Growth of ZnO nanorods array on PCB for enhanced UV photosensors

Abstract

Ultraviolet (UV) photosensitive device is fabricated using ZnO nanorods array on commercially available printed circuit board (PCB). Facile open aqueous solution deposition (OASD) method is used to deposit ZnO nanorods array in a trenched region between closely spaced Cu-electrodes. X-ray diffraction (XRD) patterns confirm the wurtzite phase of ZnO nanorods arrays and scanning electron microscopy (SEM) characterizes the multidimensional growth of ZnO nanorods across the trenched part of PCB. The current-voltage (I-V) characteristics of the device in dark is analogous to the back-to-back diode behaviour. However, the device exhibits an excellent photoresponsivity wherein the photocurrent value increases by two orders of magnitude at 2 V bias under the illumination ultraviolet (UV wavelength  ~ 254 nm) light source. The enhancement in photocurrent is mainly due to formation of multiple contacts between neighbouring grain-boundaries of the nanorods arrays extending to the Cu-electrodes. The prototype optoelectronic device displays almost four-times increment in the UV photocurrent at 5 V external bias potential.