Quantum Wires and Waveguides Formed in Graphene by Strain

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Electron confinement in graphene for devices is difficult due to Klein tunneling and fabrication limitations.
• Mechanical flexibility of graphene offers potential for strain-induced property changes and straintronic devices.

Purpose of the Study:

• Investigate the use of strain-induced folds in graphene as quantum wires.
• Explore the transport properties and confinement effects in these folded graphene structures.

Main Methods:

• Fabrication of graphene nanowires via layer transfer onto hexagonal boron nitride, creating linear strained regions (folds).
• Transport studies including conductance measurements across folds and traverse resistivity measurements along folds.
• Theoretical calculations using the Dirac model with strain.

Main Results:

• Coulomb blockade signatures observed across folds, indicating quantum dot formation and charge confinement.
• Sharp features in resistivity measurements attributed to resistance bridge amplification of conductance modulations.
• Ballistic transport observed up to ~1 μm along the folds.
• Calculations consistent with bound state energies and predict valley-polarized currents.

Conclusions:

• Graphene folds act as effective straintronic quantum wires.
• Strain engineering in graphene provides a viable method for creating novel electronic devices.
• Demonstrated potential for controlled electron confinement and transport in folded graphene structures.