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 x 10(7) J when the asymmetry ratio of electrodes was 10:1.

Automated summary

Solar-blind ultraviolet photodetectors with an amorphous zinc-tin oxide sensing layer were fabricated and the effects of asymmetry ratio of a pair of aluminum interdigitated electrodes on the photoelectrical characteristics were investigated. The experimental results showed that the photodetectors had the best responsivity and specific detectivity when the asymmetry ratio was 10:1.