CdTe .2. Defect chemistry

A statistical thermodynamic derivation of the equilibrium equations for two defect models for CdTe(s) at high temperatures is given. In the first the predominant defects are assumed to be doubly ionizable Cd vacancy accepters and singly ionizable Te antisite donors in Te rich material and doubly ionizable Te vacancy donors in Cd rich material. A variant in which the Te antisite defect is neutral is readily extracted from the equations by setting the donor level far enough below the conduction band edge. In the second model the Te antisite defect is replaced by a neutral Te interstitial defect. The models are then applied to the high temperature data. It is concluded that the singly ionizable Te antisite model gives the best overall fit and various high temperature properties are calculated with two sets of the adjustable parameters.