Fabrication of High-Responsivity Sb₂Se₃-Based Photodetectors through Selenization Process

Sb₂Se₃ has great potential for applications in near-infrared sensors because of its narrow bandgap, environmental friendliness, and high absorption coefficient. However, the low conductivity of Sb₂Se₃ is an obstacle to the further development of high-performance optoelectronic devices. In this study, to address this challenge, the selenization process is adopted. The incorporation of Se atoms into Sb₂Se₃ facilitates the crystallization of the films and the formation of [hk0]-textured grains at a lower temperature than unselenized Sb₂Se₃. The selenized films possess larger grains than the unselenized ones at the same temperature. X-ray photoelectron spectroscopy (XPS) results show that annealing causes the generation of donor-like point defects (e.g., V_se and Sb_Se) and SeO₂. The 250 °C-annealed selenized Sb₂Se₃-based photodetectors (PDs) have a high responsivity of 1130 mW A⁻¹ and a specific detectivity of 4.62 × 10¹¹ Jones. The PDs exhibit a fast response time (i.e., rise/fall time of 4.54 ms/8.50 ms), sensitivity of 94.2 at 20 mW cm⁻², and external quantum efficiency of 155% at 200 µW cm⁻². Further, the selenized PDs have good stability to moisture and air. Based on the XPS, X-ray diffraction, and transmission electron microscope results, the improved performance of the selenized Sb₂Se₃-based PDs is described and discussed.