Digital Control of Terrace Width of One-dimensional Semiconductor Surfaces by Modification of Lattice Strain

干净的Si（110）表面呈现出“16x2”的重建，其中一维上下露台交替排列。阶地宽度约为2.5 nm，相邻阶地之间的高度差为1原子层，0.2 nm。该表面是未来低维电子器件和纳米生物材料的有前途的衬底。在这项研究中，我们试图通过一种独特的方法-金属吸附来控制梯田宽度。这是基于表面应力在决定表面阶跃密度方面起作用的想法。我们使用的金属是锡，它和硅属于同一个元素周期表，因为同价掺杂对表面的电子结构影响不大。当Sn在表面吸附0.2 ML时，16x2变为28x2，通过低能电子衍射和扫描隧道显微镜证实了这一点。STM观察表明，锡原子形成三聚体，并相应地插入到硅五边形簇中。结果，降低了地表应力，使梯田宽度扩大到50%左右。此外，从结构的角度出发，我们尝试通过氢终止技术来改变上下梯田的电子性质。结果表明，在反应初始阶段，原子氢与特定的五角形簇原子发生反应，降低了表面应力，并且上下结构保持在氢的饱和覆盖范围内，表明该表面即使在空气中也具有潜力。Ag和Ba在Si（110）上的沉积正在进行中

The clean Si (110) surface shows a "16x2" reconstruction, where one-dimensional up-and-down terraces arrange alternatively. The terrace width is about 2.5 nm and the height difference between the adjacent terraces is one atomic layer, 0.2 nm. This surface is a promising substrate for future low-dimensional electronic devices as well as nano-biomaterials. In this study, we have tried to control the terrace width by a unique method using metal adsorption. This is based on the idea that the surface stress plays a role to determine the surface step density. The metal we used is a tin, which belongs the same periodic table as silicon, because homovalent doping does not so much affect electronic structures on the surface. At 0.2 ML adsorption of Sn on the surface, the 16x2 changed into 28x2, which was confirmed by low-energy electron diffraction as well as scanning tunneling microscopy. STM observation shows that Sn atoms forms trimers which are inserted accordingly into the silicon pentagonal clusters. As a result, surface stress was reduced to make the terrace width being enlarged to about 50%. In addition of structural point of view, we attempted to modify electronic nature of the up-and-down terraces by hydrogen termination technique. The result shows that, at the initial stage of reaction, atomic hydrogen reacts with specific atoms in pentagonal cluster to reduce surface stress, and that the up-and-down structure is kept at a saturation coverage of hydrogen, demonstrating the potential of this surface even in air. Ag and Ba deposition on Si(110) are now in progress