Photoluminescence of rapid-thermal annealed Mg-doped GaN films

We report the investigation of temperature and excitation power dependence in photoluminescence spectroscopy measured in Mg-doped GaN epitaxial layers grown on sapphire by metalorganic chemical vapor deposition, The objective is to examine the effects of rapid-thermal annealing on Mg-related emissio ns. It is observed that the peak position of the 2.7-2.8 eV emission line i s a function of the device temperature and annealing conditions, The phenom enon is attributed to Coulomb-potential fluctuations in the conduction and valence band edge and impurity levels due to the Mg-related complex dissoci ation. The blue shift of the 2.7-2.8 eV emission line with increasing excit ation power provides clear evidence that a donor-acceptor recombination pro cess underlies the observed emission spectrum. In addition, quenching of mi nor peaks at 3.2 and 3.3 eV are observed and their possible origin is discu ssed. (C) 2001 Elsevier Science Ltd. All rights reserved.