The growth of AZO nanostructures with high doping concentration using vertical reaction layer synthesizing method and their applications

This study developed a hybrid nanostructure comprising zinc oxide (ZnO) nanorods and aluminium doped ZnO (AZO) nanowalls using a chemical bath deposition method for use in near-ultraviolet (NUV) photosensors. We report on a means of tuning the morphology of ZnO nanostructure using Al thin film as a doping source. An increase in the thickness of the Al thin film causes the evolution of the morphology from nanorods to nanowalls. X-ray photoelectron spectroscopy (XPS) data indicate an increase in the concentration of Al doping from 0 to 9.59 wt.%. Transmission electron microscopy indicates that the ZnO nanorods are single-crystal formations whereas the AZO nanowalls are composed of numerous single-crystal grains. UV-vis absorption spectra revealed a new area of absorption resulting from the AZO nanostructure. The resulting photosensor was tested using a 405 nm light-emitting diode (LED) at a voltage bias of 1 V across the device, wherein a photocurrent-to-dark-current ratio of 99.5 was observed. Our results demonstrate that the low-temperature fabrication of near-UV photosensors using a novel structure comprising nanorods and nanowalls is a feasible and effective approach.