TIME-RESOLVED SPECTROSCOPY OF DEFECTS IN SIC

Recent time resolved optical measurements of carrier and exciton recom bination in different SiC polytypes are presented. The recombination o f bound excitons, both bound at the nitrogen donor and at the Al accep tor, is extremely fast in 4H and 6H SiC. These recombinations are thus dominated by efficient non-radiative recombinations: assumed to be a phononless kuger process. In high quality epitaxial layers where a fre e exciton is present, all decay times are determined by the free excit on lifetime. Time resolved luminescence measurements have also been us ed to measure the minority carrier lifetime mainly in 4H SiC. A signif icant improvement of the minority carrier lifetime has been obtained i n the last two years, with values as high as 2 mu s.