Ultrasensitive Deep-Ultraviolet Photodetectors Based On Band Engineering and Ferroelectric Modulation.

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 interlayer and 10 nm GaO photosensitive layer, realizing the detection to a rare weak deep UV light intensity (0.1 µW cm ) at a voltage under 4.8 V and demonstrating a surge in responsivity up to 1.1 A W with ultrafast response of 0.24 µs/33.4 µs (rise/decay). A responsivity of 3.8 mA W 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 interlayer. BaTiO 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.