Native defects in undoped and Ag-doped Hg0.78Cd0.22Te were studied by using positron annihilation techniques. In the case of undoped specimens, the concentration of vacancy-type defects in sub-surface regions (up to 500nm) was higher than that in the bulk. This was attributed to the introduction of VHg which resulted from the diffusion of Hg atoms out of the specimen. Before Ag doping, the main type of vacancy-type defect in the p-type specimens was VHg; at concentrations of about 6 x 1015/cm3. After Ag doping, the concentration of vacancy-type defects was below the positron annihilation detection limit (1014/cm3). This was attributed to the occupation of Hg sites by Ag atoms, and to a resultant decrease in the concentration of VHg. No large change in the concentration of vacancy-type defects was observed in Ag-doped specimens before and after thermal treatment. It was concluded that the diffusion of Ag atoms was unlikely to involve interaction between Ag atoms and VHg.
A.Uedono, K.Ozaki, H.Ebe, T.Moriya, S.Tanigawa, K.Yamamoto, Y.Miyamoto: Japanese Journal of Applied Physics - 1, 1997, 36, 6661-7