Some new features of the photoluminescence of SiC(6H), SiC(4H), and SiC(15R)

Abstract

Low temperature photoluminescence (LTPL) measurements have been performed on 6H, 4H, and 15R polytype SiC crystals. In addition to well-known emission lines close to the band gap a couple of new features could be observed. Emission lines attributed to the recombination of bound excitons at aluminum acceptors have been seen in all three polytypes. A defect interpreted as a divacancy is described for SiC(4H). In SiC(6H) emission lines due to scandium centers have been observed. Furthermore the effect of a uniaxial stress on the LTPL spectrum is investigated.