宽光谱、高灵敏石墨烯光电导探测器研究

It is necessary to strengthen the atmospheric environment monitoring in order to counter the prominent air pollution problem. Utilizing the fingerprint of ultraviolet-to-visible optical absorption spectrum of pollution gases such as SO2 and NO2, DOAS (Differential Optical Absorption Spectrum) system can realize precise air pollution monitoring. Highly sensitive photodetector with wide spectrum is one of the key components in DOAS system.Experimental results show that graphene can uniformly absorb 300-2500nm incident. Therefore, graphene photodetectors generally have wide spectrum. In addition, photoconductive photodetectors have extremely high photoresponsivity. Therefore, photoconductive graphene photodetectors hold great potential in wide-spectrum high-sensitivity detection area.A new method to fabricate photoconductive graphene photodetector is proposed in order to simplify the fabrication process and widen the response spectrum. Using the trapping effect originating from inductively coupled plasma etched silicon-on-insulator substrate, photoconductive graphene photodetector with photoresponsivity exceeding 400 A W-1, photoconductive gain higher than 105 and response spectrum from 300 to 900 nm can be realized.The research of this project is significant in the development of DOAS system and atmospheric environment monitoring.

针对日益凸显的空气质量问题，加强大气环境检测是必要的。DOAS系统利用SO2和NO2等在紫外-可见波段的特征吸收谱精准实现污染气体排放检测。其中，宽光谱、高灵敏光电探测器是DOAS系统的核心组件之一。实验研究表明石墨烯材料可均匀吸收300-2500nm入射光，因此石墨烯光电探测器通常具有宽光谱特点，又因为光电导探测器具有极高光响应度，因此石墨烯光电导探测器在宽光谱、高灵敏探测器领域具有巨大潜力。针对传统石墨烯光电导探测器制备方法复杂、响应光谱窄等问题，项目创新地提出一种极其简单的制备石墨烯光电导探测器方法，利用ICP刻蚀SOI衬底陷阱能级对光生载流子的限制作用实现强烈的光电导效应，实现光响应度400 A W-1、光电导增益大于105、响应光谱覆盖300-900 nm的石墨烯光电导探测器。

针对日益凸显的空气质量问题，加强大气环境检测是必要的。DOAS系统利用SO2和NO2等在紫外-可见波段的特征吸收谱精准实现污染气体排放检测。其中，宽光谱、高灵敏光电探测器是DOAS系统的核心组件之一。针对传统石墨烯光电导探测器制备方法复杂的问题，项目对沟道的电场分布进行了有限元仿真，结果显示电场均匀分布在沟道80μm范围内，获得了简易的石墨烯探测器阵列制作方法，实现了2×2光电探测器阵列；项目在电感耦合等离子体刻蚀绝缘硅衬底上研制了石墨烯光电导探测器，阐明了器件的光电导机理来源于衬底的陷阱能级对光生载流子的限制作用，实现光响应度407 A/W、光电导增益2.06×107、响应光谱覆盖300-1550 nm的石墨烯光电导探测器。