One-Step Growth of Amorphous/Crystalline Ga₂O₃ Phase Junctions for High-Performance Solar-Blind Photodetection

The pursuit of high-performance photodetectors functioning in the solar-blind spectrum is motivated by both scientific and practical applications ranging from secure communication, monitoring, sensing, etc. In particular, the fabrication of heterojunctions based on the wide band gap semiconductors has emerged as an attractive strategy to promote the high-efficient photogenerated electron/hole pair separation. However, the precisely controlled growth of heterojunctions remains a huge challenge. The lattice mismatch leads to the formation of defects and/or dislocations at the interface, deteriorating the performance of devices and limiting their envisioned applications. Here, we demonstrate a simple one-step growth of amorphous/crystalline Ga₂O₃ phase junctions by using sputtering technique, yielding a large responsivity of 0.81 A/W, a superior photo-to-dark current ratio over 10⁷, and an ultrahigh response speed of ∼12 ns. Compared to the previous reported solar-blind photodetectors, the obtained detectivity ≈ 5.67 × 10¹⁴ Jones is increased by 2 orders of magnitude. Such excellent photoresponse characteristics can be understood by the interfacial built-in field-promoted electron/hole pair separation for the amorphous/crystalline Ga₂O₃ phase junctions. Our results provide a novel path toward realizing high-performance optoelectronics functioning in the solar-blind spectrum.