Morphology control of epitaxial monolayer transition metal dichalcogenides
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To advance fundamental understanding and ultimate application of transition-metal dichalcogenide (TMD) monolayers, it is essential to develop capabilities for the synthesis of high-quality single-layer samples. Molecular beam epitaxy (MBE), a leading technique for the fabrication of the highest-quality epitaxial films of conventional semiconductors has, however, typically yielded only small grain sizes and suboptimal morphologies when applied to the van der Waals growth of monolayer TMDs. Here, we present a systematic study on the influence of adatom mobility, growth rate, and metal:chalcogen flux on the growth of NbSe2, VSe2, and TiSe2 using MBE. Through this, we identify the key drivers and influence of the adatom kinetics that control the epitaxial growth of TMDs, realizing four distinct morphologies of the as-grown compounds. We use this to determine optimized growth conditions for the fabrication of high-quality monolayers, ultimately realizing the largest grain sizes of monolayer TMDs that have been achieved to date via MBE growth.
Rajan , A , Underwood , K , Mazzola , F & King , P 2020 , ' Morphology control of epitaxial monolayer transition metal dichalcogenides ' , Physical Review Materials , vol. 4 , no. 1 , 014003 . https://doi.org/10.1103/PhysRevMaterials.4.014003
Physical Review Materials
Copyright © 2019 American Physical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1103/PhysRevMaterials.4.014003
DescriptionFunding: AFM system (funded via an EPSRC equipment grant: EP/L017008/1) used in this work and experimental support. The Leverhulme Trust (Grant no. RL-2016-006); The Royal Society; the European Research Council (Grant No. ERC-714193-QUESTDO). K.U. acknowledges EPSRC for PhD studentship support through grant no. EP/L015110/1.
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