Growth And Characterization Of Low Temperature Thin Silicon And SiGe Films By UHV/CVD

This thesis work mainly involves the deposition and characterization of undoped Si].xGex single-layer and multi-layer structure as well as the studies of Sii.xGex growth kinetics. The deposition of Silicon and fabrication of SBD is also included in the article.A procedure has been developed and optimized for the deposition of high quality heteroepitaxial Si].xGex layers at temperatures from 500 to 660 ℃using Ultrahigh Vacuum Chemical Vapor Deposition (UHV/CVD) reactor with silane and germane as source gases. Three different cleaning method were examined during the Si1-xGex deposition process. The surface morphology, crystalline perfection, Ge content and stress of the deposited films were characterized by Nomarski microscopy, atomic force microscopy, high resolution X-ray diffractometry, Raman scattering spectroscopy, secondary ion mass spectrometry and TEM. The strain relaxation mechanism were studied with temperature and germanium dependencies of Si1.xGex growth modes. It was demonstrated that high quality layers of Si1-xGex single layers with germanium contents of < 0.56 could be grown on silicon substrates at temperatures 500 - 660℃.A sublinear relationship was observed between germanium incorporation and germane fraction. The amount of incorporated germanium slightly increases with increasing temperature, but decreases by raising the flow rates of source gases. The SiGex deposition rate measured in the temperature range from 500 -660 ℃ exhibits different dependencies on germanium content at different temperatures. The growth rate increases monotonically with germanium at 510℃, but at higher temperatures the rate decreases to a certain rate with higher germanium. The activation energy in Si1.xGex deposition rate was found to decrease by the addition of germanium, suggesting that the rate-limiting step was modified by germanium. By varing temperature and gas flow rates, we can propose the optimized process window to the Si1.xGex deposition.UHV/CVDThe graded-layers and multi-layers of Si].xGex are also investigated. Good quality multi-layered Sii-xGex structure were depositied using UHV/CVD- II .