Journal
NANO LETTERS
Volume 21, Issue 17, Pages 7100-7108Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.1c01442
Keywords
Bilayer graphene; graphite; scanning tunneling microscopy; quasiparticle interference; dopant
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Funding
- National Science Foundation [DMR-1753367]
- Army Research Office [W911NF-17-1-0473]
- Elemental Strategy Initiative [JPMXP0112101001]
- JSPS KAKENHI [JP20H00354]
- Royal Society through a Royal Society University Research Fellowship
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Graphite commonly used for preparing graphene devices contains a significant amount of native defects, impacting the electronic properties of Bernal-stacked bilayer graphene. The distribution of scattering vectors shows a clear carrier density dependence. The dilute native defects identified in the study are found to be an important extrinsic source of scattering, influencing charge carrier mobility at low temperatures.
Graphite crystals used to prepare graphene-based heterostructures are generally assumed to be defect free. We report here scanning tunneling microscopy results that show graphite commonly used to prepare graphene devices can contain a significant amount of native defects. Extensive scanning of the surface allows us to determine the concentration of native defects to be 6.6 x 10(8) cm(-2). We further study the effects of these native defects on the electronic properties of Bernal-stacked bilayer graphene. We observe gate-dependent intravalley scattering and successfully compare our experimental results to T-matrix-based calculations, revealing a clear carrier density dependence in the distribution of the scattering vectors. We also present a technique for evaluating the spatial distribution of short-scale scattering. Finally, we present a theoretical analysis based on the Boltzmann transport equation that predicts that the dilute native defects identified in our study are an important extrinsic source of scattering, ultimately setting the charge carrier mobility at low temperatures.
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