Crystal structure and optical performance in bulk γ-InSe single crystals

Abstract

High purity γ-phase InSe single crystals have been synthesized and characterized by XRD, SEM, EDS and TEM. Detailed temperature dependent Raman and photoluminescence spectroscopy suggests a small blue-shift as temperature decreases. The corresponding blue shift in Raman and photoluminescence can be explained in terms of self-energy and the lattice parameter change induced variation of band gap, respectively. Moreover, bulk InSe exhibits photoresponsivity in a wide spectrum from 400 to 990 nm. The maximum photoresponsivity reaches up to 8.82 mA/W under the wavelength of 800 nm, which is consistent with high absorption at the wavelength.