Ultra-High Performance Amorphous Ga 2 O 3 Photodetector Arrays for Solar-Blind Imaging.

The growing demand for scalable solar-blind image sensors with remarkable photosensitive properties has stimulated the research on more advanced solar-blind photodetector (SBPD) arrays. In this work, the authors demonstrate ultrahigh-performance metal-semiconductor-metal (MSM) SBPDs based on amorphous (a-) Ga ₂ O ₃ via a post-annealing process. The post-annealed MSM a-Ga ₂ O ₃ SBPDs exhibit superhigh sensitivity of 733 A/W and high response speed of 18 ms, giving a high gain-bandwidth product over 10 ⁴ at 5 V. The SBPDs also show ultrahigh photo-to-dark current ratio of 3.9 × 10 ⁷ . Additionally, the PDs demonstrate super-high specific detectivity of 3.9 × 10 ¹⁶ Jones owing to the extremely low noise down to 3.5 fW Hz ^-1/2 , suggesting high signal-to-noise ratio. Underlying mechanism for such superior photoelectric properties is revealed by Kelvin probe force microscopy and first principles calculation. Furthermore, for the first time, a large-scale, high-uniformity 32 × 32 image sensor array based on the post-annealed a-Ga ₂ O ₃ SBPDs is fabricated. Clear image of target object with high contrast can be obtained thanks to the high sensitivity and uniformity of the array. These results demonstrate the feasibility and practicality of the Ga ₂ O ₃ PDs for applications in solar-blind imaging, environmental monitoring, artificial intelligence and machine vision.
(© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)