Carrier lifetimes in SiC, studied by time resolved photoluminescence spectroscopy

Abstract

Abstract Recent results regarding the time decay of carrier and exciton recombination in different SiC polytypes are presented. The recombination of bound excitons, bound both at the nitrogen donor and at the Al acceptor, is extremely fast in 4H- and 6H-SiC. These are therefore dominated by efficient non-radiative recombinations, assumed to be a phonon-less Auger process. In high quality epitaxial layers where the free exciton is present, all decay times are determined by the free exciton lifetime. Typically the free exciton also dominates recombination at intermediate temperatures, while the measured time decay at high temperatures is determined by the minority carrier lifetime. A significant improvement in the minority carrier lifetime of 4H-SiC in particular has been obtained over the past two years, with values as high as 2 μs. The minority carrier lifetime is probably determined by capture at unidentified deep levels.