MICROSCOPIC STRUCTURE OF DX CENTERS IN CD0.8ZN0.2TE-CL

Photoexcitation of chlorine DX centers induces a transition of the Cl atoms to the shallow-donor state and persistent photoconductivity at l ow temperature in Cd0.8Zn0.2Te:Cl. The relaxation of the substitutiona l Cl atoms to the DX state at 140 K is coincident with a decrease of t he positron lineshape parameter and an increase of annihilation with h igh-momentum core electrons. The results indicate positron trapping an d annihilation at DX centers and at chlorine A centers. The data suppo rt the bond breaking model of the DX centers and the outward relaxatio n of the Cl and Cd(Zn) atoms along the [111] direction. The thermal ba rrier for the shallow-deep transition was found to be 0.44 eV.