All Transparent Metal Oxide Ultraviolet Photodetector

A high-performing UV photodetector that uses large energy bandgap materials of p-type NiO and n-type ZnO without an opaque metal electrode is reported. A quality heterojunction is formed by large-area applicable sputtering deposition method that has an extremely low saturation current density of 0.1 mu A cm(-2). This abrupt p-NiO/n-ZnO heterojunction device is visible-light transparent and shows the fastest photoresponse time of 24 ms among NiO-based UV photodetectors, along with the highest responsivity (3.85 A W-1) and excellent detectivity (9.6 x 10(13) Jones) properties. Structural, physical, optical, and electrical properties of nanocrystalline NiO are systematically investigated. Mott-Schottky analyses are applied to develop the interface of NiO and ZnO by establishing energy diagrams. Defects existing inside the nanocrystalline NiO film enhance the UV detection performance by defect-assisted carrier transportation. The results provide a solid scheme of manipulation of NiO defects for functional photoelectric device applications.