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Development of a field electron emission-scanning probe microscope with a build-up tip

开发带有构建尖端的场电子发射扫描探针显微镜

基本信息

批准号：
10555008
负责人：
TOMITORI Masahiko
金额：
$ 8.32万
依托单位：
Japan Advanced Institute of Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10555008/
关键词：
field electron emission scanning probe microscope scanning tunneling microscope build-up tip field emission electron spectroscopy

项目摘要

We have developed a new instrument combined with a field electron emission-scanning probe microscope (FEE-SPM) and an electron energy analyzer to acquire energy spectra of electrons backscattered from a sample surface. The sample was irradiated with electrons field-emitted from a build-up [111]-oriented W tip. The area irradiated with the electrons can be imaged by STM with the same tip.In this instrument, the tip fabrication is crucial to draw a stable electron beam. We applied a build-up technique to fabricate it, which is called a thermal-field (T-F) treatment : we apply a positive high voltage to the tip while heating it. The surface atoms on the tip are polarized and pulled toward its apex with a higher electric field, resulting in expansion of some facets with specific plane indices. Consequently, the tip apex is surrounded by a set of facets with vertices and ridges. By choosing the tip axis to a vertex direction, the tip is sharpened : it is the [111] direction for W.An elastic peak with plasmon losses and Auger electron peaks were found for a Si (111) and a Si (111) covered with Ge, and other samples. The Ge islands with 5x5 and 7x7 reconstructions grown on the step and the domain boundaries of the substrate are imaged with the STM.After STM imaging, the tip is retracted slightly and the electron beam is field-emitted from the tip. Several energy peaks are found, which are attributed to plasmons and to Auger electrons of Si LVV and Ge MVV.The Auger peaks shifted toward lower energies as the separation between tip and sample decreases. The electron trajectoriey are possibly deflected in the electric field between tip and sample. A metal plate with a small hole to reduce the electric field was inserted between tip and sample : the peaks became prominent.

我们研制了一种结合场电子发射扫描探针显微镜(FEE-SPM)和电子能量分析仪的新仪器，用于获取样品表面背向散射电子的能谱。用堆积的[111]取向的W针尖发射的电子对样品进行辐照。在该仪器中，针尖的制作是获得稳定电子束的关键。我们应用了一种构建技术来制造它，这被称为热场(T-F)处理：我们在加热的同时向尖端施加正高压。尖端的表面原子被极化，并在较高的电场作用下被拉向尖端，导致某些具有特定平面指数的小面扩展。因此，尖端顶点被一组带有顶点和脊线的小平面包围。通过选择针尖的顶轴方向，尖端被锐化：它是W的[111]方向。在Si(111)和Ge覆盖的Si(111)以及其他样品中，发现了具有等离子体损失的弹性峰和俄歇电子峰。用扫描隧道显微镜(STM)对生长在台阶上的具有5x5和7x7重构的Ge岛和衬底的磁畴边界进行了成像，扫描隧道显微镜成像后，针尖轻微缩回，电子束从针尖出场。发现了几个能量峰，它们分别来自于Si LVV和Ge MV的等离子体激元和俄歇电子，并且随着针尖与样品之间距离的减小，俄歇峰向低能量方向移动。电子轨迹可能在针尖和样品之间的电场中发生偏转。在针尖和样品之间插入一个带有减小电场的小孔的金属板：峰变得突出。