The temperature dependence of optical absorption near the absorption edge of Tl3 As Se3

The optical transmission of Tl₃ As Se₃ as a function of wavelength and temperature is reported for the 1.2 – 2.5 um spectral range, and at temperatures from 40 to 300K. The absorption edge for the material occurs at about 1.011 eV. The material also indicated direct transitions at about 1.015 eV and indirect transitions at about 1.001 eV. The direct and indirect transitions are found to be independent of temperature. Electrical measurements have identified the sample as p-type, with hole concentrations of 5 × 10¹⁵ and 6 × 10¹² cm^?3 at 395 and 300K, respectively. The sample seems to be a good insulator at all temperatures between 40 ?300K.