Epitaxial growth and properties of SiC layers grown on α-SiC(0001) by solid-source MBE: a photoluminescence study

SiC layers were grown on hexagonal (or α-)SiC(0001) by means of solid-source molecular beam epitaxy. The layers were investigated by photoluminescence at 4.2 K. The dominant emission lines in the spectra for all polytypes were attributed to the recombination of bound excitons at a D1-center. The intensity of the centre lines was found to increase for layers of higher perfection and doped by boron, resp. No influence was found regarding a change of the chemical potential from more carbon-rich to Si-rich conditions. A shift of 2 meV to lower energies of the D1-center lines connected with a decrease in intensity was detected for 3C-SiC layers of high twin-boundaries density. The obtained results support the earlier interpretation of the nature of the D1-center to be result from a carbon-divacancy. The spectrum of intentionally boron-doped samples exhibits the characteristic signature of the shallow boron-related neutral four particle bound exciton complex.