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Electronic structure, structural and optical properties of thermally evaporated CdTe thin films

S. Lalitha·S. Zh. Karazhanov·P. Ravindran·S. Senthilarasu·R. Sathyamoorthy·J. Janabergenov
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Abstract

Thin films of CdTe were deposited on glass substrates by thermal evaporation. From the XRD measurements itis found that the films are of zinc-blende-type structure. Transmittance, absorption, extinction, and refractive coefficients are measured. Electronic structure, band parameters and optical spectra of CdTe were calculated from ab initio studies within the LDA and LDA+U approximations. It is shown that LDA underestimates the band gap, energy levels of the Cd-4d states, s-d coupling and band dispersion. However, it calculates the spin-orbit coupling correctly. LDA+U did not increase much the band gap value, but it corrected the s-d coupling by shifting the Cd-4d levels towards the experimentally determined location and by splitting the LDA-derived single s peak into two peaks, which originates from admixture of s and d states. It is shown that the sd coupling plays an important role in absorption and reflectivity constants. The calculated optical spectra fairly agree with experimental data. Independent of wave-vector scissors operator is found to be a good first approximation to shift rigidly the band gap of CdTe underestimated by LDA.

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S. Lalitha, S. Zh. Karazhanov, P. Ravindran, S. Senthilarasu, R. Sathyamoorthy, J. Janabergenov. 2006-08-05. Electronic structure, structural and optical properties of thermally evaporated CdTe thin films. https://doi.org/10.1016/j.physb.2006.04.008

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