High temperature defect structure of Cd- and Te-rich CdTe

The quasichemical formalism is used to evaluate simultaneously high temperature (600-1000°C) in-situ conductivity and Hall effect measurements and tellurium atom fraction in CdTe along a three-phase curve. We show, that the electrical properties can be described only by two native defects-the cadmium interstitial being divalent donor and the cadmium vacancy as a divalent acceptor. Close to the three-phase line other native defects must be involved in the model to allow deviation from stoichiometry irrespective to the low density of electrically charged defects. A deep divalent donor Te_Cd having both levels near or below the midgap describes best all high temperature experimental data