Control of the heteroepitaxal growth on vicinal surfaces

在这项研究中，我们瞄准了（i）准备在硅（111）基底上形成一个有机表面， （ii）准备在表面上形成一个金刚石类型的Sn （α-Sn），是与硅相同的第四组，是在一个大的、不匹配的关系中，（iii）稳定地控制其增长形态。在α-Sn/Si（111）的界面上储存弹性应变能量，理论上使用了该作用的关键潜力。这一计算给了我们一个重要的建议，即在Si（111）上采取步骤的有机表面可能会放松有效地在生长的胶片中产生应变能量，并允许在伪病理上生长α-Sn超越临界厚度。在这一结果的基础上，第二，我们实际上是在6嵌入的有机表面上生长的α-Sn，并通过使用反射高能电子干扰（RHEED）和扫描扭曲显微镜（STM）来评估其过程。这些结果如下： RHEED模式显示了用于Vicinal Substrate的地形，其中包括用于该Substrate表面的方向正常，其宽度非常狭窄。从STM观测中，我们获得了在阶梯线和地形上的非统一性信息。将Sn沉积在这样的有机表面上，我们认识到一个Adsorption结构的形成具有√3×√3-R30 °周期。然后，一个特殊的Sn形式是一个α阶段，它导致了包括事实在内的19.5 °（11-2）方向的形成。此外，Sn导致了α到β的阶段变化，最终，整个电影变成了α-Sn，预先刺激从Sn的软弹性的起源.结果表明，使一个有机表面使我们能够稳定地控制大型不匹配系统中的外延生长的电影形态学的结果。

In this study, we aimed (i) to prepare a vicinal surface on the Si(111) substrate, (ii) to grow a diamond type of Sn (α-Sn) on the surface, which is the same IV group to Si and is in a large lattice-mismatched relationship with it, and (iii) to control stably its growth morphology.Prior to our experiments, firstly, elastic-strain energy stored at the interface of α-Sn/Si(111) was calculated theoretically using the Keating potential. This calculation gave us the important suggestion that steps on the Si(111) vicinal surface may relax effectively strain energy in the growing film and allow to grow pseudomorphologically α-Sn beyond a critical thickness. On the basis of this result, secondly, we actually grew α-Sn on the 6゜ -inclined vicinal surface, and assessed its process by using reflection high-energy electron diffraction (RHEED) and scanning turneling microscopy (STM).These results are as follows : RHEED patterns showed that terraces on the vicinal substrate used are inclined against the direction normal to the substrate surface and their widths are very narrow. From the STM observation, we gained information of linearity in the step line and nonuniformity in the terrace. Depositing Sn on such vicinal surfaces, we recognized the formation of an adsorption structure having a √3×√3 -R30゜ period. Then, excess Sn forms an α phase, leading to the formation of a facet inclined 19.5゜ form the [11-2] direction of Si(111). Although further growth of Sn causes a phase change from α to β, finally, the whole film becomes α-Sn, presumably stimming from an origin of soft elasticity of Sn.The results show that the utilization of a vicinal surface enables us to control stably the morphology of epitaxicially grown films in the large lattice-mismatched systems.