Dual-functional hybrid ZnSnO/Graphene nanocomposites with applications in high-performance UV photodetectors and ozone gas sensors

Dual-functional metal oxide semiconductors that can detect the values of two different physical quantities, such as light intensity and gas concentration, have been the subject of many studies because they are used in the Internet of Things (IoT). However, the opposite sensing mechanisms for photons and gas molecules pose challenges for material design. In this study, we developed a dual-functional sensor that uses hybrid amorphous ZnSnO (a-ZTO)/graphene nanosheet (GNS) composite films. GNSs were incorporated into a-ZTO films so that the recombination process for photo-generated electron/hole pairs was suppressed owing to the favorable band alignment at the ZTO/GNS interface. The a-ZTO/GNS dual-functional sensor had a responsivity of 26.39 A/W at 350 nm and exhibited a fast response speed, with a rise time of 0.71 s and a decay time of 0.95 s. ZTO/GNS nanocomposite film also featured a smaller cluster size so that more electrons were produced for the chemical reaction of gas. Under UV illumination of 10 mW/cm(2), the dual-functional sensor exhibited a gas response of 12.8, against a 5-ppm concentration of ozone gas. These results demonstrate that this dual-functional device can serve as not only a high-performance UV photodetector but also a highly sensitive gas sensor.