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

通过能量过滤RHEED方法，阐明了弹性和非弹性散射电子构成RHEED图的几个方面。1.从常规RHEED图案中去除非弹性散射分量，由于背景强度降低和菊池线消失，衍射图案的对比度变得更高。(1)对于Si（001）2xl表面，从背景中清晰地提取出了由c（4x 2）结构无序化产生的孤斑图。(2)对于邻位Si（111）7 × 7表面，在零损耗RHEED图案中发现了在穿过镜面斑点的垂直线中的一些额外斑点。结果表明，这些额外的斑点可以解释为一个规则的台阶表面。(3)对于Si（111）上Al的γ相结构，从零损耗图案运动学分析表面结构为9 × 9无公度结构。2.为了研究非弹性散射电子的能量损失， 关于我们 对几种衍射光束、菊池线和背景进行了光谱测量。结果表明，RHEED光束会产生强烈的表面等离子体激元损失，且损失的大小与入射光束的掠射角和衍射光束的出射角有关。3.结果发现，传统的摇摆曲线不同于零损耗的相对强度。低角侧的峰的相对强度随着去除非弹性分量而减小。这意味着更多的掠射电子束以更高的概率遭受表面等离子体激元损失。在摇摆曲线的动力学计算中，通过引入向真空方向扩展的虚势，可以唯象地处理这种峰强度的降低。4.在研究RHEED振荡机理的基础上，首先考察了室温下Al在Si（111）7 x7和Si（111）3x 3-Al两种不同衬底上生长模式的差异。结果表明，Al在7 × 7表面上沉积呈岛状生长，而在3 × 3-Al表面上沉积呈层状生长，但不完全。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