Mechanism of donor-acceptor pair recombination in Mg-doped GaN epilayers grown on sapphire substrates

The donor-acceptor pair (DAP) recombination process was examined by performing temperature-dependent photoluminescence measurements in Mg-doped GaN epitaxial layers grown on sapphire substrates via plasma-assisted molecular beam epitaxy. Results indicated the existence of two Mg-related traps, one shallow and the other deep level. The ionization energies are 126 meV for the shallow and 160 meV for the deep level.