基于微区扫描光电流谱技术的微纳光电器件表面和界面特性研究

Micro- and Nano-photoelectric devices based on nanomaterials offer several advantages, such as small, light and sensitive to electromagnetic interaction, which will be one of the most important research field for realizing high performance photodetector. While the high ratio surface area and high surface activity make devices performance depends on the properties of surface and interface. Therefore, in order to understand the intrinsic photoresponse mechanism and carrier transport properties, we should research the photoelectric properties of surface and interface. This research project aims to research the properties of surface and interface in Micro- and Nano-photoelectric devices based on carbon nanotube, graphene and black phosphorus using scanning photocurrent microscopy (SPCM). SPCM will show local photoresponse, photo-generated carrier transport properties and dynamic. Based on these research, we expect to understand the intrinsic photoresponse mechanism, the carrier transport properties through interface and the coupling between the photo-generated carrier from nanomaterial and the electron in electrode. Our research will provide theoretical and technical bases for developing high performance Micro- and Nano-photodetector.

基于纳米材料的微纳光电器件具有体积小、质量轻、对电磁相互作用敏感等特点，是未来高性能光电探测器研究的主要方向之一。但同时，纳米材料具有比表面积大、表面活性高等特点，器件性能受表面和界面特性的影响大，导致对器件光电转换机理、光生载流子传输特性理解不清楚。因此本项目采用微区扫描光电流谱技术，分别以碳纳米管、石墨烯、黑磷为代表，从空间分辨和时间分辨两个方面，系统的研究基于这些纳米材料的器件表面局域光电转换特性、及光生载流子在不同界面的传输特性，从微观尺度揭示器件的光电转换机理、光生载流子传输特性及低维纳米材料中的光生载流子与电极中电子的耦合特性，从而为开发高性能的微纳光电探测器提供理论指导和技术支持。

纳米材料的表面和界面特性研究一直都是该领域研究的重点和热点，在本项目资助和牵引下，我们首先搭建了一套超快微区光谱及光电流谱测试系统，该系统波长范围覆盖了240nm~15μm、时间分辨率小于200fs（部分波段可以到50fs）、空间分辨率达到μm量级、样品温度可调范围在4.5K~475K；研究了基于碳纳米管、石墨烯、黑磷和MoTe2的器件中材料与金属界面和表面特性对器件性能的影响，发现了碳纳米管中的超快响应特性、垂直石墨烯器件中的载流子倍增效应；揭示了纳米材料和金属的界面电学表现欧姆接而光电表现肖特基特性的物理机理、大气中水和氧气对纳米材料导电极性的修饰机理；实现了MoTe2器件导电极性的可控调节、基于WSe2/In2O3和WSe2/ZnO异质结的高性能光电探测器件原型。该研究为后续开发基于纳米材料及其异质结器件奠定了基础，尤其是提供了开发超高灵敏度异质结红外探测器的基础，这在国防安全和航天遥感方面都有很大的应用需求和应用前景。