Ultrahigh Gain Solar Blind Avalanche Photodetector Using an Amorphous Ga₂O₃-Based Heterojunction

Solar blind photodetectors with a cutoff wavelength within the 200-280 nm region is attracting much attention due to their potential civilian and military applications. The avalanche photodetectors (APDs) formed based on wide-bandgap semiconductor Ga₂O₃ are expected to meet emerging technological demands. These devices, however, suffer from limitations associated with the quality of as-grown Ga₂O₃ or the difficulty in alleviating the defects and dislocations. Herein, high-performance APDs incorporating amorphous Ga₂O₃ (a-Ga₂O₃)/ITO heterojunction as the central element have been reliably fabricated at room temperature. The a-Ga₂O₃-based APDs exhibits an ultrahigh responsivity of 5.9 × 10⁴ A/W, specific detectivity of 1.8 × 10¹⁴ Jones, and an external quantum efficiency up to 2.9 × 10⁷% under 254 nm light irradiation at 40 V reverse bias. Notably, the gain could reach 6.8 × 10⁴, indicating the outstanding capability for ultraweak signals detection. The comprehensive superior capabilities of the a-Ga₂O₃-based APDs can be ascribed to the intrinsic carrier transport manners in a-Ga₂O₃ as well as the modified band alignment at the heterojunctions. The trade-off between low processing temperature and superior characteristics of a-Ga₂O₃ promises greater design freedom for realization of wide applications of emerging semiconductor Ga₂O₃ with even better performance since relieving the burden on the integration progress.