SEARCHING FOR THE LAYERED STRUCTURES BY ORDERED SURFACE ALLOYS
Chien-Cheng Kuo1*, Shih-Yu Wu1, Hsin-Lei Chou1, Chia-Hsiu Hsu1, Feng-Chuan Chuang1, Hsin Lin2
1Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2Centre for Advanced 2D Materials and Graphene Research Center, National University of Singapore, Singapore
* presenting author:Chien-Cheng KUO, email:jcckuo@gmail.com
Research exploring the layered structures has become an emergent field after the discovery of graphene and other two-dimensional materials. There is considerable interest in fabricating structures with novel properties and functions based on these layered materials. In this talk I will show some our recent progress on searching for the stable structure of layered materials, by ordered surface alloys. The template we adopted to stabilize the layered structures is Si(111)-α-√3⨉√3-Au which was identified as a good surface for two dimensional electron gas. On this template we show that a stable In layer with higher than expected coverage can be successfully prepared[1]. In additional, bismuth, a much heavier element, was also stabilized on top of the same template[2]. Two thirds of a bismuth monolayer forms a honeycomb structure. This is an experimental evidence of the honeycombed bismuth for the first time. The detailed atomic structure has been verified by both topography and differential conductivity images, and further supported by the density functional theory. Based on the theoretical prediction, the planar honeycombed bismuth is a potential candidate of two-dimensional topological insulator[3], whereas the structure in experiments is tiny buckled, though not far from the predicted one.

Reference
[1] Wu, Shih-Yu, et al. Physical Review B 90 235407 (2014).
[2] Hsin-Lei Chou, Chia-Hsiu Hsu, Shih-Yu Wu, Hsin Lin, Feng-Chuan Chuang, and Chien-Cheng Kuo (unpublished)
[3] Feng-Chuan Chuang, Chia-Hsiu Hsu, Hsin-Lei Chou, Christian P. Crisostomo, Zhi-Quan Huang, Shih-Yu Wu, and Chien-Cheng Kuo, Wang-Chi V. Yeh, Hsin Lin and Arun Bansil (Unpublised).


Keywords: STM/STS, 2D materials, Honeycomb structure