First-principle study on arsenic impurities and mercury vacancy in Hg1-xCdxTe

Using first principle method, we have calculated the effect of the in-situ arsenic impurity and the mercury vacancy on the bonding mechanism and the relaxation effects in the Hg_1-xCd_xTe (MCT). We have obtained the bonding charge density, density of states and novel relaxation results. The double acceptors of the mercury vacancy, and the accepter and donor levels of As_Te and As_Hg doping have been calculated, respectively. It has been found that the As impurities have the covalent bonding characteristics with host atoms. The relaxation calculations indicate that the nearest neighbor Te around the Hg vacancy defect contract toward to the defect site. The calculated results of charge density and bonding charge density reveal that the contracts relaxation attributes to the concentration of the electrons around the defect site accompanying the dangling bond reconstruction, which induce extra Coulomb interactions between the defect site and the nearest neighbour Te.