Ultrasharp Lateral p-n Junctions in Modulation-Doped Graphene

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Graphene's unique electronic properties make it a candidate for advanced electronic devices.
• Achieving precisely controlled doping and sharp lateral p-n junctions in graphene remains a significant challenge.
• The development of nanoscale electronic components requires precise control over material interfaces.

Purpose of the Study:

• To demonstrate and characterize ultrasharp lateral p-n junctions in graphene.
• To investigate the influence of alpha-ruthenium trichloride (α-RuCl3) on graphene doping.
• To determine the minimum achievable width of graphene p-n junctions.

Main Methods:

• Utilizing electronic transport measurements to probe device resistance.
• Employing scanning tunneling microscopy (STM) for nanoscale imaging.
• Performing first-principles calculations to understand doping mechanisms.
• Conducting scanning tunneling spectroscopy (STS) on graphene/hexagonal boron nitride/α-RuCl3 heterostructures.

Main Results:

• Demonstrated lateral p-n junctions in graphene with widths below 10 nm.
• Achieved ultrasharp junctions by using a cleaved crystalline edge of α-RuCl3 positioned 2 nm from graphene.
• Observed rapid decay of charge doping in graphene from the α-RuCl3 edge on a nanometer scale.
• STS revealed potential variations on sub-10 nm length scales in heterostructures.

Conclusions:

• Ultrasharp lateral p-n junctions in graphene are achievable using proximity doping with α-RuCl3.
• The junction width is strongly dependent on the interface quality and proximity to the α-RuCl3 edge.
• These findings pave the way for nanoscale electronic devices with precisely engineered graphene interfaces.