Band anticrossing in highly mismatched group II-VI semiconductor alloys

We have successfully synthesized highly mismatched Cd{sub 1-y}Mn{sub y}O{sub x}Te{sub 1-x} alloys by high dose implantation of O ions into Cd{sub 1-y}Mn{sub y}Te 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 Cd{sub 0.38}Mn{sub 0.62}Te. The results are consistent with the band anticrossing model which predicts that a repulsive interaction between localized states of O located above the conduction band edge and the extended states of the conduction band causes the band gap reduction. A best fit of the measured band gap energies of the O ion synthesized Cd{sub 1-y}Mn{sub y}O{sub x}Te{sub 1-x} alloys using the band anticrossing model for y < 0.55 suggests an activation efficiency of only {approx}5% for implanted O in Cd{sub 1-y}Mn{sub y}Te