Abstract:

On the basis of the semiempirical tight binding model of A.Kobayashi et al and Hjalmarson Vogl Wolford Dow theory of deep levels, in Hg 1- x Cd x Te, the deep level of ideal vacancy pair ( V c, V a) as well as the variation of the A 1 symmetric deep level of cation site substitutional impurities (N,O,C) when they are paired with nearest neighbor sp 3 bonded substitutional impurities is calculated. The results of this calculation show that the variation of the A 1 level of a cation site impurity depends on the electronegativity of its paired impurity. The energy level composition dependence ( d E/ d x) of the a 1 level of an impurity pair is smaller than that of the A 1 level of isolated cation site impurity, but is larger than that of the T 2 level of an isolated anion site impurity. Different impurity pairs have almost the same d E/ d x . The ideal vacancy pair ( V c, V a) introduces an a 1 symmetric level with very small d E/ d x near or in the band gap. For CdTe, its magnitude is about 0.5eV in CdTe. In Hg 1- x Cd x Te ( x <0.37), the level becomes a resonant state in conduction band.

Key words: Hg_1-xCd_x Te, deep level, impurit y pair, vacancy pair