Development of Small-Sized Scanning Tunneling Microscope with Auger-Electron Analyzer

在这项研究中，我们开发了一种新型的小型表面分析仪，它包括两个重要而不可或缺的表面分析和观察功能：俄歇元素分析和扫描隧道显微镜(STM)。为了制作这样的分析器，我们在STM设备的基础上提出了一种特殊的STM针尖作为激发表面核心电子的电子源，以及一种用于表面发射俄歇电子的能量分析器。事实上，我们已经设计和生产了这样一个系统。对于特殊的尖端，我们利用电子轨道分析、聚焦离子束装置等软件程序，经过反复的计算和尖端试验，成功地制备出具有屏蔽功能(以及Wehnelt函数)的尖端，可以消除尖端偏压形成的强电场的影响(通常的问题)。对于电子能量分析仪，由于其在信噪比方面的优势，采用了柱面镜式，而不是延迟栅格式。利用位于特殊针尖后面的柱面反射镜分析器，我们证实了样品表面的俄歇电子可以在准确的动能下被探测到。此外，我们还证实了STM本身的原子分辨率。此外，通过计算，我们还发现了在尖端附近增加透镜电极对俄歇电子能谱空间分辨率的提高。根据这些结果，我们成功地研制出了“带俄歇电子分析器的小型扫描隧道显微镜”的原型系统。

In this research we have developed a new-type small-sized surface analyzer which includes two important and indispensable functions for surface analysis and observation : Auger element analysis and scanning tunneling microscopy (STM). To produce such an analyzer, we have proposed a special STM tip working as an electron source for the excitation of core electrons at the surface, with an energy analyzer for Auger electrons emitted from the surface, on the basis of an STM equipment. Actually we have designed and produced such a system. For the special tip, we have succeeded to prepare the tip with the shield function (and also the Wehnelt function) which can eliminate the effect of the strong electric field formed by the tip bias-voltage (the usual problem), after the repetition of calculations and tip-trials using software programs for the electron orbital analysis, the focused ion beam facility, and so on. For the electron energy analyzer, the cylindrical-mirror type was adopted because of the advantage in the signal-to-noise ratio rather than the retardation-grid type. Using the cylindrical-mirror analyzer located behind the special tip we confirmed that Auger electrons from sample surfaces can be detected at the accurate kinetic energies. Moreover, we also confirmed the atomic resolution of the STM itself. Furthermore, we found the progress of the spatial resolution for the Auger electron spectroscopy by the addition of the lens electrode around the tip using the calculation. From these results, we have succeeded to develop a prototype system of "the small-sized scanning tunneling microscope with Auger-electron analyzer".