Woo Jeongseok, Shim Hyungjoon, Lee Geunseop
Department of Physics, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, Republic of Korea.
J Phys Condens Matter. 2019 Nov 20;31(46):465001. doi: 10.1088/1361-648X/ab33c9. Epub 2019 Jul 19.
Using a scanning tunneling microscope (STM), we demonstrate that the In-induced hexagonal (√7 × √3-hex) and rectangular (√7 × √3-rect) √7 × √3 phases on Si(111) are from the same surface with a double layer of In. The double-layer In thickness was derived from observations that a √7 × √3-hex island was formed on the √7 × √3-'striped' phase, which is believed to have a single layer of In atoms. Bias-dependent STM images were obtained from the same √7 × √3 domain and exhibited both √7 × √3-hex and √7 × √3-rect features, which led to the conclusion that both √7 × √3 STM features originate from the same structure. These findings are in stark contrast to the prevailing idea that there are two √7 × √3 surfaces with different structures and In coverage. We also observed a long-range Moiré-like superstructure in the √7 × √3 surface and attribute it to the mismatch of the lattices of the surface layer of In and the Si(1 1 1) substrate.
使用扫描隧道显微镜（STM），我们证明了在Si(111)上In诱导的六角形（√7×√3 - hex）和矩形（√7×√3 - rect）√7×√3相来自具有双层In的同一表面。双层In的厚度是通过观察到在√7×√3 - “条纹”相上形成了一个√7×√3 - hex岛而得出的，据信该“条纹”相具有单层In原子。从同一√7×√3畴获得了与偏压相关的STM图像，其同时展现出√7×√3 - hex和√7×√3 - rect特征，这导致得出结论：两种√7×√3 STM特征源自相同的结构。这些发现与普遍观点形成鲜明对比，普遍观点认为存在两种具有不同结构和In覆盖度的√7×√3表面。我们还在√7×√3表面观察到了一种长程类莫尔超结构，并将其归因于In表面层与Si(1 1 1)衬底的晶格失配。
