ZnO films on various time was investigated. In the second part, the growth of ZnO films on various pressure was investigated. In the first parts of the dissertation, high <10-10> orientation ZnO films were grown. For a long time growth, the grown ZnO films on LiAlO2 substrate have good crystallinity, as revealed by XRD In the second parts, we discuss the difference of ZnO films by varying the growth pressure. It was found that both stripe-like ZnO(10-10) films and hexagonal ZnO(0002) grain existed at lower pressure(50~75 torr), as reveal by XRD and SEM. High <10-10> orientation ZnO films were grown at higher pressure. From cross-section TEM result, we did not find considerable dislocations in the ZnO films, and the ZnO/LiAlO2 interface is shown to be smooth and with the formation of the interlayers, which represents that ZnO and LiAlO2 have some reactions below the temperature of 650 ¢J. From the selected area diffraction (SAD) patterns, the orientation relationship between ZnO and LiAlO2 was determined as [11-20]ZnO//[001]LiAlO2¡B[0001]ZnO//[010]LiAlO2.

The chemical vapor deposition growth of amorphous metallic alloys is currently of interest for potential uses in electronic devices. We have explored the use of ligands having Ru-H, Ru-N, and Ru-P bonds to study the effects of ligand selection. The synthesis and design of novel Ru dinuclear complexes using volatile ligands such as 3,5-bis-trifluoromethylpyrazolate and trimethylphosphine will be presented as well as materials characterization studies on grown films. Another class of functional materials of interest is the transition metal phosphides (TMPs) which have found applications in Li-ion batteries. Current research on TMPs is focused on obtaining materials with improved or new compositions and morphologies and on improving Li insertion/de-insertion reactions and charge carrying capacities. Traditional routes to these materials involve the use of high temperatures and pressures. The work presented here will focus on a synthetic route which employs relatively mild conditions. Surface analysis studies and the electrochemical performance of mesoporous MoP₄ for use as anode materials in Li-ion batteries will be described. / text

Graphene, a single atomic layer of sp²-bonded carbon, has been of significant interest to basic sciences and engineering. Among its unique properties are exceptional mechanical strength, from the strong carbon-carbon bond; high in-plane thermal conductivity; high carrier mobilities, since electrons and holes travel through graphene as mass-less Dirac fermions; and quantum effects (such as the quantum Hall effect), which can be observed at room temperature. In 2009, Li et al., of Professor Ruoff's research group at the University of Texas at Austin, published a seminal paper detailing the production of fairly high quality graphene grown on copper foils using chemical vapor deposition (CVD). The potential for scalability of graphene CVD processing is extremely attractive, and this is currently the most promising method for its commercial viability, particularly for transparent conductive electrodes (TCEs). Here, graphene-based TCEs are compared with TCEs made with multi-walled carbon nanotubes (MWCNTs). A novel technique to reduce the sheet resistance of MWCNT-based TCEs in half is described in detail. Even with these improvements, graphene-based TCEs outperform MWCNT-based TCEs. The decomposition of copper oxides at high temperatures in an oxygen deficient environment is characterized. The ability for the oxygen evolved from the copper foil during this decomposition to react with carbon on the surface of the copper substrate is verified. This phenomenon was used to develop a technique for getting clean pre-graphene growth copper substrates and allowing repeatable graphene nucleation results. A technique for growing large graphene domains inside a copper vapor trapping 'copper enclosure' is described. The quality of the graphene grown inside the copper enclosure is characterized and shown to be of very high quality. This technique can grow graphene domains over 0.5 mm across. Finally, a possible cause of graphene ad-layer growth on the copper surface is suggested. It is proposed that gas diffusing through the copper substrate at high temperature delaminates the graphene from the copper surface in some regions. This then allows carbon containing molecules to diffuse under the graphene and grow new graphene layers. The increased ad-layer growth in the presence of helium supports this. / text

Stuttgart, Univ., Diss., 2002.

Kaiserslautern, Universiẗat, Diss., 2002.

Universiẗat, Diss., 2001--Heidelberg.