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Charge Puddles in Graphene near the Dirac Point
S Samaddar1,2, I Yudhistira3, S Adam3,4
1Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France.
Physical Review Letters
|April 9, 2016
Summary
Charge puddles in graphene grow larger and more intense near charge neutrality, unlike conventional electron gases. This study directly observes this phenomenon, confirming theoretical predictions about graphene
Area of Science:
- Condensed matter physics
- Materials science
- Surface science
Background:
- Graphene exhibits unique electronic properties due to its linear dispersion relation.
- Charge carrier density in graphene on dielectric substrates shows inhomogeneities known as charge puddles.
- Conventional two-dimensional electron gases behave differently regarding charge puddle formation.
Purpose of the Study:
- To directly observe and characterize the growth of charge puddles in graphene.
- To investigate the influence of the Fermi level approaching the Dirac point on charge puddles.
- To unify the description of macroscopic transport and microscopic charge disorder in graphene.
Main Methods:
- Scanning tunneling microscopy (STM) for spatial imaging.
- Scanning tunneling spectroscopy (STS) for electronic properties.
- Fabrication of mesoscopic graphene devices for controlled experiments.
Main Results:
- Direct observation of charge puddle growth in spatial extent and amplitude.
- Confirmation that puddles grow as the Fermi level approaches the Dirac point.
- Experimental data aligns with theoretical predictions for graphene.
Conclusions:
- Charge puddles in graphene exhibit distinct growth behavior near charge neutrality.
- Self-consistent screening theory successfully explains both macroscopic and microscopic observations.
- The findings provide a unified understanding of charge disorder in graphene devices.
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