A high-response ultraviolet photodetector by integrating GaN nanoparticles with graphene

Abstract A new type of ultraviolet photodetector was fabricated by integrating GaN nanoparticles as the absorber and graphene as the carrier transport channel. The GaN nanoparticles prepared by metal-organic chemical vapor deposition exhibited the average diameter, height and density of 87.2 nm, 18.4 nm and 5 × 109/cm2, respectively. The chemical component and optical properties of the GaN nanoparticles were also confirmed and discussed. The monolayer graphene film was transferred onto GaN nanoparticles for the detector fabrication, which possessed the high crystalline quality and uniform coverage. Since the GaN nanoparticles providing trap states for the photo-generated hole, a longer carrier lifetime and higher gain would be obtained. In addition, based on the high carrier mobility of the graphene, the ultraviolet photodetector exhibited a persistent photoconduction effect and achieved a high responsivity of 200.69 A/W. The Kelvin probe force microscope measurements were carried out to reveal the device work mechanism and the carrier transport model has been established according to the decreased graphene surface potential of 0.2 eV before and after contacting with the GaN nanoparticles. Present work provides a method for obtaining new types of Ⅲ-nitrides-based ultraviolet photodetectors with high response.