Temperature-dependent photoconductivity in β-In2S3 single crystals

The solar-energy absorption material beta-In(2)S(3) was characterized using temperature-dependent photoconductivity (PC) measurements in the temperature range between 30 and 340 K in this study, and thermoreflectance (TR) and photoluminescence (PL) measurements were carried out to identify near-band-edge transitions in the beta-In(2)S(3) tetragonal crystal. The experimental analyses of PL, PC, and TR confirmed that beta-In(2)S(3) is a direct semiconductor with a band gap of 2.073 eV at 30 K and 1.935 eV at 300 K. The PL and PC spectra manifest some defect-related features in the beta-In(2)S(3) single crystal. Two defect emissions and two band-edge luminescences were simultaneously detected in the PL spectrum at 30 K, and the temperature-dependent PC spectra of beta-In(2)S(3) from 160 to 300 K reveal an additional defectlike or band-to-band feature with an energy located above the conduction band edge (E(C)). The temperature dependences of the PC transition features in the beta-In(2)S(3) defect crystal were analyzed. The origin and mechanism of all defect states and band-edge transitions in the beta-In(2)S(3) single crystal are evaluated and discussed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3478719]