Realization of unbiased photoresponse in amorphous InGaZnO ultraviolet detector via a hole-trapping process

A metal-semiconductor-metal (MSM) structure ultraviolet photodetector has been fabricated from amorphous InGaZnO (a-IGZO) film at room temperature. The photodetector can work without consuming external power and show a responsivity of 4 mA/W. The unbiased photoresponse characteristic is attributed to the hole-trapping process occurred in the electrode/a-IGZO interface, and a physical model based on band energy theory is proposed to explain the origin of the photoresponse at zero bias in our device. Our findings may provide a way to realize unbiased photoresponse in the simple MSM structure.