Towards epitaxial graphene p-n junctions as electrically programmable quantum resistance standards

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Metrology

Background:

• Epitaxial graphene offers unique electronic properties for device applications.
• Hexagonal boron nitride (h-BN) is a promising dielectric material due to its insulating properties and atomic flatness.
• Accurate resistance standards are crucial for metrology and fundamental physics research.

Purpose of the Study:

• To fabricate and characterize top-gated epitaxial graphene p-n junctions using h-BN as a dielectric.
• To investigate the quantized resistance properties of these junctions.
• To explore the potential of these devices as programmable electrical resistance standards.

Main Methods:

• Fabrication of top-gated epitaxial graphene p-n junctions.
• Utilizing exfoliated hexagonal boron nitride (h-BN) as the gate dielectric.
• Measurement of four-terminal longitudinal resistance at low temperatures.

Main Results:

• The four-terminal longitudinal resistance was found to be well quantized at the von Klitzing constant (R_K).
• A relative uncertainty of 10^-7 was achieved for the quantized resistance.
• Conditions for device functionality as resistance standards were identified.

Conclusions:

• Epitaxial graphene p-n junctions with h-BN dielectric exhibit quantized resistance suitable for metrology.
• These devices can be engineered as programmable electrical resistance standards over a wide dynamic range.
• The findings contribute to the development of next-generation resistance standards.