Properties of Different Room-Temperature Photoluminescence Bands in 4H-SiC Substrates Investigated by Mapping Techniques

Abstract

The room-temperature photoluminescence (RTPL) was investigated in commercial nitrogen-doped 4H-SiC substrates. In a typical RTPL spectrum of n-type 4H-SiC substrate, the ‘band-edge’ emission was similar to PL signatures that are typically attributed to free-exciton recombination in high-quality thick epitaxial layers. The origin of the deep-defect ‘red’ emission and its influence on recombination properties of SiC remain unclear. In most of the substrates in which the ‘red’ RTPL band was strong, clear reverse correlation between the ‘red’ and ‘band-edge’ RTPL intensities was observed. In contrast, direct correlation was observed between the ‘bandedge’ PL map and distribution of the net free electron concentration. There is a possibility that incorporation of nitrogen donors is influenced by (or influences) incorporation of lifetime-limiting deep defects.