Theory of the self-compensation in p-type ZnSe

Abstract

To study the microscopic origin of the instability of a Li-doped acceptor theoretically, we have performed local-density functional calculation of a Li impurity in ZnSe from the first principles using the dynamical simulated-annealing scheme. In this calculation, the acceptor nature of the Li impurity at the substitutional Zn site has been successfully obtained. It has been found that Li at a tetrahedral interstitial site acts as a donor. This result suggests that the compensation can occur due to the direct recombination of the acceptor and the donor even at room temperature, if both states coexist. We have also found another compensation mechanism; the Li impurity at a Zn site, at higher temperatures, migrates from the substitutional site to the more stable interstitial sites, then the electron ionized from interstitial Li donor kills another acceptor due to the recombination process. We also discuss a nitrogen (N) impurity as another possibility of the dopant to fabricate the stable and highly-conductive p-type ZnSe.