【Domestic Papers】A wide ultraviolet spectra response photodetector based on epitaxial growth of highly-oriented ε-Ga₂O₃ crystal on diamond substrate

      Researchers from the Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, PR China have published a dissertation titled " A wide ultraviolet spectra response photodetector based on epitaxial growth of highly-oriented ε-Ga₂O₃ crystal on diamond substrate " in Functional DiamonD.

Abstract

      In recent years, diamond has shown great potential in solar-blind ultraviolet (UV) photodetection due to its ultrawide bandgap (∼ 5.5 eV) and other superior semiconductor properties. However, the response region of diamond photodetector is usually smaller than 230 nm, which cannot cover the whole solar-blind region from 200 to 280 nm. In this work, an ε-Ga₂O₃/diamond photodetector with wide spectra responsivity from 210 (or even lower) to 260 nm was fabricated. High-quality ε-Ga₂O₃ film with columnar crystal was epitaxially grown on single crystalline CVD diamond substrate by pulse laser deposition (PLD). TEM characterization revealed that the ε-Ga₂O₃ film grew along the <001> orientation on diamond (100) substrate. The deep ultraviolet (DUV) photodetector based on the ε-Ga₂O₃/diamond structure showed a high light-to-dark ratio over 5.7 × 10⁴ and good linear response to the incident light power density from 10 to 400 mW/cm². Moreover, compared to other photodetectors, the fabricated ε-Ga₂O₃/diamond photodetector achieved high responsivity and wide spectra response region from 210 to 260 nm, with high solar-blind rejection ratio of 104 (R₂₄₀/R₂₈₀) and 165 (R₂₁₀/R₂₈₀), respectively. The extension of spectra region with high responsivity of the ε-Ga₂O₃/diamond photodetector can be attributed to the thin thickness of ε-Ga₂O₃ film (around 200 nm) and parts of the DUV light were absorbed by diamond. The high responsivity and wide spectra response region indicate the fabricated ε-Ga₂O₃/diamond photodetector can be used for the detection of ultraviolet in the most of the DUV region.

Paper Link：https://doi.org/10.1080/26941112.2023.2256360