It was observed that photo-excitation of Cl DX centers induced a transition of the Cl atoms to the shallow-donor state, as well as a persistent photoconductivity, at low temperatures in Cl-doped Cd0.8Zn0.2Te. Relaxation of the substitutional Cl atoms to the DX state at 140K coincided with a decrease in the positron line-shape parameter, and an increase in annihilation with high-momentum core electrons. The results indicated the occurrence of positron trapping and annihilation at DX centers and Cl A-centers. These data supported the bond-breaking model for DX centers, and the outward relaxation of Cl and Cd(Zn) atoms along the [111] direction. The thermal barrier to the shallow-deep transition was estimated to be equal to 0.44eV.

Y.Y.Shan, K.G.Lynn, C.Szeles, P.Asoka-Kumar, T.Thio, J.W.Bennett, C.B.Beling, S.Fung, P.Becla: Physical Review Letters, 1997, 79[22], 4473-6