Electron transport in bilayer graphene nano constrictions patterned using AFM nanolithography

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Bilayer graphene exhibits unique electronic properties.
• Fabricating nanoscale constrictions in graphene is crucial for quantum devices.
• Existing lithography techniques face limitations in achieving ultra-narrow structures.

Purpose of the Study:

• To report on low-temperature transport measurements of encapsulated bilayer graphene nanoconstrictions.
• To introduce and evaluate electrode-free AFM-based local anodic oxidation (LAO) nanolithography for fabricating nanostructures.
• To investigate the electronic properties of graphene nanoconstrictions with widths down to 20 nm.

Main Methods:

• Fabrication of encapsulated bilayer graphene nanoconstrictions using electrode-free AFM-based LAO nanolithography.
• Low-temperature electrical transport measurements.
• Analysis of transport characteristics as a function of constriction width.

Main Results:

• Successful fabrication of graphene nanoconstrictions as narrow as 20 nm.
• Observation of bulk transport in wider constrictions and a transport gap in narrower ones.
• Formation of single quantum dots (QDs) in the narrowest constrictions with addition energies > 100 meV.
• Transport governed by edge disorder and quantum confinement effects.

Conclusions:

• Electrode-free AFM-LAO lithography is a flexible method for creating ultra-narrow graphene nanostructures.
• The technique allows for tunable electronic properties without complex patterning.
• This method surpasses previous QD fabrication techniques and offers potential for novel electronic devices.