Band anticrossing in group II-Ox–VI1−x highly mismatched alloys: Cd1−xMnyOxTe1−x quaternaries synthesized by O ion implantation

Highly mismatched group II-Ox–VI1−x alloys have been synthesized by oxygen implantation into Cd1−yMnyTe crystals. In crystals with y>0.02, incorporation of O causes a large decrease in the band gap. The band gap reduction increases with y; the largest value observed is 190 meV in O-implanted Cd0.38Mn0.62Te. This striking behavior is consistent with the band anticrossing model which predicts that repulsive interaction between localized states of O and the extended states of the conduction band causes the band gap reduction. These large, O-induced effects provide a unique opportunity by which to control the optical and electronic properties in II–VI alloys.