Hg_(1-x)Cd_xTe 中杂质对及双空位深能级的研究

以A.Kobayashi等的半经验紧束缚模型和Hjalmarson-Vogh-Wolford-Dow深能级理论为基础，计算了Hg1-xCdxTe中阳离子位替代式杂质（包括N,O,C）与最近邻替代式杂质形成sp3键杂质对后阳离子位杂质A1对称性深能级的变化以及最近邻理想双空位（Vc,Va）的深能级。计算结果表明：阳离子位杂质A1能级的变化取决于与其配对杂质的电负性，杂质对a1能级组分依赖关系dE/dx小于阳离子位单杂质A1能级的dE/dx,大于阴离子位单杂质T2能级的dE/dx,不同杂质对的dE/dx基本相同；理想双空位（Vc,Va）在能隙或近能隙区域产生一个a1态深能级，该能级的dE/dx很小，对于CdTe,位置在0.5eV,对于x<0.37的Hg1-xCdxTe,该能级成为导带共振态。

STUDY ON THE DEEP LEVELS OF IMPURITY PAIRS AND VACANCY PAIR IN Hg1-xCdxTe

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.