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基光电化学型紫外光电探测器阵列及日盲成像研究中取得进展。该团队通过构筑α-Ga2O3@a-Al2O3核壳纳米棒阵列，实现了高性能光电化学型自供电紫外光电探测器阵列，并探索了光电化学型探测器在日盲成像中的应用潜力。相关成果以"Enhancing the Performance of Self-Powered Deep-Ultraviolet Photoelectrochemical Photodetectors Based on a-Ga2O3@a-Al2O3 Core-Shell Nanorod Arrays for Solar-Blind Imaging"为题发表在《Applied Surface Science》杂志上。团队研究生王璇为第一作者，李万俊教授和张红博士为共同通讯作者。
随着Ga2O3基日盲深紫外(DUV)光电探测器(PDs)的发展，将其集成到阵列图像传感器中成为一个热点研究课题。当前，日盲深紫外成像研究主要围绕固态PDs展开，新型光电化学型光电探测器(PEC-PDs)用于日盲成像应用方面仍存在显著的空白。为此，本工作构筑了高性能的α-Ga2O3@a-Al2O3核壳纳米棒阵列(NRAs) PEC-PDs。在DUV辐照和无外加偏压条件下，α-Ga2O3@a-Al2O3器件性能明显优于α-Ga2O3器件。当光强为0.50 mW cm−2时，光电流密度从4.60 μA cm−2显著增加到11.24 μA cm−2，响应率从9.60 mA W−1显著增加到22.70 mA W−1。此外，首次使用5×5矩阵的α-Ga2O3@a-Al2O3核壳NRAs基PEC-PDs来演示自供电日盲成像的概念验证，能够有效地捕捉字母“C”和“N”的形状。
本工作引入了PEC-PDs（光电化学光电探测器）作为成像组件，应用于日盲深紫外光电探测器成像技术中。相较于传统的固态阵列成像技术，PEC-PDs阵列成像展现出以下几项显著优势：
电极制备的简化：传统的固态阵列成像单元需经历复杂的多步骤光刻流程，在已生长的光敏材料上构建电极（每个像素单元至少需求两个电极）。相比之下，PEC-PDs在材料生长前仅需预先布局单一底电极，极大地简化了电极的设计与制备流程。
光敏区域的优化利用：固态阵列成像单元的表面常布满复杂的电极网络，这可能对光敏区域造成显著干扰。而PEC-PDs的电极巧妙地设置于光敏材料的底部，光敏材料直接与电解质接触，从而确保了光敏区域不受电极材料的任何阻碍，实现了更高效的光信号捕获。
成本效益的提升：固态阵列成像器件往往依赖于大量昂贵的贵金属电极。相反，PEC-PDs通常采用成本相对低廉的电极材料，例如FTO（氟掺杂氧化锡）、ITO（铟锡氧化物）、硅等。结合低成本的晶体生长技术，如水热法和水浴法等，PEC-PDs阵列成像技术的整体成本得到了大幅度降低。
Fig. 1. Crystal structure and optoelectronic properties of α-Ga2O3 NRAs. a) Top-view SEM image; b) cross-sectional SEM image; c) XRD diffraction pattern; d) I-V characteristic curve of α-Ga2O3 NRAs UV PEC-type PDs under dark state, 365 nm and 254 nm irradiation; e) I-t response curves under 365 nm and 254 nm illumination; f) I-t response curves at different light intensity.
Fig. 2. Crystal structure properties of α-Ga2O3@a-Al2O3 NRAs. a) Schematic diagram of the preparation process. b) Top-view FE-SEM image, inset is the corresponding cross-sectional FE-SEM image. c) TEM image of a single α-Ga2O3@ a-Al2O3. EDS elemental mapping images of d) O, e) Ga, and f) Al atom. g) The TEM image of an enlarged single α-Ga2O3@ a-Al2O3 nanorods. h) HR-TEM image of α-Ga2O3@ a-Al2O3, the red, blue, and yellow dotted selected areas correspond to the α-Ga2O3, interface, and Al2O3 region, respectively. i) inverse FFT image of α-Ga2O3 region. j) FFT image of α-Ga2O3 region. k) FFT image of the interface. l) FFT image of Al2O3 region. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 3. Photoresponse characteristics of α-Ga2O3 and α-Ga2O3@a-Al2O3 PEC-type PDs. a) I-t curves of α-Ga2O3 and α-Ga2O3@a-Al2O3 (10, 30, 60, and 100 circles) under 254 nm irradiation. b) Response spectra of α-Ga2O3 and α-Ga2O3@a-Al2O3 PEC UV PDs (30 circles) at 0 V. c) The plot of photocurrent density versus light power densities. d) PDCR. e) responsivity (R). f) detectivity (D*). g) Long-time stability tests. h) Comparison of the characterization parameters based on self-powered α-Ga2O3 PEC-type PDs with other α-Ga2O3 based PEC-type photodetectors.
Fig. 4. a) the o 1 s peak and inelastic scattering loss of α-Ga2O3. b) The O 1 s peak and inelastic scattering loss of a-Al2O3 thin film. c) XPS valence band spectrum and Ga 2p core energy level of α-Ga2O3 NRAs. d) XPS valence band spectrum and Al 2p core energy level of a-Al2O3 thin film. e) Al 2p core energy level and Ga 2p core energy level of α-Ga2O3@a-Al2O3. f) Schematic of the energy band arrangement of α-Ga2O3@a-Al2O3. g) The typical self-assembled three-electrode PEC test system for evaluating the photoresponsive behavior of α-Ga2O3 and α-Ga2O3@ a-Al2O3 PEC-type PDs in Na2SO4 electrolyte.
Fig. 5. a) schematic diagram of the device array. b) the actual diagram of the device. c) Photograph of the device after encapsulation. d) Schematic of the solar-blind imaging system. e) Photocurrent density of α-Ga2O3@Al2O3 matrix arrays irradiated in the dark, 100 μA cm− 2 (254 nm and 365 nm) and 400 μA cm− 2 (254 nm) light intensity, respectively. f) and g) are time-resolved photocurrent density of two photoelectrode arrays in the α-Ga2O3@a-Al2O3 PEC PD arrays. h-k) 2D current mapping of the α-Ga2O3@a-Al2O3 PEC PD arrays in the dark state, 365 nm and 254 nm illumination.
论文信息：
Xuan Wang, Ke Ding, Lijuan Huang, Xudong Li, Liyu Ye, Jiangshuai Luo, Jili Jiang, Honglin Li, Yuanqiang Xiong, Lijuan Ye, Di Pang, Yan Tang, Wanjun Li*, Hong Zhang* and Chunyang Kong. Enhancing the Performance of Self-Powered Deep-Ultraviolet Photoelectrochemical Photodetectors by constructing α-Ga2O3@a-Al2O3 Core-Shell Nanorod Arrays for Solar-Blind Imaging. Applied Surface Science, 2024, 648: 159022.
论文链接：
https://doi.org/10.1016/j.apsusc.2023.159022.
重庆师范大学宽禁带半导体材料与器件团队
https://www.x-mol.com/groups/li_wanjun
