【Member Papers】High Performance α-Ga₂O₃ Deep Ultraviolet Photodetector Grown by Mist-CVD

      Researchers from the Nanjing University of Posts and Telecommunications have published a dissertation titled "High Performance α-Ga₂O₃ Deep Ultraviolet Photodetector Grown by Mist-CVD" in IEEE Photonics Technology Letters.

Project Support

      This work was supported by the National Natural Science Foundation of China under Grant 62304113, 62204126, 62334003 and U23B2042.

Background

      Deep-ultraviolet (DUV) photodetectors are critical for applications such as flame detection, space communication, missile warning, and environmental monitoring, requiring solar-blind operation. Among wide-bandgap semiconductors, metastable α-Ga₂O₃ is a promising candidate due to its ultra-wide bandgap (~5.2 eV), excellent thermal stability, and high breakdown field. Mist chemical vapor deposition (mist-CVD) enables low-cost, scalable growth of high-quality α-Ga₂O₃ thin films, yet previous devices often suffer from low responsivity or long response times due to material and interface defects. Recent studies demonstrate that mist-CVD-grown α-Ga₂O₃ metal–semiconductor–metal photodetectors can achieve kilovolt-ampere-per-watt-level responsivity with millisecond-scale response times, highlighting the potential of this approach for high-performance DUV photodetectors.

Abstract

      In this letter, we report the fabrication and characterization of a metal–semiconductor–metal (MSM) deep-ultraviolet (DUV) photodetector based on α-Ga₂O₃ thin films grown by mist chemical vapor deposition (mist-CVD). The α-Ga₂O₃ films exhibit excellent crystallinity and surface uniformity, enabling the realization of high-performance DUV photodetectors. The fabricated device achieves an ultra-high responsivity exceeding 1000 A/W at 210 nm, an ultra-low dark current of 0.12 pA at 5 V, and a high UV-to-visible rejection ratio of ~10⁵. In addition, a temporal response with a decay time of millisecond scale is observed. These results demonstrate the viability of mist-CVD-grown α-Ga₂O₃ for scalable and cost-effective fabrication of next-generation DUV optoelectronic devices.

Conclusion

      In summary, a high-performance DUV PD based on α-Ga₂O₃ thin films grown by mist-CVD has been demonstrated. The epitaxial α-Ga₂O₃ film exhibits excellent crystalline quality, wide optical bandgap (5.28 eV), and smooth surface morphology. The resulting MSM PD achieves a peak responsivity exceeding 1000 A/W at 210 nm, ultra-low dark current (~0.12 pA), a high UV-to-visible rejection ratio (~10⁵), and decay times below 100 ms. The device also exhibits robust cycling stability, maintaining consistent performance across repeated switching. These results confirm that mist-CVD is a viable, scalable, and low-cost route for fabricating high-performance DUV PDs.