The effect of low-energy electron-beam irradiation on the stability of acceptor–H complexes in Mg-doped GaN was directly examined with infra-red optical spectroscopy. It was found that Mg-H pairs began to break apart under 25keV electron-beam exposure at doses of a few mC/cm2. However, it was found that, even after long exposures, roughly 50% of the acceptor-H pairs remained unaffected by the electron exposure. Using Mg-doped samples that were vacuum-annealed and D2-gas exposed, it was demonstrated that there was a large (~×5) isotopic shift in the beam-induced de-bonding rate of these acceptor-H complexes. H and D remain in the material during these treatments, and Mg–H or Mg-D reforms during post-irradiation annealing. The implications of these observations for understanding the nature of the de-bonding process and the subsequent reactions of the detached H/D in the GaN lattice were considered.

Isotope Effects on the Rate of Electron-Beam Dissociation of Mg–H Complexes in GaN. C.H.Seager, S.M.Myers, B.Vaandrager, J.S.Nelson: Applied Physics Letters, 2002, 80[15], 2693-5