High Responsivity beta-Ga2O3 Metal-Semiconductor-Metal Solar-Blind Photodetectors with Ultraviolet Transparent Graphene Electrodes

We demonstrated high responsivity metal-semiconductor -metal (MSM) solar-blind photodetectors by integrating exfoliated beta-Ga2O3 microlayers with graphene, which is a deep ultraviolet (UV) transparent and conductive electrode. Photodetectors with MSM structures commonly suffer from low responsivity, although they feature a facile fabrication process, low dark current, and fast response speed. The beta-Ga2O3 MSM solar-blind photodetectors with graphene electrodes exhibited excellent operating characteristics including higher responsivity (similar to 29.8 A/W), photo-to-dark current ratio (similar to 1 x 10(6)%), rejection ratio (R-234nm/R-365nm, similar to 9.4 x 10(3)), detectivity (similar to 1 x 10(12) Jones), and operating speed to UV-C wavelengths, compared with MSM photodetectors with conventional metal electrodes. Absence of shading by the integration of graphene with beta-Ga2O3 allows maximum exposure to the incident photons, suggesting a great potential for deep UV optoelectronic applications.