Yin, X., Wang, Q., Cao, L., Tang, C. S., Luo, X., Zheng, Y., … Wee, A. T. S. (2017). Tunable inverted gap in monolayer quasi-metallic MoS2 induced by strong charge-lattice coupling. Nature Communications, 8(1). doi:10.1038/s41467-017-00640-2
Abstract:
Polymorphism of two-dimensional transition metal dichalcogenides such as molybdenum disulfide (MoS2) exhibit fascinating optical and transport properties. Here, we observe a tunable inverted gap (~0.50 eV) and a fundamental gap (~0.10 eV) in quasimetallic monolayer MoS2. Using spectral-weight transfer analysis, we find that the inverted gap is attributed to the strong charge–lattice coupling in two-dimensional transition metal dichalcogenides (2D-TMDs). A comprehensive experimental study, supported by theoretical calculations, is conducted to understand the transition of monolayer MoS2 on gold film from trigonal semiconducting 1H phase to the distorted octahedral quasimetallic 1T’ phase. We clarify that electron doping from gold, facilitated by interfacial tensile strain, is the key mechanism leading to its 1H–1T’ phase transition, thus resulting in the formation of the inverted gap. Our result shows the importance of charge–lattice coupling to the intrinsic properties of the inverted gap and polymorphism of MoS2, thereby unlocking new possibilities for 2D-TMD-based device fabrication.
License type:
Attribution 4.0 International (CC BY 4.0)
Funding Info:
This research / project is supported by the National Natural Science Foundation of China - National Natural Science Foundation of China
Grant Reference no. : (51472164)
This research / project is supported by the Natural Science Foundation of SZU - Natural Science Foundation of SZU
Grant Reference no. : 000050
This research / project is supported by the the 1000 Talents Program for Young Scientists of China, Shenzhen Peacock Plan - the 1000 Talents Program for Young Scientists of China, Shenzhen Peacock Plan
Grant Reference no. : KQTD2016053112042971
This research / project is supported by the the Educational Commission of Guangdong Province - the Educational Commission of Guangdong Province
Grant Reference no. : 2015KGJHZ006
This research / project is supported by the the Science and Technology Planning Project of Guangdong Province - the Science and Technology Planning Project of Guangdong Province
Grant Reference no. : 2016B050501005
This research / project is supported by the the China Postdoctoral Science Foundation funded project - the China Postdoctoral Science Foundation funded project
Grant Reference no. : 2016M600664
This research / project is supported by the Singapore National Research Foundation - Competitive Research Funding
Grant Reference no. : NRF-CRP 8-2011-06 and NRF-CRP15-2015-01
This research / project is supported by the Ministry of Education (Singapore) - MOE-AcRF Tier-2
Grant Reference no. : (MOE2015-T2-1-099, MOE2015-T2-1-099 and MOE2015-T2-2-147)
This research / project is supported by the Hubert Curien Partnerships (PHC) - 2015 PHC Merlion Project and FRC
Grant Reference no. : (R-144-000-368-112, R-144-000-346-112 and R-144-000-364-112)