INFLUENCE OF VAPOR-PHASE COMPOSITION IN A GROWTH CELL ON THE DOPING LEVEL OF SILICON-CARBIDE EPITAXIAL LAYERS GROWN BY VACUUM SUBLIMATION

The influence of excess silicon in the growth cell on the doping level of SiC-6H epitaxial layers grown by vacuum sublimation has been inves tigated. It is shown that an increase in silicon vapor pressure due to a transition from SiC-C to SiC-Si systems may increase the uncompensa ted donor impurity concentration in n-type epitaxial layers by more th an an order of magnitude. The experimental data have been interpreted in terms of the difference between the positions of the donor and acce ptor impurity atoms in the SIC crystal lattice (in the carbon and sili con sublattices, respectively). The structural perfection of as-grown epitaxial layers has been studied by x-ray diffraction. (C) 1996 Ameri can Institute of Physics.