Microcathodoluminescence of impurity doping at gallium nitride/sapphire interfaces

We have used low-temperature cathodoluminescence spectroscopy (CLS) to probe the spatial distribution and energies of electronic defects near GaN/Al2O3 interfaces grown by hydride vapor phase epitaxy (HVPE). Cross sectional secondary electron microscopy CLS shows systematic variations in impurity/defect emissions over a wide range of HVPE GaN/Sapphire electronic properties. These data, along with electrochemical capacitance–voltage profiling and secondary ion mass spectrometry, provide a consistent picture of near-interface doping by O diffusion from Al2O3 into GaN, over a range 100–1000 nm.