Local vibrational modes were studied in Mg-doped samples which had been grown by means of metalorganic chemical vapor deposition. Hetero-epitaxial layers of as-grown, thermally activated, or deuterated material were investigated by means of low-temperature Fourier-transform infra-red absorption spectroscopy. It was found that the as-grown semi-insulating material exhibited a local vibrational mode at 3125/cm. Thermal annealing reduced the intensity of this mode. Deuteration of the activated material created a local vibrational mode at 2321/cm. This isotopic shift indicated the presence of H in the vibrating complex. The new local vibrational modes were attributed to stretching modes of Mg-H and Mg-D complexes in GaN.

W.Götz, N.M.Johnson, D.P.Bour, M.D.McCluskey, E.E.Haller: Applied Physics Letters, 1996, 69[24], 3725-7