ZnO based all transparent UV photodetector with functional SnO2 layer

All transparent UV photodetector based on ZnO was fabricated with structure of NiO/ZnO/SnO2/ITO by using RF and DC magnetron sputtering system. ZnO was deposited with 4 inch ZnO target (purity 99.99%) for a quality film. In order to build p-n junction up, p-Type NiO was formed on n-Type ZnO by using reactive sputtering method. The indium tin oxide (ITO) which is transparent conducting oxide (TCO) was applied as a transparent electrode for transporting electrons. To improve the UV photodetector performance, a functional SnO2 layer was selected as an electron transporting and hole blocking layer, which actively controls the carrier movement, between ZnO and ITO. The photodetector (NiO/ZnO/SnO2/ITO) shows transmittance over 50% as similar as the transmittance of a general device (NiO/ZnO/ITO) due to the high transmittance of SnO2 for broad wavelengths. The functional SnO2 layer for band alignment effectively enhances the photo-current to be 15 μA· cm-2 (from 7 μA·cm-2 of without SnO2) with the quick photo-responses of rise time (0.83 ms) and fall time (15.14 ms). We demonstrated the all transparent UV photodetector based on ZnO and suggest the route for effective designs to enhance performance for transparent photoelectric applications. © The Korean Institute of Electrical Engineers.