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Fast Twist Angle Mapping of Bilayer Graphene Using Spectroscopic Ellipsometric Contrast Microscopy.

Accepted version
Peer-reviewed

Type

Article

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Authors

Potočnik, Teja 
Schmitt, David 
Bange, Jan Philipp 

Abstract

Twisted bilayer graphene provides an ideal solid-state model to explore correlated material properties and opportunities for a variety of optoelectronic applications, but reliable, fast characterization of the twist angle remains a challenge. Here we introduce spectroscopic ellipsometric contrast microscopy (SECM) as a tool for mapping twist angle disorder in optically resonant twisted bilayer graphene. We optimize the ellipsometric angles to enhance the image contrast based on measured and calculated reflection coefficients of incident light. The optical resonances associated with van Hove singularities correlate well to Raman and angle-resolved photoelectron emission spectroscopy, confirming the accuracy of SECM. The results highlight the advantages of SECM, which proves to be a fast, nondestructive method for characterization of twisted bilayer graphene over large areas, unlocking process, material, and device screening and cross-correlative measurement potential for bilayer and multilayer materials.

Description

Keywords

ellipsometric contrast microscopy, spectroscopic imaging ellipsometry, twisted bilayer graphene

Journal Title

Nano Lett

Conference Name

Journal ISSN

1530-6984
1530-6992

Volume Title

Publisher

American Chemical Society (ACS)
Sponsorship
Royal Society (DHF\F1\191163)
Engineering and Physical Sciences Research Council (EP/P005152/1)
European Research Council (716471)
EPSRC (EP/T001038/1)
EPSRC (EP/V055003/1)
J.A.-W. acknowledges the support of his Royal Society Dorothy Hodgkin Research Fellowship and the EPSRC (EP/V055003/1). M.R., D.S., J.P.B, R.T.W. and S.M. acknowledges funding through the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 217133147/SFB 1073, projects B07 and B10. S.H. acknowledges funding from EPSRC (EP/P005152/1) and Cambridge-LMU Strategic Partnership. H.J.J. acknowledges the support of the ERC (Grant No. 716471, ACrossWire).
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