Ionizing-irradiation-induced thermally stimulated currents in Al2O3 : Mg

The thermally stimulated currents (TSC) processes induced by ultraviolet li ght and x-ray irradiation at low temperature in oxidized magnesium-doped al uminum oxide single crystals has been studied between 80 and 300 K. It has been found that the main TSC process shows the same behavior as the main th ermally stimulated polarization (TSP) process with respect to peak temperat ure, activation energy, and sample-thickness and thermal-treatment dependen ces. It is concluded that this TSC process, as it was also the case of the TSP one, arises from the thermally activated ionization of Mg-Al(x) centers and is due to the existence of blocking contacts at the sample-electrode i nterfaces. The observed irradiation-induced decrease in the thermally stimu lated depolarization (TSD) currents can also be explained in the frame of t he stimulated dieletric-relaxation-currents theory previously applied to th e TSP and TSD phenomena in such metal-insulator-metal systems with blocking contacts. [S0163-1829(99)02011-1].