On the nature of the D1-defect center in SiC: A photoluminescence study of layers grown by solid-source molecular-beam epitaxy

Abstract

Undoped and boron-doped SiC layers are grown on hexagonal SiC(0001) substrates by means of solid-source molecular-beam epitaxy. Hexagonal 4H– and 6H–SiC layers are grown homoepitaxially via step-controlled epitaxy, whereas the cubic 3C–SiC is grown pseudomorphically via nucleation and subsequent step flow. The low-temperature photoluminescence spectra only show the well-known emission lines of the so-called $D_1$ center. The line positions are compared with results of first-principles calculations. The growth conditions, the line shape, and the line shift with the polytype support an interpretation as bound-exciton recombination at a native-defect complex that contains a Si vacancy.