The optical activation of Zn ions which had been implanted into an epitaxial film was carried out by annealing in N2 pressures of up to 1.6GPa. Such pressures avoided decomposition, and could increase the annealing temperature to up to 1550C, instead of the 1000 to 1100C which could be used at ambient pressures. The Zn acceptor-related photoluminescence intensity in implanted samples was maximized by annealing at temperatures above 1350C. The Zn photoluminescence intensity then exceeded, by a factor of 15, that of epitaxially Zn-doped GaN with a comparable Zn concentration. High-pressure annealing led to a significant diffusion of implanted Zn atoms in the films. It was also possible to diffuse Zn into the implanted/unimplanted layers from external sources. The presence of high dislocation densities strongly accelerated Zn diffusion.

T.Suski, J.Jun, M.Leszczynski, H.Teisseyre, S.Strite, A.Rockett, A.Pelzmann, M.Kamp, K.J.Ebeling: Journal of Applied Physics, 1998, 84[2], 1155-7