Electronic properties and chemical trends of the arsenic in situ impurities in Hg 1 − x Cd x Te : First-principles study

The structural and electronic properties of the arsenic in situ impurity in ${\mathrm{Hg}}_{1\ensuremath{-}x}{\mathrm{Cd}}_{x}\mathrm{Te}$ (MCT) have been studied by combining the full-potential linear augmented plane wave and plane-wave pseudopotential methods based on the density functional theory. The structural relaxations, the local charge density, and the densities of states were computed to investigate the impurity effects on the electronic structure. The bonding characteristic between the impurity and the host atoms was discussed by analyzing the valence and the bonding charge density. The defect levels introduced by the in situ arsenic impurity were determined by the transition energy levels which agree well with the experimental results. Based on the calculated formation energy, the chemical trends of the in situ arsenic impurity and the compensation effects between ${\mathrm{As}}_{\mathrm{Te}}$ and ${\mathrm{As}}_{\mathrm{Hg}}$ in ${\mathrm{Hg}}_{1\ensuremath{-}x}{\mathrm{Cd}}_{x}\mathrm{Te}$ have been studied systematically. A brief discussion on the activation model of the postgrowth annealing process of arsenic-doped MCT was also presented.