Strain-induced pseudo-magnetic fields and charging effects on CVD-grown graphene

SURFACE SCIENCE

卷:605

Article

Yeh, N. -C.¹  Teague, M. -L.¹  Yeom, S.²  Standley, B. L.²  Wu, R. T. -P.¹  Boyd, D. A.²  Bockrath, M. W.² 

[1] CALTECH, Dept Phys, Pasadena, CA 91125 USA

[2] CALTECH, Dept Appl Phys, Pasadena, CA 91125 USA

关键词: Scanning tunneling microscopy;    Scanning tunneling spectroscopies;    Chemical vapor deposition;    Quantum effects;    Surface structure;    Morphology;    Topography;    Carbon;   

DOI  :  10.1016/j.susc.2011.03.025

来源: Elsevier

【 摘 要 】

Atomically resolved imaging and spectroscopic characteristics of graphene grown by chemical vapor deposition (CVD) on copper are investigated by means of scanning tunneling microscopy and spectroscopy (STM/STS). For CVD-grown graphene remaining on the copper substrate, the monolayer carbon structures exhibit ripples and appear strongly strained, with different regions exhibiting different lattice structures and electronic density of states (DOS). In particular, ridges appear along the boundaries of different lattice structures, which exhibit excess charging effects. Additionally, the large and non-uniform strain induces pseudo-magnetic field up to similar to 50 T, as manifested by the DOS peaks at quantized energies that correspond to pseudo-magnetic field-induced integer and fractional Landau levels. In contrast, for graphene transferred from copper to SiO2 substrates after the CVD growth, the average strain on the whole diminishes, so do the corresponding charging effects and pseudo-magnetic fields except for sample areas near topological defects. These findings suggest feasible nano-scale strain engineering of the electronic states of graphene by proper design of the substrates and growth conditions. (C) 2011 Elsevier B.V. All rights reserved.

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