Reduction of doping and trap concentrations in 4H–SiC epitaxial layers grown by chemical vapor deposition

High-purity and thick 4H–SiC(0001) epilayers have been grown by a horizontal hot-wall chemical vapor deposition (CVD) system, which was designed and built at the authors’ group. The background donor concentration has decreased by reducing pressure during CVD, and a low donor concentration of 1–3×1013 cm−3 was achieved by CVD growth at 80 Torr. The free exciton peaks dominated in low- and room-temperature photoluminescence spectra without titanium or point-defect related peaks. The electron mobility reaches 981 cm2/V s at room temperature and 46 200 cm2/V s at 42 K. The total trap concentration could be reduced to 4.7×1011 cm−3 by increasing the input C/Si ratio.