Physical model of defect formation in non-stoichiometric cadmium telluride

In this work, we propose a physical model of defect formation in non-stoichiometric cadmium telluride (CdTe) by detailing the change of free energy for CdTe thin film under growth. The model explains the dependence of various intrinsic point defect densities in CdTe lattice on temperature, on Fermi level, and on vapor pressures of Cd and Te2 during physical vapor deposition (PVD). The model also establishes a physical foundation for the experimentally observed relationship between the stoichiometry of CdTe films and the vapor pressures of Cd and Te2 via the formation of various defects. The simulation results based on the model provide theoretical insights and practical guidance for experimentalists to fine tune the carrier concentration in CdTe thin films.