Monograin powders were grown by recrystallization in isothermal ampoules. The conductivity of n-type samples which were quenched from 750C was high for low Na concentrations and decreased sharply, by 7 orders of magnitude, with the simultaneous appearance of photosensitivity at Na concentrations of 1018/cm3. A high n-type conductivity was attributed to the ionization of Cl-induced donor defects: ClTex → ClTeo + e’. A low conductivity at high Na levels was related to the compensation of these donors by acceptors: NaCdx + ClTeo + e’ → NaCd’ClTeo. The same complex defect could serve as one of the radiative recombination centres of the 1.4eV photoluminescence band. The 1.4eV photoluminescence band intensity increased with increasing Na content, and attained a maximum near to 1018/cm3. It then decreased suddenly. This behaviour was suggested to be caused by NaCd’Naio, or by (NaCd’Naio)2, which served as an s-center of non-radiative recombination.

Point Defects in Cl- and Na-Doped CdTe Monograin Powders M.Altosaar, P.E.Kukk, F.Mellikov: Thin Solid Films, 2000, 361-362, 443-5