Changes in luminescence, under electron beam injection, were studied by means of in situ cathodoluminescence experiments on epitaxial laterally overgrown samples. It was shown that the ultra-violet peak of undoped materials exhibited a decrease in intensity as well as a noticeable red-shift. The other extrinsic peaks exhibited only an intensity decrease. However, in the case of Mg-doped materials, the ultra-violet peak intensity decrease was followed by an increase in intensity which could reach even higher values than the initial one. It was suggested that all of these features could be explained self-consistently by the occurrence of strain relaxation that resulted from the beam-enhanced diffusion of vacancies from the free surface.

Cathodoluminescence of Epitaxial GaN Laterally Overgrown on (00•1) Sapphire Substrate. Time Evolution with Low-Energy Electron Beam. S.Dassonneville, A.Amokrane, B.Sieber, J.L.Farvacque, B.Beaumont, P.Gibart, J.D.Ganière, K.Leifer: Journal of Applied Physics, 2001, 89[12], 7966-72