Detection of Cr impurities in GaN by room temperature cathodoluminescence spectroscopy

Trace levels of Cr impurities in epitaxial GaN grown on sapphire substrates were investigated using cathodoluminescence (CL) spectroscopy. CL emission s characteristic of Cr in an octahedral crystal field were observed from be ta-Ga2O3 overlayers produced on GaN by post-growth thermal annealing in dry O-2. Cr luminescence was also observed from the sapphire substrates, a lik ely source of the Cr contaminant. The presented results illustrate the use of beta-Ga2O3 overlayers as high sensitivity indicators of the presence of Cr in GaN. (C) 1999 American Institute of Physics. [S0003-6951(99)03651-7].