Ultrahigh Gain Solar Blind Avalanche Photodetector Using an Amorphous Ga 2 O 3 -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 Ga 2 O 3 are expected to meet emerging technological demands. These devices, however, suffer from limitations associated with the quality of as-grown Ga 2 O 3 or the difficulty in alleviating the defects and dislocations. Herein, high-performance APDs incorporating amorphous Ga 2 O 3 (a-Ga 2 O 3 )/ITO heterojunction as the central element have been reliably fabricated at room temperature. The a-Ga 2 O 3 -based APDs exhibits an ultrahigh responsivity of 5.9 × 10 4 A/W, specific detectivity of 1.8 × 10 14 Jones, and an external quantum efficiency up to 2.9 × 10 7 % under 254 nm light irradiation at 40 V reverse bias. Notably, the gain could reach 6.8 × 10 4, indicating the outstanding capability for ultraweak signals detection. The comprehensive superior capabilities of the a-Ga 2 O 3 -based APDs can be ascribed to the intrinsic carrier transport manners in a-Ga 2 O 3 as well as the modified band alignment at the heterojunctions. The trade-off between low processing temperature and superior characteristics of a-Ga 2 O 3 promises greater design freedom for realization of wide applications of emerging semiconductor Ga 2 O 3 with even better performance since relieving the burden on the integration progress.