Photodetecting properties on Sn-doped Bi2S3 thin film fabricated by nebulizer spray pyrolysis technique

Abstract

Metal chalcogenides have recently gained intensive attention due to their tunable bandgap energy, optoelectronic characteristics, and exceptional optical absorption. Because of the potential advantage of photodetectors, photovoltaic, holographic recording systems, and field-effect transistors, bismuth tri-sulfide (Bi2S3) crystals, in particular, have attracted a lot of focus in scientific research. In this study, the low-cost nebulizer spray technique was employed to synthesize the proposed Bi2S3:Sn thin films on glass substrates, varying the Sn doping concentrations in Bi2S3 films (from 1 to 3%). The crystallites of the orthorhombic-structured polycrystalline Bi2S3 films were all oriented in the same direction (130). According to the XRD spectra, preferred orientation and crystalline quality were improved by Sn doping concentrations up to 2%, but, above 2% of the Sn doping ratio, the structural properties were decreased. With increasing Sn-doping levels, the estimated direct band gap (Eg) of the Bi2S3:Sn films decreased, reaching a low value of 2.01 eV at 2% Sn and then rising. A field emission scanning electron microscope (FESEM) was applied to determine the size and shape of the grains in prepared Sn: Bi2S3 films.The 2% Sn-doped Bi2S3 thin film may be more appropriate for high-speed optoelectronic devices due to its high responsivity (1.24 AW−1), external quantum efficiency (40%), and detectivity properties (1.83 × 1010Jones). A potential mechanism for photodetector performance in the presence of air and UV radiation was also discussed in the present work for the proposed Sn: Bi2S3 thin films.