Photoconductive UV detectors on sol–gel-synthesized ZnO films

Abstract We report on the photoconductive UV detector on sol–gel synthesized ZnO film based on Au–ZnO metal–semiconductor junction. I – V characteristics of these devices are perfect Ohmic in nature. Photocurrent is maximum at around 350 nm, and later a more than two-fold drop in the value was measured above 400 nm. Room temperature photoluminescence spectrum of ZnO exhibits two peaks, one in the UV region and another in the visible region, the latter being dominated due to the presence of deep-level defect states. The responsivity is increased linearly with the bias voltage. The responsivity as high as 0.040 A/W and a quantum efficiency of 14% were achieved at 350 nm. The photoresponse decay in these devices is slow.