Silicon carbide defects and luminescence centers in current heated 6H-SiC

At room temperature yellow photoluminescence with a broad peak of 2.13 eV is a well-known feature of boron-doped 6H-SiC. Usually yellow luminescence is regarded as recombination involving both the boron-related deep acceptor and donor level. But the nature of the deep level has not been clearly understood yet. We annealed 6H-SiC substrates by current in vacuum without boron injection at the temperature of 1350 and 1500 ºC. We received red and yellow luminescence in PL spectrum for the heated 6H-SiC. The luminescence was regarded as donor-acceptor pair recombination involving the deep aluminum acceptor related to the adjacent carbon vacancies and nitrogen donor or the formation of quantum well like regions of 3C-SiC in 6H-SiC matrix

Boron, aluminum, nitrogen, oxygen impurities in silicon carbide

Diffusion of boron, aluminum, and oxygen was conducted at temperatures 1600 – 1700°C. Very pure original n-SiC crystal (6H-SiC) specially grown by the Lely method annealed in oxygen during 2 h at 1700 °C, in argon during 2 h at 1700 °C, with aluminum and silicon oxide powder during 2 h, and with boron oxide and aluminum during 0.5 h. Electrical characterization of the silicon carbide samples was done by the Hall effect measurements using the square van der Pauw method to determine the sheet resistance, mobility, and free carrier concentration. The model of deep donor level as a complex of nitrogen atom replacing carbon with adjacent silicon vacancy is suggested