Study of elastic and inelastic scattering electrons in diffraction pattern by energy filtered RHEED observation

利用能量滤波RHEED方法，明确了弹性和非弹性散射电子构造RHEED图的几个方面。1. 从传统的RHEED图中去除非弹性散射成分，由于背景强度的降低和菊池线的消失，衍射图的对比度变得更高。(1)对于Si (001) 2xl表面，可以清晰地从背景中提取出c（4x2）结构无序产生的单一图案。(2)对于相邻的Si (111) 7x7表面，在零损耗RHEED模式中，在穿过镜面光斑的垂直线上发现了一些额外的斑点。结果表明，这些额外的斑点可以用一个规则的台阶表面来解释。(3)对于Al on Si（111）的γ相结构，从零损耗模式出发，运动学分析其表面结构为9 × 9不相称结构。2. 为了研究非弹性散射电子的能量损失、能量损失、能量损失等问题，对几种衍射光束、菊池线和背景进行了光谱测量。研究发现，RHEED光束具有较强的表面等离子体激元损失，表面等离子体激元损失的大小与入射光束的掠射角和衍射光束的发射角有关。3. 研究发现，传统的摇摆曲线与零损耗的摇摆曲线在相对强度上存在差异。随着非弹性分量的去除，低角侧峰的相对强度减小。这意味着更多的掠射电子束以更高的概率遭受表面等离激元损失。提出在振动曲线的动力学计算中，通过引入向真空扩展的虚势，可以从现象学上处理这种峰强度的降低。4. 在研究RHEED振荡机理之初，重点研究了非弹性散射强度，考察了室温下Al在Si (111) 7x7和Si (111) 3x 3-Al两种不同衬底表面上生长方式的差异。发现Al沉积在7x7表面呈岛状生长，而在3x - 3-Al表面呈逐层生长但不完善。少

The following aspects concerning elastic and inelastic scattering electrons constructing a RHEED pattern were made clear by energy filtered RHEED method. 1. Removing the inelastic scattering components from a conventional RHEED pattern, the contrast of the diffraction pattern becomes higher as a result of decreased background intensity and disappearance of Kikuchi lines. (1) For Si (001) 2xl surface, a lone pattern, which is produced by a disordering of the c(4x2) structure, was extracted clearly from the background. (2) For a vicinal Si (111) 7x7 surface, some extra spots in the vertical line across the specular spot were found in the zero-loss RHEED pattern. It was demonstrated that these extra spots can be explained by a regular step surface. (3) For the gamma phase structure of Al on Si (111), the surface structure was kinematically analyzed as 9x9 incommensurate one from the zero-loss pattern. 2. In order to investigate the loss energy of inelastic scattering electrons, energy los … More s spectroscopies were measured for several diffraction beams, Kikuchi line and background. It was found that RHEED beams suffer surface plasmon loss strongly and the magnitude of surface plasmon loss depends on both the glancing angle of incident beam and the take-off angle of the diffraction beam. 3. It was found that a conventional rocking curve differs from the zero-loss one in the relative intensity. The relative intensity of a peak at lower angle side decreases as removing the inelastic components. This means that more grazing electron beam suffers surface plasmon loss with higher probability. It was proposed that such decreased peak intensity can be phenomenologically treated in the dynamical calculation of the rocking curve by introducing an spread imaginary potential toward vacuum. 4. In the beginning of the study on RHEED oscillation mechanism focused on inelastic scattering intensity, the difference of Al growth mode at room temperature on the two different substrates, Si (111) 7x7 and Si (111) 3x 3-Al surfaces, was examined. It was found that Al deposition on 7x7 surface reveals island growth mode, however, that on 3x 3-Al surface layr by layr growth mode but imperfect. Less