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Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
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Ballistic bipolar junctions in chemically gated graphene ribbons
Jens Baringhaus1, Alexander Stöhr2, Stiven Forti2
1Institut für Festkörperphysik, Leibniz Universität Hannover, Germany.
Scientific Reports
|April 22, 2015
Summary
Researchers created ultra-narrow graphene pn-junctions for studying Klein tunneling. These 5 nm junctions exhibit ballistic transmission, acting as polarizers and analyzers for electron transport.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Studying Klein tunneling phenomena requires ballistic graphene pn-junctions.
- Previous methods resulted in wider junctions (hundreds of nanometers) compared to ideal nano-scaled structures.
Purpose of the Study:
- To realize truly nano-scaled graphene pn-junctions for Klein tunneling research.
- To investigate ballistic transmission and polarization effects in these junctions.
Main Methods:
- Intercalation of Germanium (Ge) under a buffer layer of pre-structured Silicon Carbide (SiC) samples.
- Local tunneling spectroscopy to determine junction width.
- Four-tip scanning tunneling microscopy (STM) for systematic transport measurements.
Main Results:
- Successfully fabricated nano-scaled pn-junctions with a width as narrow as 5 nm.
- Directly demonstrated ballistic transmission across the junctions using transport measurements.
- Observed pn-junctions acting as polarizers/analyzers, with transparency in npn/pnp structures under specific conditions.
Conclusions:
- Ge intercalation provides a method for creating ultra-narrow graphene pn-junctions.
- These junctions facilitate the study of Klein tunneling due to ballistic transmission.
- The observed polarization effects are linked to suppressed electron transmission away from normal incidence.
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