NIR and UV enhanced photon detector made by diindium trichalcogenides

III-VI compounds In2S3 and In2Se3 are potential optical-absorption materials used for solar energy conversion and photon detection applications. The natural surface oxide and intrinsic chalcogen vacancies in In2X3 (X = S, Se) facilitate photoelectric conversion in near infrared (NIR) to ultraviolet (UV) region. In this work, In2S3 and In2Se3 crystals have been grown by chemical vapor transport method using ICl3 as a transport agent. The as-grown In2S3 presents beta phase with a tetragonal lattice (beta-In2S3) while In2Se3 reveals a hexagonal layer structure of alpha phase (alpha-In2Se3). The band-edge property of beta-In2S3 and alpha-In2Se3 has been evaluated by transmittance and thermoreflectance spectroscopy. The direct band gaps have been determined to be E-g = 1.935 eV for beta-In2S3, and E-g = 1.453 eV for alpha-In2Se3, respectively. The optoelectronic and photoelectric conversion properties of III-VI In2S3 and In2Se3 are examined by surface photovoltage, surface photoconductive response, photoluminescence, and photoconductivity measurements. The experimental evaluations show In2X3 a well-functional material in photoelectric conversion and photodetection from near IR to UV region with the auxiliary of intrinsic defects and surface formation oxides existed in the chalcogenides. (c) 2013 Optical Society of America