Graphene quantum dots doped ZnO superstructure (ZnO superstructure/GQDs) for weak UV intensity photodetector application

Usually, the photoresponse performances of zinc oxide based ultraviolet (UV) photodetector can be enhanced by improving the nanostructure of zinc oxide. Here, we demonstrate a kind of weak ultraviolet intensity photodetector which bases on ZnO superstructure doped with graphene quantum dots (ZnO superstructure/GQDs). The ZnO superstructure includes a ZnO nanoflower on the top of ZnO nanorod. The nanoflower has large specific surface area that is favor to the absorption of weak UV light, and the nanorod provides a good route for carriers transport. Also, the GQDs can assist the absorption of UV and the transport of carriers. The photo-response performance of the ZnO superstructure/GQDs we measured is obtained at a working bias of 3 V and an irradiate condition of 50 mu W/cm(2), under the excitation wavelength 365 nm. The results show that ZnO superstructure/ GQDs has a low dark current (40 nA) and a good photocurrent (2.1 mu A) in a low irradiation and power supply condition, and we calculate the current ratio of on/off is about 52.5 times. Further, we discuss in-depth the synthesis mechanism of ZnO superstructure and the transport mechanism of photo-generated carriers in this paper. At the same time, we develop a UV signal acquisition and voltage conversion system, which proves the practical application reference of ZnO superstructure/GQDs for weak UV intensity photodetector.