Nitrogen Incorporation Mechanism and Dependence of Site-Competition Epitaxy on the Total Gas Flow Rate for 6H-SiC Epitaxial Layers Grown by Chemical Vapor Deposition

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Abstract
The doping mechanism of nitrogen and the dependence of site-competition epitaxy on the flow rate of H2 carrier gas were studied for 6H-SiC epitaxial layers grown by chemical vapor deposition. The indication was that nitrogen, decomposed into a mono-atomic form (N) in the gas phase, participated in the doping process. The nitrogen decomposition and the reaction at SiC surfaces played an important role in the doping. Site-competition epitaxy for (0001)Si faces was not observed for the high flow rate of the H2 carrier gas because the nitrogen decomposition and the incorporation of the decomposed nitrogen into the epitaxial layers were suppressed by the high gas flow rate. As for (0001)C faces, neither site-competition epitaxy nor its dependence on the flow rate of the H2 carrier gas was observed. Based on the result on site-competition epitaxy, the high flow rate of the H2 carrier gas was applied to epitaxial growth on (0001)C faces in order to reduce the residual donor concentration and that as low as 1.5×1015 cm-3 was obtained for nondoped layers.