Doping effect of boron in Hg0.75Cd0.25Te: first-principles study

Using the first-principles method based on the density functional theory, we study the doping effect of B impurity in HgCdTe (MCT). We find that the most stable configuration of the impurity is at the B hexagonal interstitial position, rather than at the in-situ substitution. The electronic structures and the density of states of B hexagonal interstitial doped MCT are systematically investigated. Near neighbour (NN) and next-near-neighbor (NNN) atoms around the B impurity are obviously relaxed. The relaxation induces the breaking of NN Te-Hg covalent bond. Moreover, B hexagonal interstitial behaves as triple n-type dopant. The charged state analysis indicates that B-i(h)(2Hg1Cd) with three positive charges is most stable and forms an effecient donor. However, as long as the Hg vacancy exists, complex impurity between Hg vacancy and B impurity can be easily formed, its binding energy reaches up to 0.96 eV. Such complex behaves as single n-type dopant. Considering radiation damage of B ion implantation, the complex is a main factor restricting the activation of B ion in MCT.