nn8b09054_si_001.pdf (574.74 kB)
Interface Engineering of Au(111) for the Growth of 1T′-MoSe2
journal contribution
posted on 2019-01-11, 00:00 authored by Fang Cheng, Zhixin Hu, Hai Xu, Yan Shao, Jie Su, Zhi Chen, Wei Ji, Kian Ping LohPhase-controlled
synthesis of two-dimensional transition-metal
dichalcogenides (TMDCs) is of great interest due to the distinct properties
of the different phases. However, it is challenging to prepare metallic
phase of group-VI TMDCs due to their metastability. At the monolayer
level, interface engineering can be used to stabilize the metastable
phase. Here, we demonstrate the selective growth of either single-layer
1H- or 1T′-MoSe2 on Au(111) by molecular-beam epitaxy;
the two phases can be unambiguously distinguished using scanning tunnelling
microscopy and spectroscopy. While the growth of 1H-MoSe2 is favorable on pristine Au(111), the growth of 1T′-MoSe2 is promoted by the predeposition of Se on Au(111). The selective
growth of the 1T′-MoSe2 on Se-pretreated Au(111)
is attributed to the Mo intercalation induced stabilization of the
1T′ phase, which is supported by density functional theory
calculations. In addition, 1T′ twin boundaries and 1H–1T′
heterojunctions were observed and found to exhibit enhanced tunnelling
conductivity. The substrate pretreatment approach for phase-controlled
epitaxy could be applicable to other group-VI TMDCs grown on Au (111).