A Study of Photoelectron Emission Patterns from the Super-Structures on Semiconductor Surfaces Using a New Electron Energy Analyzer

本研究的主题是利用一种新的显示型球镜分析器来研究半导体表面超结构的光电子发射模式。该分析仪可以显示从样品表面发射的具有一个动能的带电粒子的角分布图。这种分析器的特点是（1）图形不失真，（2）接收锥最终宽（2 π球面度）。1989年，用X射线或同步辐射（SR）测量了芯电子光电子的角分布图形。使用的样品晶体是Si、TaC、W等，吸附质为Ga原子。芯光电子在逸出样品表面时会受到衍射作用，其角分布图包含了样品的结构信息。从而对图案的分析给出了发射原子周围的结构。1990年用He Ⅰ或Ⅱ共振灯测量了价带态光电子的角分布图。在该能量区域的角分布图案示出了电子能带结构的二维图。因此，这项研究可以提供有关能带结构，特别是费米面形状的精确信息。使用的样品是石墨的单晶（Kish石墨）。所得能带结构与文献中的理论和实验结果符合较好。这是日本首次对能带结构进行二维测量，也是世界上第二次。

The subject of this research is the study of the photoelectron emission patterns from the superstructures on semiconductor surfaces using a new display-type spherical mirror analyzer. This analyzer can display the angular distribution pattern of charged particles of one kinetic energy emitted from a sample surface. The characteristics of this analyzer are (1) the pattern is not distorted, (2) the acceptance cone is ultimately wide (2pi steradian).In 1989 the angular distribution pattern of the photoelectrons from core electrons have been measured using X-rays or synchrotron radiations (SR). The sample crystals used were Si, TaC, W etc., and adsorbate was Ga atoms. The angular distribution pattern of core photoelectrons involve structural informations because they suffer from diffraction process when they escape from the sample surface. The analysis of the pattern thereby gives the structure around the emitting atom. Many new patterns have been obtained using SR (ref. 5, 6).In 1990 the angular distribution pattern of the photoelectrons from valence band states have been measured using He I or II resonance lamp. The angular distribution pattern at this energy region shows the 2-dimensional map of the electronic energy band structure. Hence, this study may give precise informations about the band structure especially the shape of the Fermi surface. The sample used was a single crystal of graphite (Kish graphite). The obtained band structure was in good agreement with theory or the experimental ones in the literatures. This result is the first 2-dimensional measurement of the band structure in Japan, and the second one in the world.