Investigation of luminescence properties of GaN single crystals grown on 3C-SiC substrates

Abstract

Cathodoluminescence (CL) and photoluminescence (PL) investigations of single crystal GaN grown on 3C-SiC(100) substrates by metalorganic vapor-phase epitaxy are reported. The GaN grown on 3C-SiC substrates shows distinct crystal facets. We identified the square facet and inclined facet as cubic GaN and hexagonal GaN, respectively. We studied the luminescence properties from the square facet or from the inclined facets separately by CL. For the cubic GaN, a sharp excitonic transition and a weak DA pair transition were observed from the square facet. On the other hand, an emission line at 3.293eV was obtained from the inclined facets. By studying its temperature dependence, we suggest that the 3.293eV emission is due to the free electron to acceptor transition of hexagonal GaN.