基于扫描微波显微术的范德瓦尔斯异质结构的电学性质研究

Van der Waals (vdWs) heterostructure — the structure formed by layer-by-layer stacked isolated atomic planes — is one of the hot topics in the world. The electrical properties of vdWs heterostructure are easy to be affected by the interface, such as interfacial adsorption, grain boundaries, ripples and so on.Traditional surface analysis techniques are not sensitive to the buried interface，and the lack of measurement method has restricted the study of the relationship between the interface structure and electrical characteristics of the vdWs heterostructure. This project intends to use a new atomic force microscopy(AFM)—scanning microwave microscopy (SMM) —to study vdWs heterostructure. Combining the advantages of microwave (the penetration and nondestructive detection, etc.) and AFM (high resolution), the technology can simultaneously detect the buried structures and localization electrical properties of various samples.This project intends to use SMM to study the effect of interface roughness, adsorption, grain boundary and superlattice structure on the conductivity and dielectric constant of the vdWs heterostructure, and fine out how to control the localization electrical characteristics of the vdW heterostructure through the interface structure. In addition, by applied a gate voltage on the interface of the vdWs heterostructure, we are also planning to detect the spatial distribution of the conducting channel at the interface and its variation with the gate voltage, understanding the local transport characteristics and the electric field control of devices.

由二维材料堆叠形成的范德瓦尔斯(vdWs)异质结构是目前国际上研究热点之一,其电学性质易受到界面的影响，例如界面吸附物、晶界、褶皱等。传统的表面分析技术对埋藏在表面下的界面并不敏感，测量方法的缺乏制约了对范德瓦尔斯异质结的埋藏界面及其电学特性之间关系的研究。本项目拟采用一种全新的原子力显微术(AFM)——扫描微波显微术(SMM)——对vdWs异质结构进行研究。该技术结合了微波(具有穿透性和无损探测等)和AFM(具有高分辨率)的优势，可探测各种样品的深层结构和局域电学性质。本项目拟利用SMM研究vdWs异质结中埋藏界面处界面粗糙度、吸附物、晶界和超晶格结构对于异质结构的电导率、介电常数等的影响，弄清楚如何通过界面调控异质结构的局域电学性质。此外，我们还将对vdWs异质结构的界面施加门电压，探测器件界面处导电通道的空间分布及其随门电压的变化，深入理解器件工作时局域输运特性及其电场可调控性。

由二维材料堆叠形成的范德瓦尔斯(vdWs)异质结构是目前国际上研究热点之一,其电学性质易受到界面的影响，例如界面吸附物、晶界、褶皱等。传统的表面分析技术对埋藏在表面下的界面并不敏感，测量方法的缺乏制约了对范德瓦尔斯异质结的埋藏界面及其电学特性之间关系的研究。根据计划书，本项目主要利用扫描探针技术研究了二维材料及其异质结构的物性。具体来讲研究了范德瓦尔斯异质结构中，界面偶极、界面电荷转移对于其结构、电学和力学特性的影响；研究了二维材料中晶界对于其局域电学性质的研究；研究了二维材料中应力对于其物性的影响；研究了二维材料中的界面热阻及其影响因素。此外，项目还关注了其他一些国际热点问题。

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