Temperature-dependent photoluminescence spectra mechanism analysis of N–B co-doped 4H–SiC

The temperature dependence of photoluminescence (PL) spectra of heavily N–B co-doped fluorescent SiC grown by the PVT method has been investigated. With fixed N and different B doping concentration, the luminescence intensity and position as a function of temperature were analyzed. With higher B doping concentration, it is the higher PL intensity from 40 K to 300 K and weaker blue-shift. The broad peak with energy separations show that three kinds of bands, which are free-electron-to-acceptor (e-A), donor-acceptor pair (DAP) and Band 3, are recognized from 40 K to 160 K. And only e-A and DAP emission exist from 160 K to 300 K. The luminous mechanism of the above three emission components was discussed. It is confirmed that Band 3 originated from the recombination of deep level introduced by C vacancies with conduction band electrons by EPR results, which occurs only below 160 K. Moreover, the fluorescence lifetime analyses of N–B co-doped fluorescent SiC were performed. At low temperatures, many holes are trapped in the shallow B level, resulting in a long fluorescence lifetime.