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Measurement Condition on True Atomic Resolution Imaging of Noncontact Atomic Force Microscope

非接触式原子力显微镜真实原子分辨率成像的测量条件

基本信息

批准号：
11450018
负责人：
SUGAWARA Yasuhiro
金额：
$ 8.64万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450018/
关键词：
atomic force microscope atomic force well-defined surface atomic resolution semiconductor surface attractive force dangling bond covalent bond

项目摘要

In this project, we investigated the force interactions between a Si tip and Si(111)√<3>×√<3>-Ag surface, susing noncontact atomic force microscopy (AFM) operating in ultrahigh vacuum (UHV) by using Si and Ag-adsorped tips. By using Si tip, AFM images on Si(111)√<3>×√<3>-Ag surface showed three types of contrasts which depended on the distance between a tip and a sample surface. At the tip-sample distance of about 0.1 -0.3nm, AFM image showed the honeycomb arrangement. At the tip-sample distance of about 0- 0.05nm, the images showed the periodic structure of the triangle consisting of three bright spots with relatively strong contrast. On the other hand, at the distance of 0.05-0.lnm, the image contrast seemed to be the synthesis of the above two types of contrasts. When the tip is far from the sample surface, the tip-sample interaction force is dominated by physical bonding interaction such as the Coulomb force and/or the van der Waals (vdW) force between the tip apex Si atom and Ag trimer on the sample surface. On the other hand, just before the contact, the tip-sample interaction force is dominated by the chemical bonding interaction due to hybridization between the dangling bond out of the tip apex Si atom and the orbit of Si-Ag covalent bond on the surface. By using Ag-adsorbed tip, different image contrast was obtained and no its deitance dependence was observed. For the first time, individual Ag atoms on the surface was observed with atomic resolution. These experimental results suggest that the identification of the atom species is possible by using AFM.

在这个项目中，我们使用非接触原子力显微镜研究了Si针尖与Si(111)√&lt；3&gt；×√&lt；3&gt；-Ag表面之间的力相互作用。使用Si针尖，在Si(111)√&lt；3&gt；×√&lt；3&gt；-Ag表面上的原子力显微镜图像显示出三种类型的对比度，这三种对比度取决于针尖到样品表面的距离。在针尖-样品间距约为0.1-0.3 nm时，AFM图像显示为蜂窝状排列。在针尖-样品距离约0-0.05 nm处，图像显示出由三个对比度较强的亮点组成的三角形的周期性结构。另一方面，在0.05-0.1 nm的距离处，图像对比度似乎是上述两种对比度的综合。当针尖远离样品表面时，针尖-样品相互作用力主要由针尖顶端Si原子与样品表面上的银三聚体之间的库仑力和范德华(VDW)力等物理键合相互作用所决定。另一方面，在接触之前，针尖-样品的相互作用力主要由针尖尖端Si原子的悬挂键与表面的Si-Ag共价键轨道杂化形成的化学键相互作用所决定。利用吸附了银的针尖，获得了不同的图像对比度，并且没有观察到它的电容依赖性。首次用原子分辨率观察到了表面的单个银原子。这些实验结果表明，利用原子力显微镜鉴定原子物种是可能的。