摘要：近日，南京邮电大学施政团队以「III-Nitride MQW-based optoelectronic sensors for multifunctional environmental monitoring」¹为题在Chip上发表研究论文，使用收发一体的圆环
近日，南京邮电大学施政团队以「III-Nitride MQW-based optoelectronic sensors for multifunctional environmental monitoring」¹为题在Chip上发表研究论文，使用收发一体的圆环结构多量子阱（MQW）光电传感器，实现对转速、距离和蔗糖浓度等环境参数的检测。第一作者为高绪敏，通讯作者为施政。本文被遴选为本期封面文章和本期Featured in Chip编辑特选文章之一。Chip是全球唯一聚焦芯片类研究的综合性国际期刊，是入选了国家高起点新刊计划的「三类高质量论文」期刊之一。
Chip第3卷第4期（2024年冬季刊）封面
在光子集成芯片的开发中，氮化镓（gallium nitride，GaN）作为第三代半导体材料，因其具备宽带隙、低光吸收率和高电子迁移率等优越的光电性能，成为高度集成光电器件的理想选择2,3。通过将InGaN/GaN多量子阱(Multi-quantum Well，MQW）二极管集成到单一芯片中，开发一种能够同时发光和检测的光电传感器4-6，用于多功能环境监测，展示了其在工业自动化、生物医学诊断和环境监测中的广泛应用潜力。
如图1展示了基于InGaN/GaN MQW的光电子传感器的制造过程和器件结构。该传感器采用同心圆结构设计，包括发光二极管(Light-emitting Diode，LED)和光电探测器(Photodetector，PD)，以优化光捕获效率。
图1 | 同心圆结构的基于MQW的光电传感器的制作过程。左侧和右侧插图分别为芯片的层结构和光镜图。
水平转速检测的原理和装置如图2所示，图2a展示了测试的光学原理，当LED发出光子，经过银镜反射后被PD检测，PD中的电子-空穴对通过光电效应产生的光电流与检测到的光强成正比。如图2b中传感器通过透镜将反射的光聚焦到PD上，匀胶机上安装有一个半圆形的银镜，其反射率约为90%， PD可检测到由于银镜的周期性反射引起的光强度变化，并通过半导体参数分析仪记录和分析光电流的波动频率，从而得到旋转速度。转速从2000 rpm逐渐增加到8000 rpm，光电流的频率随转速的增加而升高，反映出传感器能够精确响应旋转速度的变化。
图2 | 水平转速检测。a，水平转速检测的实验原理。b，测量匀胶机转速的系统装置。c，LED的驱动电流固定为40 mA时，不同转速下的光电流变化。d，匀胶机转速固定为2500 rpm时，在不同的LED驱动电流下测量的PD的光电流曲线。
图3中的实验展示了传感器在垂直运动检测中的应用，研究了传感器对不同垂直距离的光电流响应。通过调整反射镜的运动频率和传感器的LED驱动电流，结果表明光电流响应与运动速度和距离成正相关关系，并保持长期稳定性，同时光电流的变化与检测距离拟合函数呈指数趋势，拟合曲线的相关系数达到R² = 99.776%，为基于光电流的精确距离测量提供了依据，验证了传感器在垂直距离检测中的高灵敏度和稳定性。
图3 | 垂直接近检测。a，垂直接近检测原理图。b，在10 mA的固定驱动电流下，传感器对不同电机速度的响应。c，电机速度固定时，不同的LED驱动电流下测得的光电流变化。d，2000秒内PD的光电流变化。e，15 mA的LED驱动电流下不同距离的动态响应。f，不同距离测量的PD光电流变化的数据拟合。
除此之外，该传感器还可用于蔗糖的浓度检测。与上述实验不同的是，本实验中基于传感器的片内检测机制。如图4a所示，当LED发出的光通过蓝宝石衬底并进入溶液时，光在溶液界面发生反射和折射，反射光被PD捕捉。随着蔗糖浓度的变化，溶液的折射率也随之变化，影响经历全内反射的光量，也即被PD检测到的光强度。通过测量光电流的变化，可以推断溶液的浓度。图4d展示了PD光电流随蔗糖浓度的变化情况，并通过线性拟合得出光电流与浓度之间的关系，相关系数R²达到了99.834%，表明实验数据与拟合结果高度吻合。
图4 | 蔗糖浓度检测。a，蔗糖浓度探测的工作原理。b，蔗糖浓度探测的装置示意图。c，蔗糖溶液的折射率与浓度的函数关系。d，不同浓度的蔗糖溶液中测得的光电流及数据拟合。
综上所述，该传感器凭借其高度集成的设计和多功能检测能力，展现了在多个环境监测应用中的广泛潜力，特别是通过实验验证了其在不同物理量检测中的稳定性和高精度。这项研究为未来多功能光电子传感器的发展奠定了坚实的基础。
III-Nitride MQW-based optoelectronic sensors for multifunctional environmental monitoring¹
In the development of photonic integrated chips, gallium nitride (GaN), as a third-generation semiconductor material, has become an ideal choice for highly integrated optoelectronic devices due to its superior optoelectronic properties, such as wide bandgap, low optical absorption, and high electron mobility2,3. By integrating InGaN/GaN multi-quantum well (MQW) diodes into a single chip, a multifunctional optoelectronic sensor capable of both emission and detection has been developed4-6, demonstrating its broad application potential in industrial automation, biomedical diagnostics, and environmental monitoring.
Fig. 1 | Fabrication process of the MQW-based optoelectronic sensor with two concentric circle structures. The inset on the left and the right is the layer structure and optical image of the fabricated chip, respectively.
As shown in Fig. 1, the manufacturing process and structure of the InGaN/GaN MQW-based optoelectronic sensor are presented. This sensor adopts a concentric circular structure, including a light-emitting diode (LED) and a photodetector (PD), to optimize light-capturing efficiency.
Fig. 2 | Horizontal rotation speed detection. a, The experimental principle of rotation detection. b, Rotation detection system for evaluating the rotational speed of the homogenizer in the horizontal direction. c, Photocurrent variations of the PD with homogenizer at various rotating speeds when the driving current of the LED is fixed at 40 mA. d, Photocurrent profiles of the PD measured with different driving currents of the LED when the rotational speed is fixed at 2500 rpm.
The principle and system for horizontal rotation speed detection are illustrated in Fig. 2. Fig. 2a depicts the optical principle of the experiment: when the LED emits photons, which are reflected by the silver mirror and detected by the PD, the electron-hole pairs in the PD produce a photocurrent through the photoelectric effect which is directly proportional to the intensity of the detected light. As shown in Fig. 2b, the sensor focuses the reflected light onto the PD through a lens, and a half-circular silver mirror with a reflectivity of approximately 90% is mounted on the homogenizer. The PD detects the periodic changes in light intensity caused by the reflection of the silver mirror, and the semiconductor parameter analyzer records and analyzes the frequency of photocurrent fluctuations to determine the rotational speed. As the speed increases from 2000 rpm to 8000 rpm, the frequency of photocurrent also rises, reflecting the sensor's ability to accurately respond to changes in rotational speed.
Fig. 3 | Vertical proximity detection. a, Schematic of the vertical proximity detection. b, The sensor's response to varying motor speeds at a fixed driving current of 10 mA. c, Photocurrent variations of the PD measured with different driving currents of the LED when the motor speed is fixed. d, Photocurrent variations of the PD for 2000 s. e, Dynamic response at varying distances with the LED driven at 15 mA. f, Data fitting of photocurrent variations of the PD measured at varying distances.
The experiment shown in Fig. 3 demonstrates the application of the sensor in vertical motion detection, investigating the photocurrent response of the sensor to different vertical distances. By adjusting the movement frequency of the mirror and the driving current of the LED, the variations in photocurrent were measured. The results show that the photocurrent response is positively correlated with both the speed and the distance, and it maintains long-term stability. Additionally, the changes in photocurrent with respect to the detection distance follow an exponential trend, with a fitting coefficient R² of 99.776%, providing evidence for precise distance measurement based on photocurrent and verifying the sensor's high sensitivity and stability in vertical distance detection.
Fig. 4 | Sucrose concentration detection. a, The working mechanism of the photonic chip with two concentric circle structures. b, The schematic diagram of a device for detecting sucrose concentration using the fabricated chip. c, The refractive index of sucrose solution as a function of its concentration. d, Measured photocurrent of the PD in the sucrose solution with different concentrations.
Moreover, the sensor is also capable of detecting sucrose concentration. Unlike the above experiments, this experiment utilizes the sensor's on-chip detection mechanism. As shown in Fig. 4a, when light emitted by the LED passes through the sapphire substrate and enters the solution, reflection and refraction occur at the interface. The reflected light is captured by the PD. As the sucrose concentration changes, the refractive index of the solution also changes, affecting the amount of light undergoing total internal reflection and subsequently the intensity of light detected by the PD. By measuring the changes in photocurrent, the concentration of the solution can be inferred. Fig. 4d shows the variation of photocurrent with sucrose concentration, and a linear fit reveals a strong correlation (R² = 99.834%) between photocurrent and concentration, indicating a high degree of agreement between the experimental data and the fit.
In conclusion, the sensor, with its highly integrated design and multifunctional detection capabilities, exhibits broad potential in various environmental monitoring applications. The experiments validate its stability and high precision in detecting different physical parameters, laying a solid foundation for the future development of multifunctional optoelectronic sensors.
参考文献
1. Gao, X. et al. III-nitride MQW-based optoelectronic sensors for multifunctional environmental monitoring. Chip3, 100113 (2024).
2. Ryou, J.-H. et al. Control of quantum-confined stark effect in InGaN-based quantum wells. IEEE J. Sel. Top. Quantum Electron. 15, 1080-1091 (2009).
3. Nakamura, S., Mukai, T. M. T. & Senoh, M. S. M. High-power GaN pn junction blue-light-emitting diodes. Jpn. J. Appl. Phys.30, L1998 (1991).
4. Fu, K. et al. Full-duplex visible light communication system using a single channel. Opt. Lett. 47, 4802-5 (2022).
5. Nakazato, H. et al. Micro fluorescent analysis system integrating GaN-light-emitting-diode on a silicon platform. Lab Chip12, 3419-3425 (2012).
6. Shi, Z. et al. Simultaneous dual-functioning InGaN/GaN multiple-quantum-well diode for transferrable optoelectronics. Opt. Mater.72, 20-24 (2017).
论文链接：
作者简介
施政，南京邮电大学通信与信息工程学院副教授，研究生导师，入选首批全国高校黄大年式教师团队。主持国家自然科学面上基金、青年基金、江苏省自然科学青年基金等项目。研究方向主要为无线光通信系统及关键光电子器件。
Zheng Shi, an Assistant Professor and graduate tutor at the School of Communication and Information Engineering, Nanjing University of Posts and Telecommunications, was selected as one of the first Huang Danian-style teacher teams in universities nationwide. He presided projects such as the National Natural Science Foundation of China and Natural Science Foundation of Jiangsu Province of China. His research interests mainly focus on wireless optical communication systems and key optoelectronic devices.
高绪敏，南京邮电大学通信与信息工程学院副教授，研究生导师。主持国家自然科学青年基金、江苏省自然科学青年基金等项目。研究方向主要为III族氮化物材料光电子器件、同质集成可见光通信系统。
Xumin Gao, an Assistant Professor and graduate tutor at the School of Communication and Information Engineering, Nanjing University of Posts and Telecommunications. She presided projects such as the National Natural Science Foundation of China and Natural Science Foundation of Jiangsu Province of China. Her research interests mainly focus on optoelectronic devices of group III nitride materials and homogeneous integrated visible light communication systems.
朱刚毅，南京邮电大学副教授。他于2013年在东南大学电子科学与工程学院获得博士学位。他的主要研究方向是宽带隙半导体微腔的光学和电学特性。
Gangyi Zhu, an Assistant Professor at the Nanjing University of Posts and Telecommunications, China. He received his Ph.D. in 2013 from the School of Electronic Science and Engineering at Southeast University. His primary research focuses on the optical and electrical properties of wide bandgap semiconductor microcavities.
吴冬梅，2023年于南京邮电大学获得学士学位，现为南京邮电大学通信与信息工程学院硕士研究生，主要从事III族氮化物光电子器件方面的研究。
Dongmei Wu, who received her bachelor’s degree from Nanjing University of Posts and Telecommunications in 2023. She is currently a master’s student at the School of Communication and Information Engineering of Nanjing University of Posts and Telecommunications, mainly engaged in the research of III-nitride optoelectronic devices.
关于Chip
Chip（ISSN：2772-2724，CN：31-2189/O4）是全球唯一聚焦芯片类研究的综合性国际期刊，已入选由中国科协、教育部、科技部、中科院等单位联合实施的「中国科技期刊卓越行动计划高起点新刊项目」、「中国科技期刊卓越行动计划二期项目-英文梯队期刊」，为科技部鼓励发表「三类高质量论文」期刊之一。
Chip期刊由上海交通大学出版，联合Elsevier集团全球发行，并与多家国内外知名学术组织展开合作，为学术会议提供高质量交流平台。
Chip秉承创刊理念: All About Chip，聚焦芯片，兼容并包，旨在发表与芯片相关的各科研领域尖端突破性成果，助力未来芯片科技发展。迄今为止，Chip已在其编委会汇集了来自14个国家的69名世界知名专家学者，其中包括多名中外院士及IEEE、ACM、Optica等知名国际学会终身会士（Fellow）。
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