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Opportunity at National Institute of Standards and Technology (NIST)

Quantum Hall Effect in Epitaxial Graphene Monolayers

Location

Physical Measurement Laboratory, Quantum Measurement Division

RO# Location
50.68.41.B8166 Gaithersburg, MD

Please note: This Agency only participates in the February and August reviews.

Advisers

Name E-mail Phone
Elmquist, Randolph Ellis elmquist@nist.gov 301.975.6591
Newell, David B. david.newell@nist.gov 301.975.4228

Description

We focus on the unique physics of monolayer epitaxial graphene (EG) on the Si-face of SiC. SiC substrates are annealed at temperatures up to 2000 oC and fabricated in the NIST NanoFab using precious metal coatings to eliminate polymer residue. These growth and fabrication processes result in nearly pristine monolayer graphene of uniform high mobility and low carrier concentration, with p-type molecular doping that counteracts the high electron density in the as-grown state. We are seeking to understand the characteristics that influence device quality and performance, including EG interactions with the substrate, buffer layer, and contaminants or addition layers, localized electronic states, and e-e interactions.

We have overcome major challenges including suppression of EG’s non-uniform layer growth tendencies, where we restrict the growth to centimeter-size single-domain monolayer graphene; the substrate interactions and surface contamination, where we can control the carrier density near the Dirac point without external gates, and reach mobilities up to 6000 cm^2/Vs at n=4E11; and fabrication of robust, large-scale devices, where our centimeter-scale devices surpasses today’s best GaAs heterostructures in current capability and temperature operability for precise quantized Hall resistance (QHR) standards at T > 3 K and I > 500 mA.

The Associate could pursue independent study on fundamental quantum effects, interacting with other scientists working on graphene as well as quantum computing and single-electron devices. Resources include a vacuum/argon furnace for epitaxy, four variable-temperature high-field systems including a new milliKelvin high-field cryogen-free system, and extensive nanofabrication and imaging facilities at NIST.

 

Keywords:
Graphene; 2D systems; Conducting films; Electrical measurements; Quantum Hall effect; Nanotechnology; Functionalization; Resistance standards;

Eligibility

Citizenship:  Open to U.S. citizens
Level:  Open to Postdoctoral applicants
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