Deformations as a tool for defect levels control I. Zero-charged te-antisite in cdte

The properties of zero-charged Te-antisite (Te 0Cd), have been examined using Ab-initio calculations. Defect energy levels and its occupancies were determined and symmetry reduction due to Jahn-Teller distortion seen. The Jahn—Teller distorted configuration places the 2A 1a defect level closer to the valence band. This defect level position coincides with "unknown deep donor" position measured in some experiments. Partial densities of states and band structures have been calculated and analyzed. Also, the influence of three types of deformations (1D, 2D and 3D) on the defect energy levels and formation energies was investigated. It was found that the 2D deformation is the most effective for opening up the band gap of the semiconductor as well as for energetically separating the 2A 1a and E a defect levels.