Sub-5 nm Contacts and Induced p-n Junction Formation in Individual Atomically Precise Graphene Nanoribbons

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Graphene nanoribbons (GNRs) are promising semiconductor materials.
• Controlling GNR electronic properties is crucial for device applications.
• Existing methods for GNR modification can be complex and challenging.

Purpose of the Study:

• To demonstrate the fabrication of nanoscale metal contacts on individual GNRs.
• To show how these contacts can control the electronic character of GNRs.
• To achieve local p-n junction formation on GNRs.

Main Methods:

• Utilized a low-voltage direct-write scanning tunneling microscope (STM)-based process.
• Fabricated sub-5 nm hafnium diboride (HfB2) metallic contacts on single GNRs.
• Performed fabrication in an ultrahigh-vacuum (UHV-STM) environment on a silicon substrate.

Main Results:

• Successfully patterned precise metallic contacts on individual GNRs.
• Scanning tunneling spectroscopy (STS) confirmed metallic contacts and semiconducting GNRs.
• Observed induced band bending and p-n junction formation due to work function differences.

Conclusions:

• Contact engineering with different work function metals offers an alternative to chemical doping for GNRs.
• This work demonstrates a viable method for creating precise metal contacts and local p-n junctions on single GNRs.
• The developed technique provides a pathway for advanced GNR-based electronic devices.