PHYSICA B-CONDENSED MATTER, vol.407, no.21, pp.4318-4322, 2012 (SCI-Expanded)
The absorption edge of undoped Tl2Ga2S3Se crystals have been studied through transmission and reflection measurements in the wavelength range 440-1100 nm and in the temperature range 10-300 K. The absorption edge was observed to shift toward lower energy values with increasing temperature. As a result, the rate of the indirect band gap variation with temperature gamma = -2.6 x 10(-4) eV/K and the absolute zero value of the band gap energy E-gi(0)=2.42 eV were obtained.