Studies of defects in Mg doped p-GaN films grown by hydride vapor phase epitaxy on SiC substrates

Deep and shallow levels spectra, microcathodoluminescence (MCL) and electron beam induced current (EBIC) measurements on Mg doped GaN films grown by hydride vapor phase epitaxy directly on SiC are reported. It is shown that the samples contain Mg acceptors with a level at E v+0.18 eV, some unidentified shallow traps, unidentified traps with apparent activation energy of 0.25 eV, both somewhat arbitrarily attributed to interface states, and hole traps with levels at E v+0.4 and E v+0.85 eV. The latter two seem to be related to the blue and yellow luminescence bands observed in the MCL spectra. MCL and EBIC imaging of the samples reveals the presence of the network of misfit dislocations near the GaN/SiC interface. The MCL band-edge band is blue shifted in the vicinity of these defects, most likely because of the strain release near dislocations.