Cathodoluminescence imaging and temperature-dependent cathodoluminescence spectroscopy were used to probe the spatial distributions and energies of electronic defects near to GaN/Al2O3 interfaces grown by hydride vapor-phase epitaxy. Cross-sectional secondary electron microscopy imaging, cathodoluminescence spectroscopy and cathodoluminescence imaging revealed systematic variations in defect emissions with a wide range of hydride vapor-phase epitaxial-GaN/sapphire electronic properties. Highly degenerate interface regions gave rise to above-bandgap emissions due to band-filling and free-electron recombination. As well as common donor and acceptor bound excitons, cathodoluminescence spectroscopy and cathodoluminescence images also revealed emissions which were due to excitons bound to stacking faults and cubic-GaN.

Electronic Defect States Observed by Cathodoluminescence Spectroscopy at GaN/Sapphire Interfaces. X.L.Sun, S.H.Goss, L.J.Brillson, D.C.Look, R.J.Molnar: Physica Status Solidi B, 2001, 228[2], 441-4