Two-wavelength excited photoluminescence in 4H-SiC substrate -dependence on BGE power density-

Abstract

It is still indispensable to reduce defect densities in SiC to realize its potential superiority for power device applications. We have studied carrier recombination (CR) processes in p-type 4H-SiC substrate by our optical scheme of two wavelength excited photoluminescence (TWEPL) at 12K. The Donor acceptor pair (DAP) photo-luminescence (PL) decreased distinctly with the addition of the below gap excitation (BGE) light, which revealed the presence of CR levels whose energy location corresponds to the BGE photon energy of 0.98 eV. Its dependence on the BGE power density together with the difference obtained by the BGE energy of 1.17 eV revealed a distribution of CR levels inside the forbidden gap of SiC. The method is free from electrical contact and is applicable to whole wafer mapping.