期刊
APPLIED SURFACE SCIENCE
卷 541, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apsusc.2020.148612
关键词
Graphene; Extremely high displacement field; Electronic structure; ARPES; Air exposure
类别
资金
- Australian Research Council [DP150103837, DP200101345, FL120100038, CE17010039]
- Australian Government Research Training Program
- Monash Centre for Atomically Thin Materials
- Monash University Summer Vacation Research Scholarship Program
- Monash University Summer ResearchFirst Scholarships Program
- core programs at the U.S. Naval Research Laboratory - Office of Naval Research
- Australian Research Council [DP200101345, FL120100038] Funding Source: Australian Research Council
The electronic structure of bilayer graphene was investigated using angle-resolved photoemission spectroscopy under high n-doping and extreme displacement fields. Intercalation of magnesium transformed the single massless Dirac band of monolayer graphene into the characteristic massive double-band Dirac spectrum of quasi-freestanding bilayer graphene. This resulted in an n-type doping of 2.1 x 10(14) cm(-2) and an extremely high displacement field of 2.6 V/nm, creating a significant gap of 0.36 eV at the Dirac point.
We use angle-resolved photoemission spectroscopy to investigate the electronic structure of bilayer graphene at high n-doping and extreme displacement fields, created by intercalating epitaxial monolayer graphene on silicon carbide with magnesium to form quasi-freestanding bilayer graphene on magnesium-terminated silicon carbide. Angle-resolved photoemission spectroscopy reveals that upon magnesium intercalation, the single massless Dirac band of epitaxial monolayer graphene is transformed into the characteristic massive double-band Dirac spectrum of quasi-freestanding bilayer graphene. Analysis of the spectrum using a simple tight binding model indicates that magnesium intercalation results in an n-type doping of 2.1 x 10(14) cm(-2) and creates an extremely high displacement field of 2.6 V/nm, thus opening a considerable gap of 0.36 eV at the Dirac point. This is further confirmed by density-functional theory calculations for quasi-freestanding bilayer graphene on magnesium-terminated silicon carbide, which show a similar doping level, displacement field and bandgap. Finally, magnesium-intercalated samples are surprisingly robust to ambient conditions; no significant changes in the electronic structure are observed after 30 min exposure to air.
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