Temperature-dependent sandwich and in-plane optical characterization of ternary chalcogenide TlSbS2

We have studied the temperature-dependent optical absorption and emission mechanisms of ternary chalcogenide TlSbS2 by carrying out sandwich and planar photoconductivity, and photoluminescence measurements in the temperature range 30 K to 300 K. Two main transitions were observed in the room temperature photoconductivity spectrum at energies of 1.74 and 1.84 eV, which are attributed to a native acceptor-donor transition and a band-to-band transition, respectively. A spectral anisotropy near the bandgap energy of TlSbS2 is observed between the sandwich and in-plane photoconductivity spectrum. In the photoluminescence spectrum, we observed deep-level broadband emission which is correlated with the native defect-related transition-based freeto-bound recombination between 30 K and 70 K. The Debye temperature of TlSbS2 was found to be 280 K, and the thermal expansion coefficient was determined as 1.62 x 10-3eV/K from the analyses of its temperaturedependent photoconductivity spectra.