Abstract
We have carried out a comparison of relations used to describe the temperature dependence of the width of the band gap in crystals. It is shown that for kT≫ℏω the well-known Varshni relation can be obtained from the non-empirical Fan expression in explicit form taking account of the phonon statistics. We have calculated the temperature coefficient bof the width of the band gap for a number of materials in the range where the high-temperature condition is not met. We have found that the Varshni relation overestimates β, whereas calculations based on the Fan expression agree with experiment.
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Fiz. Tverd. Tela (St. Petersburg) 41, 994–998 (June 1999)
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Vainshtein, I.A., Zatsepin, A.F. & Kortov, V.S. Applicability of the empirical Varshni relation for the temperature dependence of the width of the band gap. Phys. Solid State 41, 905–908 (1999). https://doi.org/10.1134/1.1130901
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DOI: https://doi.org/10.1134/1.1130901