POINT-DEFECTS RELATED TO 260 K THERMOSTIMULATED LUMINESCENCE IN ALPHA-AL2O3

Thermo- and photostimulated processes are studied in reduced hydrogen containing alpha-Al2O3 excited by UV light. It is found that UV excita tion in F absorption band at 90 K results in a ionization of the F-cen ters and capture of released electrons at defects thus producing an an isotropy absorption band at 4.2 eV and the dominant thermoluminescence (TL) peak at 260 K. The 260 K TSL peak is accompanied by complete ble aching of the 4.2 eV absorption band and vice versa-by light stimulati on in the region of the 4.2 eV band the 260 K TSL peak disappear and r eleased electrons recombine with F+-centers, Both the effect of the pr eliminary high-temperature thermal treatment of samples on formation o f 4.2 eV-centers and the observed dichroism characteristics allows to conclude that corresponding complex defect contains hydrogen and can i nvolve vacancy pair.