Comprehensive Study on Ultra-Wide Band Gap La₂O₃/ε-Ga₂O₃ p–n Heterojunction Self-Powered Deep-UV Photodiodes for Flame Sensing

Abstract

Solar-blind UV photodetectors have outstanding reliability and sensitivity in flame detection without interference from other signals and response quickly. Herein, we fabricated a solar-blind UV photodetector based on a La₂O₃/ε-Ga₂O₃ p-n heterojunction with a typical type-II band alignment. Benefiting from the photovoltaic effect formed by the space charge region across the junction interface, the photodetector exhibited a self-powered photocurrent of 1.4 nA at zero bias. Besides, this photodetector demonstrated excellent photo-to-dark current ratio of 2.68 × 10⁴ under 254 nm UV light illumination and at a bias of 5 V, and a high specific detectivity of 2.31 × 10¹¹ Jones and large responsivity of 1.67 mA/W were achieved. Importantly, the La₂O₃/ε-Ga₂O₃ heterojunction photodetector can rapidly respond to flames in milliseconds without any applied biases. Based on the performances described above, this novel La₂O₃/ε-Ga₂O₃ heterojunction is expected to be a candidate for future energy-efficient fire detection.