Isochronal annealing (up to 800C, 1h, N atmosphere) was performed with, and without, ultra-violet illumination. Resultant changes in the resistivity, hole density and mobility were measured at 25C using the Van der Pauw method. Without illumination, annealing at about 550C caused the resistivity and mobility to decrease and the hole density to increase. This was consistent with the idea that the H passivation of Mg was caused by the formation of electrically inactive Mg-H complexes, and that annealing dissociated the complexes into active Mg. Illumination with light having a peak wavelength around 350nm greatly enhanced the dissociation of Mg-H complexes. It was suggested that the dissociation of Mg-H complexes could be accelerated by electronic excitation of the complexes, and/or by changes in their charge states.

Photo-Enhanced Dissociation of Hydrogen-Magnesium Complexes in Gallium Nitride Y.Kamiura, Y.Yamashita, S.Nakamura: Physica B, 1999, 273-274, 54-7