Papers by Keyword: Chemical Vapor Deposition Processes

Abstract: Over 80% of solar grade silicon is produced by using Siemens process. The chemical and physical phenomenon involved in the Siemens CVD reactors is very complex. For the purpose of finding the effect of gas phase reactions on the deposition rate of silicon in Siemens CVD reactors, four different gas phase reaction routes were applied in computational simulations using a commercial software Ansys Fluent. The simulation results show that the gas phase reaction mechanisms have great impact on the predicted Si growth rates. Specifically, the silicon growth rates decrease with an increase in HCl concentration on the rods’ surfaces with a fixed surface temperature. The formation of SiCl₄, however, shows insignificant impacts on the growth rate of Si, and the surface concentration of SiCl₄ is not directly associated with that of HCl.

Abstract: Both ZnO nanocomb and nanotetrapod structures have been synthesized via a simple chemical vapor deposition process in a horizontal tube furnace. The morphology of the products is affected by the distance between the source material and the deposition substrate. The formation of nanocombs has been attributed to the self-catalysis effect of polar surface. The octahedral multiple-twin model is responsible for the formation of tetrapods and tripod-like arms at the end of nanowires. The evolutive process of them has been given out in detail and the results provided valuable models in understanding crystal growth mechanisms in nanometer building-blocks and to further grow net nanostructures. And their photoluminescence properties also have been discussed.

Abstract: A simplified deposition model, involving both the description of the deposition and of the film morphology was adopted to quantitatively understand the experimental trends encountered in the epitaxial silicon carbide deposition in an industrial hot wall reactor. The attention was focused on the system involving chlorinated species because its really superior performances with respect the traditional silane/hydrocarbons process. The evolution of the crystalline structure (i.e., from poly to single) and of the surface roughness can be understood by simply comparing two characteristic times, like those inherent the surface diffusion and the matter supply to the surface.

Abstract: The present production processes for epitaxial SiC do not allow the matching of productivity with the material quality requested by the microelectronics market. Here, to respond to such a demand, a combined experimental and multi-scale – multi-hierarchy modeling approach was adopted. Models allow to verify a priori the role of process operative parameters on the performance ones for both the final product and of the process itself, like growth rate uniformity, film stoichiometry and dopants incorporation, homogeneous nucleation of particulate, microdefects and film morphology. Specifically, in this work the developing of a lumped deposition mechanism is addressed

Abstract: Boron-doped (B-doped) silicon nanowires (SiNWS) have been prepared and characterized by Raman scattering and photoluminescence (PL). B-doped SiNWS were grown by plasma enhanced chemical vapor deposition (PECVD), using diborane (B2H6) as the dopant gas. Raman spectra show a band at 480cm-1,which is attributed to amorphous silicon. Photoluminescence at room temperature exhibits three distinct emission peaks at 1.34ev,1.42ev,1.47ev. Possible reason for these is suggested. PACS: 36.40._c; 81.15.Gh; 81.20._n