Electronic properties of Hg_1-x-y Cd_xZn_yTe

The electronic structure of Zn-containing Hg_1-xCd_x Te is investigated and the effects of Zn on the band gap and effective masses are estimated. In these studies, ZnTe is treated as an additional alloy constituent and the resulting quaternary alloy Hg_1-xCd_x Zny Te is modeled using both the virtual-crystal approximation and the coherent potential approximation. Numerical results are obtained by utilizing tight-binding band structures of the constituent compounds. Results are presented for the variation of the band gap and electron effective mass with Zn composition y for fixed Cd composition x, and for the dependence of the electron and hole effective masses on Zn composition for two different fixed band gaps in the infrared regime. The results show that Zn-induced alloy disorder effects can be important for determining both the band gap and the effective masses, but that for constant band-gap material the effective masses are almost independent of y.