NATIVE DEFECT EQUILIBRIUM IN SEMIINSULATING CDTE(CL)

CdTe single crystals doped with Cl were grown by normal freezing from a Te-rich solution. The results of charge carrier transport measurements were used to investigate the semi-insulating properties of CdTe(Cl) samples. Using the results of the theoretical calculation of the total energy, it was shown that Cd vacancies V(Cd) are the dominant defects on the Te-rich side of the phase diagram. The deep acceptor level, probably connected to the second ionized state of divalent V(Cd)) was determined to be E(a2) almost-equal-to 0.65 eV. The probabilities of the occurrence of free vacancies, vacancies bound into acceptor complexes (V(Cd)Cl(Te)) and neutral complexes (V(Cd)2Cl(Te)) theoretically determined for various possible distances in the zincblende structure were used to explain the semi-insulating properties.