Photoluminescence of rapid-thermal annealed Mg-doped GaN films

We report investigation of temperature and excitation power dependencies in photoluminescence spectroscopy measured from 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 emissions. It is observed that the peak position of the 2.7~2.8 eV emission line is a function of the device temperature and detailed annealing procedure. The phenomenon is attributed to Coulomb-potential fluctuations in the conduction and valence bandedges and impurity levels due to the Mg-related complex dissociation. The blue shifts of the 2.7~2.8 eV emission lines with increasing excitation power provides clear evidence that donor-acceptor recombination process underlies the observed emission spectrum