Deep levels in GaN grown by nitridation of GaAs (110) surface in a electron cyclotron-resonance ammonia plasma

The native defects in GaN synthesized by the nitridation of GaAs surfaces ( 110) in electron-cyclotron resonance-induced ammonia plasma have been monit ored by using a thermally stimulated exo-electron emission spectroscopy. A pair of defects separated by an energy 0.04 eV have been identified in the films deposited for varying periods of time. The average energies of these two defect levels were found to be 0.59 and 0.64 eV. They have been correla ted to the E2 and E3 levels in GaN, respectively, as reported by earlier wo rkers. Stoichiometry of the nitrided films was studied by X-ray photoelectr on spectroscopy; which was found to be uniform throughout the nitrided regi on. The films showed broad photoluminescence spectra centered at 360 nm and a tailing part towards longer wavelength. This feature has been explained to arise from the existence of the mixed phases under the existing plasma c onditions. Scanning electron microscopy and atomic force microscopic studie s showed that the film consisted of nanocrystalline globules with average g rain size of 50 nm. (C) 1999 Elsevier Science Ltd. All rights reserved.