Prepared for publication in
Materials Research Society Symposium ProceedingsRice University Department of Chemistry Houston, TX 77251-1892
92-18875
May29,1992Reproduction, in whole or in part, is permitted for any purpose of the United States Government.This document has been approved for public release and sale; its distribution is unlimited.
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ABSTRACT (Maximum 200 words)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 substrate temperature of 970 C. Growth rates were found to be crystal-face dependent with respect to methane concentration, being linear or first orderfor 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 substrate temperatures above 730 "C, growth rates are thought to be mainly transport limited, yielding effective activation energies of 8±3, 18±2, and 12±4 kcal/mol 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±19 kcal/mol for the three crystal-orientations studied.14. (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 substrate temperature of 970 0 C. Growth rates 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 (11). 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 0 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 substrate temperatures above 730°C, growth rates are thought to be mainly transport limited, yielding effective activation energies of 8.3, 18±2, and 12±4 kcal/mole for (100), (110), and (111) orientations, respectively. At substrate temperatures below 730*C, growth rates are thought ...
