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Keywords:

  • optical band gap;
  • semiconductors;
  • layered crystals

Abstract

The optical properties of the TlInS2xSe2(1-x)mixed crystals (0.25 ≤ x ≤ 1) have been investigated through the transmission and reflection measurements in the wavelength range of 400–1100 nm. The optical indirect band gap energies were determined by means of the analysis of the absorption data. It was found that the energy band gaps decrease with the increase of selenium atoms content in the TlInS2xSe2(1-x)mixed crystals. The transmission measurements carried out in the temperature range of 10–300 K revealed that the rates of change of the indirect band gaps with temperature are γ = –9.2×10–4 eV/K, –6.1×10–4 eV/K, –4.7×10–4 eV/K and –5.6×10–4 eV/K for TlInS2, TlInS1.5Se0.5, TlInSSe and TlInS0.5Se1.5 crystals, respectively. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)