Photosensitive crystals of zinc selenide have been prepared by incorporating suitable proportions of Group VII donors (e.g., bromine) and either Group I acceptors (copper or silver) or Group V acceptors (antimony or arsenic) in crystals prepared from the vapor phase. Photoconductivity phenomena characteristic of other II-VI photoconductors, such as (a) variation of photocurrent with a power of light intensity greater than unity, (b) temperature quenching of photoconductivity, and (c) infrared quenching of photoconductivity, are also found for zinc selenide. Sensitizing centers in ZnSe: Br: Cu and ZnSe: Br: Ag have levels lying at the same distance above the top of the valence band (0.6 ev) as sensitizing centers in CdSe, even though the band gap of ZnSe is 50% larger than that of CdSe. Crystals with Group V acceptors are characterized in addition by a long-wavelength spectral response, out to 1.4 microns, associated with levels lying about 1.3 ev above the top of the valence band. By a consideration of known data on the conductivity, photoconductivity, and luminescence of II-VI compounds, a consistent correlation of donor and acceptor levels in these materials is possible.

• Received 13 February 1958

DOI:https://doi.org/10.1103/PhysRev.110.1040