Cathodoluminescence imaging and temperature-dependent cathodoluminescence spectroscopy were used to probe the spatial distribution 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 showed systematic variations in defect emissions with a wide range of hydride vapor phase epitaxial GaN/sapphire electronic properties. These data, along with electrochemical capacitance–voltage profiling and secondary ion mass spectrometry provided a consistent picture of near-interface doping by O out-diffusion from Al2O3 into GaN over hundreds of nm. Low-temperature cathodoluminescence spectra exhibited a new donor level at 0.003447eV near to the interface for such samples, characteristic of O impurities spatially localized at the nanoscale interface. Cathodoluminescence spectroscopy emissions indicated the formation of amorphous Al–N–O complexes at 3.8eV extending into the Al2O3 near to the GaN/sapphire interface. Cathodoluminescence spectroscopy and cathodoluminescence images also revealed emissions due to excitons bound to stacking faults and cubic phase GaN. The temperature dependence of various optical transitions at 10 to 300K provided additional information to identify the near-interface defects and impurity doping.

Depth-Dependent Investigation of Defects and Impurity Doping in GaN/Sapphire using Scanning Electron Microscopy and Cathodoluminescence Spectroscopy. X.L.Sun, S.H.Goss, L.J.Brillson, D.C.Look, R.J.Molnar: Journal of Applied Physics, 2002, 91[10], 6729-38