Carrier lifetime in conductive and vanadium-doped 6H-SiC substrates

Conductive undoped and semi-insulating vanadium-doped 6H-SiC substrates were studied using the light-induced transient grating technique and photoluminescence (PL) spectroscopy. Carrier lifetime of 400+/-10 ps and diffusion coefficient of 2.7+/-0.2 cm(2) s(-1) were obtained for the nominally undoped wafer, while the corresponding parameters for the V-doped wafer were estimated to be 130+/-5 ps and 0.9+/-0.5 cm(2) s(-1), respectively. The peak PL intensity in the vanadium-doped wafers is more than three orders of magnitude lower than that in nominally undoped wafers. Low-temperature cw PL spectra revealed a band peaked at 507 nm, which is caused by V doping. (C) 2004 American Institute of Physics.