Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2.

By Yi Zhang, Tay-Rong Chang, Bo Zhou, Yong-Tao Cui, Hao Yan, Zhongkai Liu, F. Schmitt, James Lee, R. Moore, Yulin Chen and 6 more. Nature Nanotechnology, 2014

1,254 citations recorded by the source corpus.

Quantum systems in confined geometries are host to novel physical phenomena. Examples include quantum Hall systems in semiconductors and Dirac electrons in graphene. Interest in such systems has also been intensified by the recent discovery of a large enhancement in photoluminescence quantum efficiency and a potential route to valleytronics in atomically thin layers of transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te), which are closely related to the indirect-to-direct bandgap transition in monolayers. Here, we report the first direct observation of the transition from indirect to direct bandgap in monolayer samples by using angle-resolved photoemission spectroscopy on high-quality thin films of MoSe2 with variable thickness, grown by molecular beam epitaxy. The band structure measured experimentally indicates a stronger tendency of monolayer MoSe2 towards a direct bandgap, as well as a larger gap size, than theoretically predicted. Moreover, our finding of a significant spin-splitting of ∼ 180 meV at the valence band maximum of a monolayer MoSe2 film could expand its possible application to spintronic devices.

Subfields: Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/fc7ddc7c015c2e685e95428fb187f7c75a160668

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In Materials Chemistry

1. Hongyi Yu
2. W. Yao
3. Xiaodong Xu
4. X. Cui
5. Long-qing Chen
6. Feng Wang
7. Kai Xiao
8. Wenhui Duan

Citations in the corpus

• Optical properties of atomically thin transition metal dichalcogenides: observations and puzzles (2016, background): “[25] Zhang Y, Chang T-R, Zhou B, Cui Y-T, Yan H, Liu Z, Schmitt F, Lee J, Moore R, Chen Y, Lin H, Jeng H-T, et al.”
• Angle-resolved photoemission studies of quantum materials (2020, neutral): “41(f) (Cao et al., 2013; Zhang et al., 2013b).”
• Charge density wave order in 1D mirror twin boundaries of single-layer MoSe2 (2016, background): “org/uc/item/6mt7h7sn Journal Nature Physics, 12(8) ISSN 1745-2473 Authors Barja, S Wickenburg, S Liu, ZF et al.”