Single crystals of the α-phase were studied by using electron-induced X-ray emission spectroscopy and cathodoluminescence techniques. The relative intensities of optical emissions, due to F+ and F centers, were determined as a function of the electron-beam parameters and annealing treatment. It was shown that the F+ centers (O vacancies with one trapped electron) predominated when the density of the incident electron beam was increased. A similar variation was observed as the electron energy was varied from 1 to 4keV. By comparing X-ray and optical spectra, the F+ centers were deduced to be stable defects in the bulk of the sample.

F+ and F Centers in α-Al2O3 by Electron-Induced X-Ray Emission Spectroscopy and Cathodoluminescence. P.Jonnard, C.Bonnelle, G.Blaise, G.Rémond, C.Roques-Carmes: Journal of Applied Physics, 2000, 88[11], 6413-7