Structure study of GaN : Mg films by X-ray absorption near-edge structure spectroscopy

X-ray absorption near-edge fine structure (XANES) spectroscopy from N K-edg e measurement was employed to examine the crystal structure of metallorgani c vapor phase epitaxy (MOVPE) grown Mg-doped GaN (GaN:Mg) films. The result showed that Mg doping induced crystal stacking faults to occur at the film surface causing a fraction of hexagonal phase to transform into cubic phas e. As a consequence of this, XANES spectra of the films were found to vary with the dopant concentration and to lose pure hexagonal character when exa mined with the incident angle theta of the X-ray beam. Spectral characteris tic variation between the two phases allows us to estimate the phase compos ition of the samples. The trend of increasing cubic phase component in dopa nt concentration is consistent with the observed Normaski optical micrograp h. (C) 2001 Published by Elsevier Science Ltd.