重庆师范大学李万俊教授团队（宽带隙半导体材料与器件团队）在Ga2O3基日盲深紫外光电探测器研究中取得进展。该团队利用高温快速退火实现了异质外延ε-Ga2O3向β-Ga2O3薄膜相变，并研制出高性能β-Ga2O3薄膜基日盲深紫外光电探测器阵列。相关成果以“Boosting the performance of deep-ultraviolet photodetector arrays based on phase-transformed heteroepitaxial β-Ga2O3 films for solar-blind imaging”为题发表在《Science China Technological Sciences》杂志上。团队本科生郑琪琪和陈灵睿为共同第一作者，李万俊教授、叶利娟副教授、张红博士为共同通讯作者。
图像传感器是利用半导体材料的光电效应将光学图像转换成相应的电子信号“图像”的一类光电子器件，其核心是由光电探测器（PDs）构成。日盲紫外光电探测器（SBPD）由于具有低背景信号的天然优势天然适用于UVC图像传感领域的应用。本研究工作，利用高温快速退火将异质外延的亚稳态ε-Ga2O3转变为β-Ga2O3薄膜, 以此提出了通过相转变提高日盲光电探测器阵列性能的新方法。基于相变得到的β-Ga2O3薄膜的金属-半导体-金属型(MSM)日盲光电探测器表现出优异的性能, 其响应率(R)、探测度(D*)、外量子效率(EQE)、抑制比(R254/R365)和开光比(PDCR)分别为459.38 A/W, 1014~1015 Jones, 104~105 %, 105~106和104~106, 并表现出快速的响应速度(1.01 s/0.06 s)和良好的稳定性。值得注意的是, β-Ga2O3薄膜器件的超高响应度比基于ε-Ga2O3 薄膜的器件高出222倍。此外, 组装的β-Ga2O3薄膜基光电探测器阵列(4×5)显示出良好的均匀性、可重复性和空间分辨率。本研究结果为开发用于日盲紫外成像的高性能β-Ga2O3基光电探测器阵列提供了一种有效方法。
Figure 1. (a) Schematic atomic structures of ε-Ga2O3 and β-Ga2O3. (b) X-ray diffraction patterns of Ga2O3 films with phase transition. Tauc plot (c) and SEM images (d-f) of samples S0, S30, and S600.
Figure 2. (a) I-V characteristic curves of ε-Ga2O3 film-based SBPD at 10 V bias voltage; (b) photocurrent and fitting curve; (c) photo-to-dark current ratio and rejection ratio; (d) responsivity and detectivity; (e) EQE; (f) response time; (g) time-dependent light response curve of the device under 254 nm light with different light intensity.
Figure 3. Ga2O3-based SBPDs with varying annealing time: (a) I-V curves; (b) dark current and photocurrent at 365 nm (500 μW/cm2); (c) photocurrent at 254 nm (5, 100, 500 μW/cm2); (d) PDCR and R254/R365; (e) R and D*; (f) EQE; (g) I-t characteristic curve at 254 nm (100 μW/cm2) and (h) response time. For comparison, all properties of the ε-Ga2O3 SBPD were included.
Figure 4. (a) I-V characteristic curves of β-Ga2O3 SBPD (S30) and curves of photocurrent (b), PDCR and R254/R365 (c), R and D* (d), EQE (e), response time (f) and stability versus 254 nm light intensity.
Figure 5. (a) Schematic diagram of solar-blind ultraviolet imaging; current distribution of ε-Ga2O3 SBPD (S0) in (b) dark and (c) 254 nm illumination; current distribution of β-Ga2O3 SBPD (S30) in (d) dark and (e) 254 nm illumination; (f) and (g) correspond to the imaging results of the letter "T" for ε-Ga2O3 and β-Ga2O3 PDAs, respectively.
论文信息：
Qiqi Zheng#(本科生), Lingrui Chen#(本科生), Xudong Li, Ke Ding, Di Pang, Honglin Li, Yuanqiang Xiong, Haibo Ruan, Liang Fang, Wanjun Li*, Lijuan Ye*, Hong Zhang* and Chunyang Kong. Boosting the performance of deep-ultraviolet photodetector arrays based on phase-transformed heteroepitaxial β-Ga2O3 films for solar-blind imaging. SCIENCE CHINA Technological Sciences. 2023, 66: 2707.
论文连接：
https://doi.org/10.1007/s11431-023-2416-6.
