Study On Solar-blind Ultraviolet Photodetector With A Ga₂O₃/graphene Hybird Structure

It has been widely used in military and civilian fields such as solar blind ultraviolet communication, missile early warning tracking, rocket tail flame detection, quantum information, space exploration, high energy physics, corona detection, environmental monitoring and biomedical.Ga2O3, a band gap of 4.9 eV, is a natural solar-blind UV material, which has received increasing attention in recent years. Two-dimensional graphene material, a good composite material, has excellent optical and electrical properties. Therefore, the combination of Ga2O3 and graphene might open up new possibilities for future UV integrated optoelectronic devices.In this paper, the transfer and characterization of graphene films and the experimental process of preparing ?-Ga2O3 thin films on transferred graphene by laser molecular beam epitaxy are studied. The effects of different substrate temperature on the structure of Ga2O3 thin films are investigated. The vertical composite structure of ?-Ga2O3/graphene solar-blind ultraviolet photodetector is prepared and its photoelectric properties are measured and analyzed. The detailed works and the main achievements are presented as follows:1. The transfer of graphene is accomplished by wet transfer technique, and the transferred monolayer graphene with smooth surface,clean and uniform thickness is obtained.2. On the transferred graphene, a high-quality ?-Ga2O3 thin film was successfully prepared. The effect of growth temperature on the crystallization quality and forbidden band width of ?-Ga2O3 thin films was studied. The crystallinity of ?-Ga2O3 thin films was the best at 850?, and the band gap of ?-Ga2O3 films was 5.11 eV.3. A new vertical composite structure graphene/?-Ga2O3/graphene solar-blind ultraviolet photodetector is further fabricated. The device exhibits an excellent solar-blind UV response at 254 nm with the light-dark ratio of 100, the responsivity of 10 A/W@10V, the switching response time of 0.96 s/0.81 s. The mechanism of the rapid response process of the device is discussed, which explains the formation process of the Schottky barrier and the principle of the device.