[Sep 9, 2016] 강명호 교수 연구실 - Single-Layer Limit of Metallic Indium Overl…

Density-functional calculations are used to identify one-atom-thick metallic In phases grown on the Si(111) surface, which have long been sought in quest of the ultimate two-dimensional (2D) limit of metallic properties. We predict two metastable single-layer In phases, one 7‾√×3‾√ phase with a coverage of 1.4 monolayer (ML; here 1 ML refers to one In atom per top Si atom) and the other 7‾√×7‾√ phase with 1.43 ML, which indeed agree with experimental evidences. Both phases reveal quasi-1D arrangements of protruded In atoms, leading to 2D-metallic but anisotropic band structures and Fermi surfaces. This directional feature contrasts with the free-electron-like In-overlayer properties that are known to persist up to the double-layer thickness, implying that the ultimate 2D limit of In overlayers may have been achieved in previous studies of double-layer In phases.