【Member Papers】Ultra-wide Dynamic Range 109 dB β-Ga₂O₃ Photodetector Array: Broadest Linear Response from Dim to Bright Light

      Researchers from the Nanjing University of Posts and Telecommunications have published a dissertation titled "Ultra-wide Dynamic Range 109 dB β-Ga₂O₃ Photodetector Array: Broadest Linear Response from Dim to Bright Light" in ACS Photonics.

Project Support

      This work was supported in part by the National Natural Science Foundation of China (grant nos. 62401276, U23B2042), Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (Grant No. NY223161) and in part by the Jiangsu Provincial Key Research and Development Program under Grant BE2022126.

Background

      UV−C (200−280 nm) photodetectors have demonstrated extensive application potential in both military and civilian domains due to their unique spectral response characteristics. These applications include missile tracking, secure communications, fire detection, ozone hole monitoring, chemical/ biological analysis, and solar corona observation. To achieve high-performance UV photodetection, researchers have focused on developing various wide-bandgap semiconductor materials, such as ZnMgO and GaN. Among the various candidate materials, β-Ga₂O₃ stands out due to its exceptional comprehensive performance. Its ultrawide bandgap (4.8−4.9 eV) makes it perfectly suitable for UV−C wavelengths, while also offering high breakdown field, excellent thermal and chemical stability, high UV−visible light transmittance, and superior radiation resistance. Crucially, its unique band structure and carrier transport properties establish a solid physical foundation for achieving wide dynamic range photodetection.

Abstract

      Ultraviolet C (UV–C) band holds significant applications, but current photodetectors are restricted due to their inadequacy in achieving optimal detection performance under both dim and bright illumination conditions. To address these challenges, we have developed an 8 × 8 β-Ga₂O₃ photodetector array that demonstrates superior linearity across an ultrawide dynamic range in the UV–C band, from dim to bright light (40 nW/cm² to 12.2 mW/cm²). This achievement represents the broadest detection range among current integrated array devices. Moreover, our fabricated array exhibits excellent uniformity, with a photocurrent of 1.56 μA (σ = 0.229 μA), all devices conforming to the 3σ distribution. Our device demonstrates superior image processing capabilities, achieving recognition accuracies of 87.27% and 85.55% under dim and bright illumination conditions, respectively. Furthermore, the data set processed utilizing the light intensity-to-photocurrent linearity relationship of our device attained an approximate recognition accuracy of 91%, comparable to that of the original data set. These results signify a notable advancement in UV–C photodetection technology and machine vision applications.

Conclusion

      In this study, we successfully fabricated and demonstrated an 8 × 8 β-Ga₂O₃ array. Comprehensive characterization revealed that the array exhibits excellent uniformity and performance in UV−C band light intensity detection, with an exceptionally wide practical dynamic range from 40 nW/cm² to 12.2 mW/ cm². Compared to previously reported similar devices, our β-Ga₂O₃ array demonstrates superior performance in detecting both extremely weak and high-intensity light signals. Additionally, experimental results indicated a significant linear relationship between the detected light intensity and photocurrent output, providing greater stability and reliability in practical applications than conventional systems prone to over-or under-exposure issues. The β-Ga₂O₃ array maintains stable performance under both strong and weak light conditions, representing a substantial advancement in UV−C detection technology.