Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871, Japan.
J Phys Condens Matter. 2011 Oct 5;23(39):394202. doi: 10.1088/0953-8984/23/39/394202. Epub 2011 Sep 15.
Atomic arrangements of Si(001), Si(110) and 4H-SiC(0001) surfaces after wet-chemical preparations are investigated with scanning tunneling microscopy. Their passivated structures as well as the surface formation mechanisms in aqueous solutions are discussed. On both Si(001) and Si(110) surfaces, simple 1 × 1 phases terminated by H atoms are clearly resolved after dilute HF dipping. Subsequent etching with water produces the surfaces with 'near-atomic' smoothness. The mechanisms of atomic-scale preferential etching in water are described in detail together with first-principles calculations. Furthermore, 4H-SiC(0001), which is a hard material and where it is difficult to control the surface structure by solutions, is flattened on the atomic scale with Pt as a catalyst in HF solution. After a mechanism is proposed based on electroless oxidation, the flattened surface mainly composed of a 1 × 1 phase is analyzed. The obtained results will be helpful from various scientific and technological viewpoints.
采用扫描隧道显微镜研究了化学湿法处理后 Si(001)、Si(110)和 4H-SiC(0001)表面的原子排列。讨论了它们的钝化结构以及在水溶液中的表面形成机制。在 Si(001)和 Si(110)表面，经稀 HF 浸泡后，很容易分辨出简单的由 H 原子终止的 1×1 相。随后用去离子水刻蚀可得到具有“近原子”平整度的表面。详细描述了水在原子尺度上优先刻蚀的机制，并结合第一性原理计算进行了讨论。此外，在 HF 溶液中使用 Pt 作为催化剂，对于难以通过溶液控制表面结构的硬质材料 4H-SiC(0001)，可以在原子尺度上进行平坦化处理。在提出基于化学镀氧化的机制后，对主要由 1×1 相组成的平坦化表面进行了分析。获得的结果将从各种科学和技术角度提供帮助。
