Self-compensation in phosphorus-doped CdTe

Abstract

We investigate the self-compensation mechanism in phosphorus-doped CdTe. The formation energies, charge transition levels, and defect states of several P-related point defects susceptible to cause self-compensation are addressed by first-principles calculations. Moreover, we assess the influence of the spin-orbit coupling and supercell-size effects on the stability of AX centers, which are believed to be responsible for most of the self-compensation. We report an improved result for the lowest-energy configuration of the P interstitial (Pi) and find that the self-compensation mechanism is not due to the formation of AX centers. Under Te-rich growth conditions, (Pi) exhibits a formation energy lower than the substitutional acceptor (PTe) when the Fermi level is near the valence band, acting as compensating donor, while, for Cd-rich growth conditions, our results suggest that p-type doping is limited by the formation of (PTe-VTe) complexes.