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Nat Nanotechnol. 2018 Jul;13(7):566-571. doi: 10.1038/s41565-018-0138-7. Epub 2018 May 7.

Band structure engineering of 2D materials using patterned dielectric superlattices.

Author information

1
Department of Physics, Columbia University, New York, NY, USA.
2
Laboratory of Advanced Materials, Fudan University, Shanghai, China.
3
National Institute for Materials Science, Tsukuba, Japan.
4
NYU Shanghai, Shanghai, China.
5
NYU-ECNU Institute of Physics at NYU Shanghai, Shanghai, China.
6
Department of Physics, Osaka University, Toyonaka, Japan.
7
Department of Physics, Harvard University, Cambridge, MA, USA.
8
Department of Physics, Columbia University, New York, NY, USA. cd2478@columbia.edu.

Abstract

The ability to manipulate electrons in two-dimensional materials with external electric fields provides a route to synthetic band engineering. By imposing artificially designed and spatially periodic superlattice potentials, electronic properties can be further altered beyond the constraints of naturally occurring atomic crystals1-5. Here, we report a new approach to fabricate high-mobility superlattice devices by integrating surface dielectric patterning with atomically thin van der Waals materials. By separating the device assembly and superlattice fabrication processes, we address the intractable trade-off between device processing and mobility degradation that constrains superlattice engineering in conventional systems. The improved electrostatics of atomically thin materials allows smaller wavelength superlattice patterns relative to previous demonstrations. Moreover, we observe the formation of replica Dirac cones in ballistic graphene devices with sub-40 nm wavelength superlattices and report fractal Hofstadter spectra6-8 under large magnetic fields from superlattices with designed lattice symmetries that differ from that of the host crystal. Our results establish a robust and versatile technique for band structure engineering of graphene and related van der Waals materials with dynamic tunability.

PMID:
29736033
DOI:
10.1038/s41565-018-0138-7

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