Recognition of atomic species on hetero-surfaces by atom resolved tunneling spectroscopy

本研究的目的是提高原子分辨扫描隧道光谱(STS)的重现性，即原子分辨隧道光谱(ARTS)。一般来说，含有各种元素的表面的电子态是由表面上单个原子的特性局部决定的，所以每个原子位上的电子态可能或多或少地引起一些变化。因此，通过扫描隧道显微镜(STM)/扫描隧道显微镜(STS)的仔细检查，有望以原子分辨率识别具有混合成分的样品表面上的原子物种。实现表面原子识别的关键在于尖端的锐度和电子态，因为STS获得的图像容易而严重地被尖端条件改变。在本研究中，我们将[111]取向的W的积层尖端应用于硅和锗工艺。尖端在高温…条件下处理更纯净、更高的电场。经处理后，尖端被三个{112}面包围，然后[111]取向的尖端变得更加尖锐，成为三个面的一角。此外，该处理不仅可以去除尖端的杂质原子，还可以去除尖端小腿上的杂质原子。因此，通过处理可以重现尖端的锐度和电子态。然后，我们对Si(111)7x7的ARTS的重现性进行了论证。利用场发射显微镜观察了实验后针尖尖端的原子变化，并研制了原子力显微镜和电子能量分析仪相结合的新仪器，以探索原子在表面识别的其他可能性。对AFM针尖进行清洗和磨尖处理，并对其进行评估。利用能谱分析仪，我们得到了从堆积针尖出场的电子在Si(111)表面的背散射电子能谱，它显示了体等离激元的损失和SiLV的俄歇峰。这一结果证明了这种组合的新仪器用于原子识别的有效性。较少

The purpose of this study is to improve the reproducibility of scanning tunneling spectroscopy (STS) with an atomic resolution, which is called the atom resolved tunneling spectroscopy (ARTS). Since, in general, the electronic states of surfaces with various elements are locally settled by the characteristics of individual atoms on the surface, some changes in electronic states at each atomic site are possibly induced more or less. Consequently, it is expected that atomic species on sample surfaces with hybrid compositions can be recognized with an atomic resolution by prudent inspection with scanning tunneling microscopy (STM) /STS.The key point to achieve the recognition of surface atoms lies on the sharpness and electronic states at a tip apex, because the images obtained by the STS are altered by the tip conditions, easily and seriously.In this study, we have applied a build-up tip of [111] -oriented W for the ARTS of Si and Ge. The tip was treated under conditions of high temperat … More ure and high electric field. By the treatment the tip apex was surrounded by three {112} facets, and then the apex with the [111] orientation became sharper as a corner of the three facets. Furthermore, the treatment can remove impurity atoms not only from the tip apex, but also from the tip shank. Thus the sharpness and electronic states at tip apex can be reproduced by treatment. Then we have demonstrated the reproducibility of ARTS for Si (111) 7x7. The atomic change of the tip apex after the experiment was inspected by field emission microscope (FEM).Moreover, a new instrument combined with an atomic force microscope (AFM) and an electron energy analyzer has been developed to seek other possibilities of atom recognition on surfaces. The tip for AFM was treated to be cleaned and sharpened, and evaluated. By the energy analyzer, we have obtained backscattered electron energy spectra from the Si (111) surface exited by the field emission electron from the build-up tip, which showed bulk plasmon losses and an Auger peak of Si LVV.This results have demonstrated the availability of the combined new instrument for the atom recognition. Less