The optical properties of GaN films doped with magnesium concentrations of the order of 1018 and 1019 cm-3 have been analyzed by picosecond time-resolved cathodoluminescence spectroscopy. Two luminescence bands in the vicinity of ∼3.45 and ∼3.27 eV are observed to increase in intensity with Mg concentration. They have been identified as related to acceptor-bound exciton and donor-acceptor pair (DAP) transitions, respectively. Time-resolved cathodoluminescence spectra, taken at low temperatures (∼4 K), show that the lifetime of the DAP peak (3.27 eV) and of what appears to be its first longitudinal-optical phonon replica at ∼3.19 eV decrease with increasing Mg concentration. These peaks differ in their recombination kinetics, strongly suggesting the existence of an underlying broad emission band which may be related to Mg.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)