The luminescence of sapphire during He+ and H+ irradiation was measured at wavelengths ranging from 190 to 820nm. The variation of the luminescence as a function of ion fluence exhibited 2 types of behavior. At low fluences, the number of F+ centers increased. At high fluences, these defects were completely (F centers) or partially (F+ centers) annihilated. This resulted from 2 concomitant mechanisms. These were conversion between F and F+ defects, and the destruction of both of the luminescent species that resulted from radiation-induced damage. By using a simple model, the cross-sections that were associated with the creation or annihilation of the F+ centers were determined. The irradiated samples were also investigated by using cathodoluminescence and Auger electron spectroscopic techniques. A higher concentration of structural defects and F+ centers was found in sample areas that had previously been ion-bombarded; leading to an unsteady behavior of the surface potential under electron excitation.

C.Jardin, B.Canut, S.M.M.Ramos: Journal of Physics D, 1996, 29[8], 2066-70