High Responsivity β-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 β-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 β-Ga₂O₃ MSM solar-blind photodetectors with graphene electrodes exhibited excellent operating characteristics including higher responsivity (∼29.8 A/W), photo-to-dark current ratio (∼1 × 10⁶%), rejection ratio (R_254nm/R_365nm, ∼9.4 × 10³), detectivity (∼1 × 10¹² 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 β-Ga₂O₃ allows maximum exposure to the incident photons, suggesting a great potential for deep UV optoelectronic applications.