Investigation on sub-band gap defects aided UV to NIR broad-band low-intensity photodetection by SnO2 thin film

We report a broad-band low-intensity photodetection enriched with a good reproducibility by SnO2 thin film grown by a facile vapour-liquid-solid technique. Unprecedentedly, simple Al/SnO2/Al photoconductive device, operated at room temperature in the wavelength range from ultraviolet (300 nm) to near infra-red (800 nm) show responsivities 2.04, 0.19, 0.25 and 0.19 mA/W respectively for 300 nm, 450 nm, 550 nm & 800 nm lights indicating broad-band photodetectivity due to its sub-band gap defects. It can also detect lights with very low-intensity of 14 mu W/cm(2) (300 nm), 54 mu W/cm(2) (450 nm), 42 mu W/cm(2) (550 nm) & 12 mu W/cm(2) (800 nm) having responsivity values of 8.00, 1.02, 1.42 and 0.70 mA/W respectively. Interestingly, the defect states within the band gap causing the photosensitivity over a wide wavelength range have been proposed uniquely by a systematic successive photocurrent transient experiment using illuminations from NIR to UV region supported by the photoluminescence results. These excellent performances unambiguously demonstrate that the simple SnO2 film is promising for utilization as efficient broad-band photodetector. (C) 2020 Elsevier B.V. All rights reserved.