A van der Waals Heterostructure with an Electronically Textured Moiré Pattern
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2023-03-28
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en
Pages
8
5913-5920
5913-5920
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ACS Nano, Volume 17, issue 6
Abstract
The interlayer interaction in Pt-dichalcogenides strongly affects their electronic structures. The modulations of the interlayer atom-coordination in vertical heterostructures based on these materials are expected to laterally modify these interlayer interactions and thus provide an opportunity to texture the electronic structure. To determine the effects of local variation of the interlayer atom coordination on the electronic structure of PtSe2, van der Waals heterostructures of PtSe2 and PtTe2 have been synthesized by molecular beam epitaxy. The heterostructure forms a coincidence lattice with 13 unit cells of PtSe2 matching 12 unit cells of PtTe2, forming a moiré superstructure. The interaction with PtTe2 reduces the band gap of PtSe2 monolayers from 1.8 eV to 0.5 eV. While the band gap is uniform across the moiré unit cell, scanning tunneling spectroscopy and dI/dV mapping identify gap states that are localized within certain regions of the moiré unit cell. Deep states associated with chalcogen pz-orbitals at binding energies of ∼ -2 eV also exhibit lateral variation within the moiré unit cell, indicative of varying interlayer chalcogen interactions. Density functional theory calculations indicate that local variations in atom coordination in the moiré unit cell cause variations in the charge transfer from PtTe2 to PtSe2, thus affecting the value of the interface dipole. Experimentally this is confirmed by measuring the local work function by field emission resonance spectroscopy, which reveals a large work function modulation of ∼0.5 eV within the moiré structure.Description
Funding Information: Financial support from the National Science Foundation under award 2140038 is acknowledged. A.V.K. thanks the German Research Foundation (DFG) for support through Project KR 4866/6-1 and the collaborative research center “Chemistry of Synthetic 2D Materials” SFB-1415-417590517. The authors further thank the HZDR Computing Center, HLRS, Stuttgart, Germany, and TU Dresden Cluster “Taurus” for generous grants of CPU time. Publisher Copyright: © 2023 American Chemical Society
Keywords
moiré pattern, PtSe, scanning tunneling microscopy, transition metal dichalcogenide, van der Waals heterostructure, work function
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Li , J , Ghorbani-Asl , M , Lasek , K , Pathirage , V , Krasheninnikov , A V & Batzill , M 2023 , ' A van der Waals Heterostructure with an Electronically Textured Moiré Pattern : PtSe 2 /PtTe 2 ' , ACS Nano , vol. 17 , no. 6 , pp. 5913-5920 . https://doi.org/10.1021/acsnano.2c12879