基于掺杂硅的高灵敏性超空间分辨太赫兹近场探针的研究

Scanning probe microscope based near-field terahertz microscopy (SNTM) has been employed to investigate semiconductor devices, quantum dots, nanorods and etc., and a resolution as high as several tens of nanometers has been achieved. This techniqe has also shown great potential applications in the fields of nanobiology and nanochemisty. The nanoprobe is the core part of SNTM and the material properties and the radius of curvature of the nanprobe can directly affect the spatial resolution and sensitivity of near-field terahertz imaging. Tradiationally used SNTM nanoprobe has two obvious drawbacks: (1) it is usally composed of metal materials, so the electric field enhancement effect in the terahertz region is very limited, and (2) its radius of curvature is normally larger than 30 nanometers, limited the resolution. As a result, it is difficult to uitilize the tradiationally nanoprobe to achieve high sensitivty and super-resolution near-filed teraheartz imaging for low dielectric properties materials like biological macromolecules (~ 5 nm) and organic matters. The aim of this project is to develope a high sensitivity and super-resolution SNTM nanoprobe by taking the advantage of the plasmon enhanced properties of doped silicon and utilizing a mature micro-nano processing technology. A strong local enhanced electric field in the apex of the doped silicon nanoprobe can be achieved, which is much stronger than than that of a metal nanoprobe. The radius of curvature the doped silicon nanoprobe can be less than 10 nm. Through the implementation of this project, a doped silicon nanoprobe with excellent performance for scanning near-field terahertz microscopy will be manufactured, and the theories related to the interactions between the terahertz wave and semiconductor materials will be develpoed and enriched.

基于扫描探针显微技术的太赫兹近场显微镜对半导体器件、量子点和纳米棒等已实现了纳米级分辨率的成像（几十个纳米），并展现出了在纳米生物科学和纳米化学领域的具大应用前景。纳米探针作为其中最为核心的器件，探针的曲率半径大小、材料等直接影响近场成像的空间分辨率和灵敏度。传统的金属探针对太赫兹波的局域增强性能有限，同时其曲率半径较大（>30 nm），很难对低介电特性的生物大分子（约5 nm）和有机分子实现高灵敏度、高分辨近场成像。本项目拟从掺杂硅在太赫兹波段的局域表面等离子体增强物理特性入手，结合传统微纳加工工艺研发基于掺杂硅材料的具有局域等离子体增强特性的高灵敏性、针尖曲率半径小于10 nm的纳米级空间分辨率的散射式扫描太赫兹近场探针。该探针的成功研制将为扫描近场太赫兹显微技术提供性能优良的核心器件，能发展和丰富太赫兹波与半导体材料相互作用物理理论。

本项目旨在为太赫兹扫描近场显微镜提供必要的器件，为半导体材料对太赫兹波的物理调制机制提供理论支撑，为单个生物大分子及其分子间的相互作用动态过程的实时、高灵敏度、高分辨率的观测提供技术保障。针对以上研究目标，本项目基于FDTD软件，在理论上开展了不同掺杂硅探针和金属纳米探针对太赫兹波的近场局域增强特性和散射特性研究工作；在实验上基于KOH溶液的湿法刻蚀和自锐化方法制备不同掺杂浓度的掺杂硅探针，并结合商用的太赫兹近场扫描显微设备对其近场成像性能进行了检测。基于此探针实现了对CMOS半导体器件和Au/Si开口谐振环超材料样品的太赫兹超分辨检测，并在国际上首次实现了对单个IgG蛋白质分子（约5 nm）、DNA分子的（约2 nm）的太赫兹光谱与成像检测。在相关领域发表文章13篇，申请发明专利4项；基于本项目的研究成果，争取到太赫兹近场超分辨检测方面竞争性项目2项，其中以负责人身份主持项目1项。本项目的成功实施，可望为半导体器件优化和疾病的诊疗提供技术保障，推进我国THz光子学、蛋白质组学等领域的发展。