【Domestic Papers】Realization of high-performance solar-blind UV detector via a ZrO₂/Ga₂O₃/LaOₓ p-i-n heterostructure

      Researchers from Chongqing University of Arts and Sciences, Tomsk Polytechnic University, SPIC Yuanda Environmental-Protection Engineering Co., Ltd have published a dissertation titled "Realization of high-performance solar-blind UV detector via a ZrO₂/Ga₂O₃/LaOₓ p-i-n heterostructure" in Optics Express.

Background

      Solar-blind UV ranges from 200–280 nm and is largely absorbed by atmospheric ozone, eliminating solar background noise for ground detection. Such technology is widely required in missile warning, power equipment partial discharge inspection and industrial flame monitoring. β‑Ga₂O₃ with a ~4.9 eV intrinsic bandgap inherently matches solar-blind spectrum without optical filters and serves as core optoelectronic material. Conventional interdigital β‑Ga₂O₃ photodetectors suffer low photon utilization from metal shading and second-scale response restricted by carrier recombination, failing fast transient UV measurement. Common heterojunction partners like ZnO and NiO have narrow bandgaps causing undesirable long-wave UV response, while ultra-wide-band Al₂O₃ shows poor conductivity. Few all-solution-processed p-i-n trilayer heterostructures with pure solar-blind property have been explored, leaving evident research gaps in device architecture development.

Abstract

      Solar-blind ultraviolet (UV) detection, operating in the 200-280 nm wavelength range, is of critical importance for applications such as missile warning and secure communication due to the inherent absence of solar background radiation. While β-Ga₂O₃ is a promising material for inherent solar-blind detection, conventional photoconductive detectors based on it suffer from low responsivity and slow response. This work presents a self-powered, vertical heterojunction solar-blind photodetector designed to overcome these limitations. The device features an innovative n-ZrO₂/β-Ga₂O₃/p-LaOₓ ternary thin-film structure that forms a p-i-n junction with nearly ideal band alignment, creating a strong built-in electric field for efficient carrier separation. A high-transmittance silver nanowire (AgNWs) network serves as the top window electrode, enabling high photon flux. The fabricated detector operates at 0 V bias, achieving a responsivity of 5.2 mA W⁻¹, a specific detectivity (D*) of 2.59 ×10¹² Jones, and a photo-to-dark current ratio exceeding 4.1 ×10⁴ under 254 nm illumination. Furthermore, the response speed is significantly enhanced, with 0.36/0.58 s under lower illumination (20 μW cm⁻²) and 56/150 ms under higher intensity (350 μW cm⁻²). The detector’s exceptional performance was further validated through a solar-blind UV imaging system, where it successfully reconstructed clear patterns with high contrast and a clean background, demonstrating its potential for practical imaging applications. This work provides a novel device architecture for high-performance, self-powered solar-blind photodetection and offers valuable insights for the design of wide-bandgap semiconductor optoelectronic devices.

Highlights

      Adopts full-solution spin-coating technology to prepare ZrO₂/β-Ga₂O₃/LaOₓ p-i-n vertical heterojunction photodetector without vacuum equipment.

      All functional layers possess ultra-wide bandgap to realize intrinsic pure solar-blind response without auxiliary optical filter.

      Introduce high-transmittance AgNWs as top window electrode to improve effective incident photon quantity greatly.

      The obtained device obtains D* of 2.59 ×10¹² Jones and realizes clear solar-blind pattern imaging.

Conclusion

      Overall, we have successfully developed a high-performance, self-powered solar-blind UV photodetector based on a solution-processed n-ZrO₂/β-Ga₂O₃/p-LaOₓ vertical heterojunction. This design effectively overcomes two major drawbacks of conventional β-Ga₂O₃ photoconductive detectors: low photon utilization and slow response. The key advances of this work are fourfold. (1) The device features a novel p-i-n heterojunction entirely composed of wide-bandgap materials (ZrO₂, β-Ga₂O₃, LaOₓ), which provides inherent solar-blind spectral selectivity without requiring external optical filters. (2) The nearly ideal band alignment and strong built-in electric field enable efficient separation and extraction of photogenerated carriers. (3) A highly transparent silver nanowire (AgNWs) electrode (>80% transmittance in the solar-blind region) ensures sufficient photon flux for high responsivity and detectivity. (4) The detector exhibits outstanding overall performance, including a detectivity of 2.59 ×10¹² Jones in self-powered mode, a photo-to-dark current ratio >10⁴, and excellent long-term stability. Its clear UV imaging capability further confirms practical applicability. This study not only proposes a promising device architecture for next-generation solar-blind detection, but also demonstrates the effectiveness of bandgap and heterojunction engineering in enhancing wide-bandgap optoelectronics. Furthermore, the all-solution, vacuum-free fabrication method offers a cost-effective route toward scalable device production.

Project Support

      This work was supported by National Key R&D Program of China (Grant No. 2022YFB3603202); National Natural Science Foundation of China (Grant No. 62171069); Natural Science Foundation of Chongqing (CSTB2024NSCQ-LZX0009, CSTB2024TIAD-KPX0004, CSTB2023NSCQ-LZX0058, CSTB2023TIAD-KPX0022); Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJQN202301315).