Performance evaluation of transparent self-powered n-ZnO/p-NiO heterojunction ultraviolet photosensors

Abstract

We have constructed NiO/ZnO thin film heterojunction diodes by dc magnetron sputtering technique and evaluated their performance for ultraviolet sensor applications. The constructed device configuration, ITO/ZnO/NiO/Ag exhibited excellent current-voltage rectifying characteristics in the order of 10 5 at room temperature. The effect of rapid thermal annealing treatment on the fabricated ITO/ZnO/NiO thin film stack was evaluated for their photodetector characteristics. The structural, optical, and spectroscopic properties were also investigated. Further, the ITO/ZnO/NiO/Ag diodes were tested under 365 nm UV light illumination having a power density of 0.06 mW/cm 2 . Remarkably, a speed of response with rise/fall time of 197.29/537.10 ms has been recorded at self-powered mode. Interestingly, the photodiode device has exhibited a spectral responsivity of 13.01 mA/W and stable photo detectivity of 5.66 × 10 11 Jones at room temperature. The n-ZnO/p-NiO heterojunction photodetector has shown its ability to detect a faint UV light in a self-powered mode. • Fabricated transparent p-NiO/n-ZnO heterojunction by dc magnetron sputtering with an excellent photo-to-dark current ratio. • It operated in a self-powered mode under 365 nm wavelength of a low optical power source i.e., 0.06 mW/cm 2 . • Achieved excellent speed of response of rising and fall time of 197.29 ms and 537.10 ms respectively. • At Zero bias, responsivity varied from 13.01 mA/W to 6.52 mA/W and EQE 4.42 % to 2.21 % as a function of rapid thermal annealing.