高性能石墨烯/硅量子点中红外光电探测器的探索研究

Communications, imaging, and remote sensing, etc. rely on fast and sensitive photodetectors to convert signals. The unique crystalline and energy-band structure of graphene will play an important role in next-generation high- performance information devices. In this project, in line with the development trend of graphene photodetector, we will carefully consider the thin thickness of graphene/Si-substrate depletion region, and high potential barrier capacitance at their junction, etc.; take the advantage of the weak majority charge-carriers reserving-effect, and the fast reverse-bias recovering-time at graphene/Si- quantum-dots Schottky junction; take the advantage of Schottky barrier to restrain the dark current, thermal excitation at room temperature, and combining the quantum-confinement to enhance signal-to-noise ratio; use the localized surface plasmon resonance of the highly Boron-doped Si-quantum-dots at mid-infrared (3 μm ~ 5 μm) to enhance the light absorption of graphene; bring the fast separation and transport of photo-excited charge-carriers of graphene into play; use both hot carriers multiplication in graphene and avalanche gain in Silicon-substrate to enhance the detectivity; thus break the low speed, narrow operating waveband of the present high-responsive quantum-dots/graphene photodetectors. We will systematically investigate the influence of quantum-dots on the speed and detectivity of graphene photodetector from experiments, and explain its detailed mechanisms. In addition, we will optimize the proposed device structure on the basis above, to fabricate fast and sensitive mid-infrared photodetectors operating at room temperature.

通信、成像、遥感等技术依赖于高速高灵敏的光电探测器转换信号。石墨烯特殊的晶格与能带结构，在新一代高性能信息器件中可发挥重要作用。本项目将根据石墨烯光电探测器的发展趋势，充分考虑到石墨烯硅基耗尽区薄、结区势垒电容大等劣势；利用石墨烯/硅量子点肖特基结多子储存效应小、反向恢复时间快的特点；利用肖特基势垒抑制暗电流、室温热激发，同时结合量子束缚效应提高探测的信噪比；通过硼高掺杂硅量子点在中红外波段(3 μm ~ 5 μm)的表面等离元激发提高石墨烯的光吸收；发挥石墨烯快速分离和输运光生载流子的优势；采用石墨烯热载流子倍增和体硅雪崩增益相结合模式实现探测信号的倍增，突破目前高响应量子点/石墨烯光电探测器低速、响应波段窄的局限。系统的从实验上研究量子点对石墨烯光电探测器响应速度、灵敏度的各种影响，分析并解释其微观机理。在此基础之上设计优化器件结构，实现制备高速高灵敏室温下中红外光电探测的目标。

探索了宏观二维材料红外波段的光与物质相互作用的增强过程，发展了调控二维材料及其异质结中非平衡热载流子的弛豫和收集的方法，形成了若干原创性理论和观点。优化了原型高速高灵敏红外光电探测器件，通过与CMOS光子技术的集成，开发了高分辨红外光子芯片。构建了宏观石墨烯红外宽光谱探测器前端读出集成电路测试平台，建立精确调制的宽光谱光源系统，像素型读出芯片的测试系统、双光子发生脉冲激光单粒子效应测试系统等；新型红外探测器的研制与应用对构建我国太空信息安全，形成快速预警、精确跟踪目标能力，助力构建攻防皆备的空天一体化军事保障体系，具有重要的军事意义和国防价值。基于石墨烯架构的新一代探测器技术及其产品实现将为我国半导体探测器产业及其产品的应用升级带来革命性的技术突破，带来高端工业装备、安全安保领域的技术革命，具有较大的社会价值和经济价值。从基础科学研究角度，聚焦了二维材料红外相机的核心元器件、集成策略等关键技术，以及高效率、低成本图像构建方案，为后续微/小型集成系统演示打好了基础。同时探索并验证了单/少像素成像的构建理论与算法实现以及籍此来实现高效率、极低成本的红外成像与光谱探测技术的可行性。