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 degrees C-annealed selenized Sb2Se3-based photodetectors (PDs) have a high responsivity of 1130 mW A(-1) and a specific detectivity of 4.62 x 10(11) 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 mu W 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.