Fabrication of High-Responsivity Sb_2Se_3-Based Photodetectors through Selenization Process

摘要

Sb_2Se_3 has great potential for applications in near-infrared sensors because ofits narrow bandgap, environmental friendliness, and high absorption coefficient.However, the low conductivity of Sb_2Se_3 is an obstacle to the furtherdevelopment of high-performance optoelectronic devices. In this study, toaddress this challenge, the selenization process is adopted. The incorporationof Se atoms into Sb_2Se_3 facilitates the crystallization of the films and theformation of [hk0]-textured grains at a lower temperature than unselenizedSb_2Se_3. The selenized films possess larger grains than the unselenized onesat the same temperature. X-ray photoelectron spectroscopy (XPS) resultsshow that annealing causes the generation of donor-like point defects (e.g.,V_(se) and Sb_(Se)) and SeO_2. The 250 ℃-annealed selenized Sb_2Se_3-based photodetectors(PDs) have a high responsivity of 1130 mW A~(?1) and a specificdetectivity of 4.62 × 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 externalquantum efficiency of 155% at 200 μW cm~(?2). Further, the selenized PDs havegood stability to moisture and air. Based on the XPS, X-ray diffraction, andtransmission electron microscope results, the improved performance of theselenized Sb_2Se_3-based PDs is described and discussed.