Transport Measurements of Surface Electrons in 200-nm-Deep Helium-Filled Microchannels Above Amorphous Metallic Electrodes

Journal Article · 07 January 2019 · Journal of Low Temperature Physics

DOI: https://doi.org/10.1007/s10909-018-02139-6 · OSTI ID:1492721

Asfaw, A. T.  ^[1]; Kleinbaum, E. I. ^[1]; Henry, M. D. ^[2]; Shaner, E. A. ^[2]; Lyon, S. A. ^[1]

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1. Princeton Univ., NJ (United States). Dept. of Electrical Engineering
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

We report transport measurements of electrons on helium in a microchannel device where the channels are 200 nm deep and 3μm wide. The channels are fabricated above amorphous metallic Ta₄₀W₄₀Si₂₀, which has surface roughness below 1 nm and minimal variations in work function across the surface due to the absence of polycrystalline grains. We are able to set the electron density in the channels using a ground plane. We estimate a mobility of 300cm²/Vs and electron densities as high as 2.56×10⁹ cm^-2. We demonstrate control of the transport using a barrier which enables pinch-off at a central microchannel connecting two reservoirs. The conductance through the central microchannel is measured to be 10 nS for an electron density of 1.58×10⁹ cm^-2. Lastly, our work extends transport measurements of surface electrons to thin helium films in microchannel devices above metallic substrates.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1492721
• Report Number(s): SAND--2019-0605J; 671686
• Journal Information: Journal of Low Temperature Physics, Journal Name: Journal of Low Temperature Physics; ISSN 0022-2291
• Publisher: Plenum PressCopyright Statement
• Country of Publication: United States
• Language: English