The chromium impurity photogeneration transitions in ZnS, ZnSe and ZnTe

Abstract

The results of photo-EPR and optical absorption measurements are presented for chromium doped ZnS, ZnSe and ZnTe. An analysis of these experiments enables the authors to determine the character of the absorption bands observed beneath the 'band-band' transitions as being due to the Cr2+ to Cr+ photogeneration processes. The experimental results are interpreted within the framework of the theory for the photoionisation transitions, associated with the lattice relaxation. In particular, it has been possible to establish the Eth and Eopt energies of the Cr2+ to or from Cr+ processes.