Photogeneration of Donor Pairs in ZnSe{Ag} Crystals

Abstract

Experimental evidence is presented that photoinduced defect reactions in ZnSe{Ag} crystals give rise to the formation of (Ag0i)2 interstitial donor pairs. As a result, the induced impurity photoconductivity spectrum shows, along with the band at 0.29 eV due to isolated Ag0i atoms, a series of narrow bands in the range 0.3–0.6 eV (quasi-line spectrum). The energy positions and relative intensities of these bands are accounted for in terms of different pair separations in (Ag0i)2 . The charge instability of Agi under band-gap excitation, associated with multiple electron trapping processes, leads to atomic instability, which gives rise to ionization-enhanced diffusion and the formation of (Ag0i)2 donor pairs.