Optical and photoelectric properties of TlInS2 layered single crystals

Single crystals of the layered compound TlInS2 were grown by direct synthesis of their constituents. The spectral and optical parameters have been determined using spectrophotometric measurements of transmittance and reflectance in the wavelength range 200-2500 nm. Absorption spectra of thin layers of TlInS2 crystals are used to study the energy gap and the interband transitions of the compound in the energy region 2-2.4 eV. The dispersion curve of the refractive index shows an anomalous dispersion in the absorption region and a normal one in the transmitted region. The direct and indirect band gaps were determined to be 2.34 and 2.258 eV, respectively. Photoconductivity measurements at room temperature resolve the structure that can be identified with the optical transition.