Energetics and Effects of Planar Defects in CdTe

The formation energies of planar defects such as lamellar twins and intrinsic and extrinsic stacking faults in CdTe are calculated using first-principles total-energy calculations. We find that the formation energies, 16 erg/cm² for lamellar twins and 34 and 31 erg/cm² for intrinsic and extrinsic stacking faults, are very small. This explains why high densities of planar defects are always present in the fast-grown CdTe thin films. The effects of the planar defects on the formations of important point defects in p-type CdTe are also investigated. We find that the planar defects have negligible effects on Cd vacancies and substitutional Cu, whereas they lower the formation energy of Te antisites by about 0.1 eV compared to the perfect regions.