Semitransparent all-oxide p-NiO/n-ZnO nanowire ultraviolet photosensors

All-oxide ultraviolet (UV) photosensors based on NiO/ZnO nanowire heterostructure were fabricated on corning glass substrates. The p-type NiO layers were directly deposited on the ZnO nanowire arrays grown on the AZO bottom electrode/glass for the formation of a p-n diode, followed by the growth of the ITO top electrode layer for the electrical interconnection of nanostructures. The fabricated device structure showed a transmittance value of about 60% in the visible region, resulting in semitransparent properties. The current-voltage (I-V) characteristics of the fabricated p-n heterostructure showed a typical rectifying behavior with a current rise at about 4 V and an I(forward)/I(reverse) ratio of about 11.3 at 8 V. In addition, the ITO/p-NiO/n-ZnO/AZO structure responded at a wave-length position of 370 nm in reverse bias, together with weak photoresponse in the visible region. An UV sensor based on the all-oxide ZnO nanowire absorber exhibited improved photoresponse compared to the device based on a ZnO thin film.