Optical properties of Tl2In2Se3S layered single crystals |
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Authors: | İ. Guler N.M. Gasanly |
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Affiliation: | 1. Department of Physics , Middle East Technical University , 06531 Ankara, Turkey ikocer@metu.edu.tr;3. Department of Physics , Middle East Technical University , 06531 Ankara, Turkey |
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Abstract: | The optical properties of Tl2In2Se3S layered single crystals have been analyzed using transmission and reflection measurements in the wavelength region between 500 and 1100 nm. The optical indirect transitions with a band gap energy of 1.96 eV and direct transitions with a band gap energy of 2.16 eV were determined from analysis of absorption data at room temperature. Dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single-effective-oscillator model. The refractive index dispersion parameters – oscillator energy, dispersion energy, oscillator strength and zero-frequency refractive index – were found to be 4.67 eV, 45.35 eV, 1.38 × 1014 m ? 2 and 3.27, respectively. Transmission measurements were also performed in the temperature range 10–300 K. As a result of temperature-dependent transmission measurements, the rate of change in the indirect band gap with temperature, i.e. γ = ?5.6 × 10?4 eV/K, and the absolute zero value of the band gap energy, E gi(0) = 2.09 eV, were obtained. |
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Keywords: | optical properties refractive index semiconductors energy band gap |
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