Monolayer Graphene Film on ZnO Nanorod Array for High-Performance Schottky Junction Ultraviolet Photodetectors

A new Schottky junction ultraviolet photodetector (UVPD) is fabricated by coating a free‐standing ZnO nanorod (ZnONR) array with a layer of transparent monolayer graphene (MLG) film. The single‐crystalline [0001]‐oriented ZnONR array has a length of about 8–11 μm, and a diameter of 100∼600 nm. Finite element method (FEM) simulation results show that this novel nanostructure array/MLG heterojunction can trap UV photons effectively within the ZnONRs. By studying the I–V characteristics in the temperature range of 80–300 K, the barrier heights of the MLG film/ZnONR array Schottky barrier are estimated at different temperatures. Interestingly, the heterojunction diode with typical rectifying characteristics exhibits a high sensitivity to UV light illumination and a quick response of millisecond rise time/fall times with excellent reproducibility, whereas it is weakly sensitive to visible light irradiation. It is also observed that this UV photodetector (PD) is capable of monitoring a fast switching light with a frequency as high as 2250 Hz. The generality of the above results suggest that this MLG film/ZnONR array Schottky junction UVPD will have potential application in future optoelectronic devices. A new Schottky junction ultraviolet photodetector is fabricated by coating a free‐standing ZnO nanorod array with a monolayer graphene film. This special structure is able to trap UV light within ZnO nanorods, and exhibits high sensitivity to UV light irradiation with good reproducibility and fast response time.