Performance improvement in amorphous zinc tin oxide ultraviolet photodetectors using an asymmetric pair of interdigitated electrodes

Solar-blind ultraviolet (UV) photodetectors with an amorphous zinc−tin oxide (a-ZTO) sensing layer have been fabricated on alkali-free glass substrates by a sol-gel method and spin coating technique. The as-prepared a-ZTO semiconductor thin films are highly transparent (>88.5%) in the visible region and exhibit moderate electrical properties at room temperature. The effects of changes in the asymmetry ratio of the line-width of a pair of Al interdigitated electrodes on the photoelectrical characteristics of solution-processed a-ZTO metal−semiconductor−metal (MSM) UV photodetectors was investigated. These photodetector devices had good photosensing properties, and their current-voltage (I–V) characteristic exhibited obvious rectification behavior under UV light illumination when operated at bias voltages of -3 V–3 V. Experimental results showed that the responsivity and specific detectivity of the a-ZTO MSM photodetectors increased with increases in the asymmetry ratio of a pair of Al interdigital electrodes. The a-ZTO MSM UV photodetector operated at 3 V bias voltage had the best responsivity of 7.42 mA/W and the highest specific detectivity of 6.35 × 10 7 J when the asymmetry ratio of electrodes was 10:1. • The a-ZTO films are highly transparent and exhibit moderate electrical properties. • Increasing asymmetry ratio of electrodes reduce resistance of detectors in dark. • I–V curves of devices exhibit obvious rectification behavior under UV illumination. • Performance of a-ZTO photodetectors were enhanced by increasing asymmetry ratio. • Low bias-voltage driving a-ZTO photodetectors fabricated by sol-gel spin-coating.