Identification of cadmium vacancy complexes in CdTe(In), CdTe(Cl) and CdTe(I) by positron annihilation with core electrons

Doppler-broadening of the 511 keV positron annihilation line was used for defect identification in CdTe materials. In electrically compensated lightly n-type CdTe(In) and lightly p-type or semi-insulating CdTe(Cl) crystals positron lifetime measurements show vacancy defects with characteristic positron lifetimes of 323 ps and 370 ps, respectively. The shapes of the high-momentum parts of the measured electron-momentum distributions indicate that both defects contain a cadmium vacancy V_Cd. The defects are assigned to vacancy-donor complexes V_Cd-In and V_Cd-Cl, respectively. A vacancy in MBE-grown CdTe(I) layers observed with a low-energy positron beam is also identified as a cadmium vacancy V_Cd which is most likely complexed with I-donors.