Two-dimensional (2D) transition metal dichalcogenides (TMDs) have revealed many novel properties of interest to future device applications. In particular, the presence of grain boundaries (GBs) can significantly influence the material properties of 2D TMDs. However, direct characterization of the electronic properties of the GB defects at the atomic scale remains extremely challenging. In this study, we employ scanning tunneling microscopy and spectroscopy to investigate the atomic and electronic structure of low-angle GBs of monolayer tungsten diselenide (WSe2) with misorientation angles of 3-6°. Butterfly features are observed along the GBs, with the periodicity depending on the misorientation angle. Density functional theory calculations show that these butterfly features correspond to gap states that arise in tetragonal dislocation cores and extend to distorted six-membered rings around the dislocation core. Understanding the nature of GB defects and their influence on transport and other device properties highlights the importance of defect engineering in future 2D device fabrication. © 2016 American Chemical Society.
|Original language||English (US)|
|Number of pages||7|
|State||Published - May 9 2016|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: A.T.S.W. acknowledges financial support from MOE AcRF Tier 1 Grant No. R-144-000-321-112, and S.Y.Q, acknowledges support from Grant No. NRF-NRFF2013-07 from the National Research Foundation, Singapore. Computations were performed on the NUS Graphene Research Centre cluster. S.Y.Q. and A.T.S.W. acknowledge support from the Singapore National Research Foundation, Prime Minister's Office, under its medium-sized centre program. Y.L.H and D.C. acknowledge financial support from IMRE Pharos Project No. IMRE/15-2C0115.