Metal-organic vapor-phase epitaxially grown GaN films were studied by using beam positron annihilation spectroscopy. Positron lifetime and Doppler broadening of annihilation radiation measurements indicated that defects, probably Ga vacancies, were reduced in concentration when films were doped with Mg, as previously observed by other workers. In lightly doped films an homogeneous layer with a minimum defect concentration was present from just below the surface, to a depth of around 0.1µm. For heavily-doped films, there was evidence of a further substantial decrease in the defect concentration following an anneal to 900C.

Characterization of Mg Doped GaN by Positron Annihilation Spectroscopy. J.Moxom, J.Xu, R.Suzuki, T.Ohdaira, G.Brandes, J.S.Flynn: Journal of Applied Physics, 2002, 92[4], 1898-901