【Domestic Papers】High-grade β-Ga₂O₃ VUV Photodiodes Achieving 131 dB Linear Dynamic Range for 50-200 nm Beamline Applications

      Researchers from the Fuzhou University have published a dissertation titled "High-grade β-Ga₂O₃ VUV Photodiodes Achieving 131 dB Linear Dynamic Range for 50-200 nm Beamline Applications" in IEEE Electron Device Letters.

Background

      Advanced vacuum ultraviolet (VUV) light sources—such as synchrotron radiation (SR, 40–200 nm) and free-electron lasers (FEL, 50–150 nm)—serve as indispensable tools for probing electronic structures and ultrafast dynamics in fundamental research. In situ deployment of photodetectors (PDs) across multiple stations is essential to monitor photon flux dynamically. These PDs require large active areas (exceeding beam profiles), broad linear dynamic range (LDR), and fast response speeds for precise dose quantification. As the prevailing standard detectors, Si-based PDs face rapid responsivity degradation and lattice damage, creating urgent demand for next-generation photodetector solutions. Belonging to the fourth-generation semiconductors, β-Ga₂O₃ (~4.9 eV) emerge as promising alternatives for VUV photodetection, offering high quantum efficiency, inherent radiation hardness and thermal stability.

Project Support

      This work was financially supported by the National Natural Science Foundation of China (62501162), and Fujian Provincial Science and Technology Project (2024J01251, JZ240006). We acknowledge Fujia Co., Ltd. for technical support with the MOCVD process. We thank the staff members of the Metrology Beamline (BL08B) (https://cstr.cn/31131.02.HLS.Metrology) at the Hefei Light Source and the Dalian Coherent Light Source (https://cstr.cn/31127.02.DCLS) for their technical support and assistance in data collection and analysis. 

Abstract

      Advanced vacuum ultraviolet (VUV) light sources serve as indispensable tools for investigating electronic structures and ultrafast dynamics. Here, we report packaged β-Ga₂O₃ photodiodes specifically engineered for VUV beamline monitoring. Through precision-controlled MOCVD epitaxy, we demonstrate high-grade β-Ga₂O₃ film with near-perfect thickness uniformity (99%) and atomically smooth surface, enabling uniform carrier transport across the large active area. The optimized vertical architecture achieves an ultrahigh photo-to-dark current ratio of 7.98×10⁷, a wide linear dynamic range of 131 dB and a nanosecond-scale response time, enabling accurate flux measurements under dynamic beam conditions. Comprehensive spectral characterization from 58-350 nm reveals a peak responsivity of 1.98 A/W at 140 nm (-1 V bias), representing the first complete VUV response profile reported for β-Ga₂O₃ devices. These results establish a new standard for radiation-hard VUV photonics.

Conclusion

      In summary, to address the demand for large-area, wide-dynamic-range, and fast-response detectors for advanced VUV beamline monitoring, this study successfully developed a vertical PD based on a β-Ga₂O₃ thin film. We established a high-grade β-Ga₂O₃ epitaxial growth process, yielding an atomically flat surface and excellent crystallinity. The packaged device demonstrates record-breaking performance in the VUV band, featuring a 131 dB LDR, a nanosecond-scale response and superior stability. These advances reveal β-Ga₂O₃'s unique capabilities to address critical detection challenges in next-generation light sources, lithography, and space applications where conventional detectors fail. In the future, the VUV irradiation dose threshold and irradiation damage mechanism of β-Ga₂O₃ detectors still need to be further systematically studied to promote the real application of such devices in various high-radiation fields.