@article {Bube1958, title = {Photoconductivity of Zinc Selenide Crystals and a Correlation of Donor and Acceptor Levels in II-VI Photoconductors}, journal = {Phys. Rev.}, volume = {110}, year = {1958}, month = {Jun}, pages = {1040{\textendash}1049}, abstract = {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.}, doi = {10.1103/PhysRev.110.1040}, url = {http://link.aps.org/doi/10.1103/PhysRev.110.1040} }