A Heterostructured Graphene Quantum Dots/β-Ga₂O₃ Solar-Blind Photodetector with Enhanced Photoresponsivity

The superior optical and electronic characteristics of quasi-two-dimensional β-Ga₂O₃ make it suitable for solar-blind (200-280 nm) photodetectors (PDs). The metal-semiconductor-metal (MSM) PDs commonly suffer from low photoresponsivity, slow response speed, and a narrow detection wavelength range despite their simple fabrication process. Herein, we report a high-performance MSM PD by integrating exfoliated β-Ga₂O₃ flakes with zero-dimensional graphene quantum dots (GQDs), which exhibits the advantages of enhancing the photoresponsivity, shortening the photoresponse time, and stimulating a broad range of photon detection. The hybrid GQDs/β-Ga₂O₃ heterostructure PD is sensitive to deep-ultraviolet (DUV) light (250 nm) with an ultrahigh responsivity (R of ∼2.4 × 10⁵ A/W), a large detectivity (D* of ∼4.3 × 10¹³ Jones), an excellent external quantum efficiency (EQE of ∼1.2 × 10⁸%), and a fast photoresponse (150 ms), which is superior to the bare β-Ga₂O₃ PD. These improvements result from effective charge transfer due to the introduction of GQDs, which enhance the light absorption and the generation of electron-hole pairs. In addition, the hybrid GQDs/β-Ga₂O₃ PD also exhibits better photoelectric performance than the bare β-Ga₂O₃ PD at a 1000 nm wavelength. As a conclusion, the hybrid GQDs/β-Ga₂O₃ DUV photodetector shows potential applications in commercial optoelectronic products and provides an alternative solution for the design and preparation of high-performance photodetectors.