Ultrasensitive Deep‐Ultraviolet Photodetectors Based On Band Engineering and Ferroelectric Modulation

Abstract Wide bandgap semiconductors have emerged as a class of deep‐ultraviolet sensitive materials, showing great potentials for next‐generation integrated devices. Yet, to achieve a high photoresponse of deep‐ultraviolet detector without complicated designs at low supply voltage and weak light intensity is challenging. Herein, a new way is designed to fabricate an ultrasensitive vertical‐structured photodetector with epitaxial 7 nm BaTiO 3 interlayer and 10 nm Ga 2 O 3 photosensitive layer, realizing the detection to a rare weak deep UV light intensity (0.1 µW cm − 2 ) at a voltage under 4.8 V and demonstrating a surge in responsivity up to 1.1 A W −1 with ultrafast response of 0.24 µs/33.4 µs (rise/decay). A responsivity of 3.8 mA W −1 at 0 V also has been reached. The dark current is suppressed by enlarged conduction band offset and meanwhile the photocurrent is enhanced by unidirectional conducting valance band offset, which formed by BaTiO 3 interlayer. BaTiO 3 also contributes most to the photoresponse at 0 V through its ferroelectric depolarization electric field. These results provide a path toward high‐sensitive, low‐power‐consumption, and highly‐integrated deep‐ultraviolet detection, beyond conventional ones.