【Domestic Papers】University of Science and Technology Beijing --- Ultrasensitive Deep-Ultraviolet Photodetectors Based On Band Engineering and Ferroelectric Modulation

      Researchers from the University of Science and Technology Beijing have published a dissertation titled "Ultrasensitive Deep-Ultraviolet Photodetectors Based On Band Engineering and Ferroelectric Modulation" in Advanced Materials.

Project Support

      H.W., L.S., and Q.Z. contributed equally to this work. This research was supported by the National Key R&D Program of China (2020YFA0406202), the National Natural Science Foundation of China (22090042, 21971009, and 62204125), Guangxi BaGui Scholars Special Funding, and the Fundamental Research Funds for the Central Universities, China (FRF-IDRYGD21-03 and GJRC003). The authors gratefully acknowledge the cooperation of the beamline scientists at the Beijing Synchrotron Radiation Facility 1W1A beamline. The noise spectrum density was measured by the low-frequency noise test system (LFN-2000), Wuxi Xinjian semiconductor Tech Co,.Ltd.

Background

      Deep-ultraviolet (DUV) photodetectors (PDs) are essential in various fields such as UV imaging, environmental monitoring, military defense, and biological detection. Several wide-bandgap semiconductors, including AlN, ZnO, GaN, and Ga₂O₃, have garnered significant attention for DUV photodetectors. Among these, Ga₂O₃ is a desired candidate on accounts of its suitable direct bandgap of approximately 4.9 eV, high breakdown electric field of around 8 MV cm⁻¹, high absorption coefficient, and thermal stability…

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 BaTiO₃ interlayer and 10 nm Ga₂O₃ 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 BaTiO₃ interlayer. BaTiO₃ 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.

Conclusion

      In summary, we present an ultrasensitive vertical-structured DUV PDs integrated with epitaxial ultrathin BaTiO₃ interlayers and Ga₂O₃ photosensitive layers, meeting the needs of high response, low supply voltage, and highly integrated characteristics in future advanced semiconductor industry. The PD shows high performance with a responsivity value of 1.1 A W⁻¹ at 4.8 V and 0.1 μW cm⁻², 38 mA W⁻¹ at 0 V and 38 μW cm⁻², and ultrafast response of 0.24 μs/33.4 μs (rise/decay). Fine manipulation of energy band and the effect of ferroelectric depolarization electric field realizes such a high photoresponse performance. Hence, this type of DUV PD combined with the integrating compatibility with CMOS in this work offers a promising materials design platform to build future high-sensitive and low-power-consumption Ga₂O₃-based electronic and optoelectronic devices.