Homoepitaxial Growth Rate Studies on Diamond (110), (111), and (100) Surfaces in a Hot-Filament Reactor

Growth rates of homoepitaxial 110, 111, and 100 diamond films were experimentally determined, for the first time, in a hot filament reactor using methane and carbon tetrachloride as the carbon source. Methane concentrations from 0.07 to 1.03 in H2 were studied at a subsum temperature of 970 C. Growth ran were found to be crystal-face dependent with respect to methane concentration, being linear or first order for the 100 orientation, sublinear for 110, and sigmoidal for 111. The observed growth kinetics of 111 suggest the viability of an acetylene mechanism for 111, along with the methyl radical mechanism at methane concentrations above 0.73. CC14 concentrations from 0.06 to 0.69 in H2 were also investigated at a substrate temperature of 970 C. Growth rate behavior was similar to that of methane for all three crystal faces. The temperature dependence of the growth rates was also crystal-orientation dependent. At subsum temperatures above 730 C, growth rates are thought to be mainly transport limited, yielding effective activation energies of 8-3, 18 or - 2, and 12 or - 4 kcalmol for 100, 110, and 111 orientations, respectively. At substrate temperatures below 730 C, growth rates are thought to be surface reaction rate-limited, with an overall effective activation energy of 50 or -19 kcalmol for the three crystal-orientations studied.