Quasi-freestanding, striped WS2 monolayer with an invariable band gap on Au(001)
WS2, Au (001), striped superstructure, interfacial interaction, STM/STS
ABSTRACT Revealing the structural/electronic features and interfacial interactions of monolayer MoS2 and WS2 on metals is essential to evaluating the performance of related devices. In this study, we focused on the atomic-scale features of monolayer WS2 on Au(001) synthesized via chemical vapor deposition. Scanning tunneling microscopy and spectroscopy reveal that the WS2/Au(001) system exhibits a striped superstructure similar to that of MoS2/Au(001) but weaker interfacial interactions, as evidenced by experimental and theoretical investigations. Specifically, the WS2/Au(001) band gap exhibits a relatively intrinsic value of ~2.0 eV. However, the band gap can gradually decrease to ~1.5 eV when the sample annealing temperature increases from ~370 to 720 °C. In addition, the doping level (or Fermi energy) of monolayer WS2/Au(001) varies little over the valley and ridge regions of the striped patterns because of the homogenous distributions of point defects introduced by annealing. Briefly, this work provides an in-depth investigation into the interfacial interactions and electronic properties of monolayer MX2 on metal substrates.
Tsinghua University Press
Min Hong,Xiebo Zhou,Jianping Shi,Yue Qi,Zhepeng Zhang,Qiyi Fang,Yaguang Guo,Yajuan Sun,Zhongfan Liu,Yuanchang Li,Qian Wang,Yanfeng Zhang, Quasi-freestanding, striped WS2 monolayer with an invariable band gap on Au(001). NanoRes.2017, 10(11): 3875–3884