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Atomic hydrogen can neutralize the following acceptors in silicon: boron, aluminum, gallium, and indium. Up to 1019 B cm−3 have been neutralized. Hydrogen penetration seems to follow a diffusive transport that is impeded by the concentration of binding sites.

Zinc in GaN forms an efficient radiative center emitting blue light at 2.86±0.02 eV and acts as a deep acceptor which can make the crystal insulating. A systematic variation of growth conditions shows that an optimization of the photoluminescence efficiency is possible. Under nonoptimal conditions, lower photon energy emission is obtained. A temperature-dependent competing nonradiative process has an activation energy of 0.33±0.15 eV. The emission peak exhibits a negligible spectral shift with temperature. The response time of the blue photoluminescence is several orders of magnitude slower than the near-gap transition. It is suggested that the photoluminescence is due to a radiative transition from the conduction band tail to the Zn acceptor levels.

Pankove et al. Respond: Firstly, since our Letter was published we found that in some samples the boron-hydrogen complex becomes unstable above ~ 130 °C; we agree with Sah etal. 1 that this complex is dissociated above 185 °C. Therefore, we must amend the statement in our abstract that neutralization of B by H occurs 4 'between 65 and 300 °C" and restrict this to a lower range of from about 65 to about 150°C. The reason why neutralization was observed in the early 300 °C run is that the hydrogenation occurred during cooldown with the plasma on. Since then, all the experiments were made with fast cooling (a few minutes).It is well known that all the hydrogen evolves from silicon above ~ 500 °C. The only purpose for our vacuum annealing at 500°C was to restore hydrogen-free initial conditions. Secondly, we did not discuss the diffusion of hydrogen, a study we plan to do in the future. However, we do find that in a given sample the neutralization effect extends deeper with time, t, as t xll y

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