First-principles Study on the Electronic Structures and the Optical Properties of Hg(1-x)Cd(x)Te
ABSTRACT The electronic structures and the optical properties of the direct-band-gap infrared alloy Hg(1-x)Cd(x)Te (x = 0.250, 0.375, 0.500, 0.625, 0.875, and 1.000) were obtained using the local spin density approximation (LSDA) in the density functional theory (PET). The calculated lattice constants are in agreement with these calculated using Vergard's law and the band structures of these alloys are similar. The three peaks of the imaginary part in the dielectric function reveal that the conduction bands lift with increasing a. The calculated static dielectric constants of these alloys were shown to behave as a parabolic function. The results for the loss functions and effective electronic densities show that few electrons take part in the interband transitions.
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ABSTRACT: We use a modified Becke—Johnson exchange plus a local density approximation correlation potential within the density functional theory to investigate the electronic structures of Hg1−xCdxTe and In1−xGaxAs with x being 0, 0.25, 0.5, 0.75, and 1. For both of the two series, our calculated energy gaps and dielectric functions (real part ∊1 and imaginary part ∊2) are in agreement with the corresponding experimental results with x being between 0 and 1. The calculated zero-frequency refractive index varies greatly with x for Hg1−xCdxTe, but changes little with x for In1−xGaxAs, which is consistent with the real parts of their dielectric functions. Therefore, this new approach is satisfactory to describe the electronic structures and the optical properties of the semiconductors.Chinese Physics B 01/2012; 21(1). DOI:10.1088/1674-1056/21/1/017101 · 1.60 Impact Factor