1. Superconductivity in AuNiGe Ohmic contacts to a GaAs-based high mobility two-dimensional electron gas.
- Author
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Beauchamp, C. B., Dimitriadis, S., Nicholls, J. T., Levitin, L. V., Casey, A. J., See, P., Creeth, G., Waldie, J., Farrer, I., Beere, H. E., and Ritchie, D. A.
- Subjects
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TWO-dimensional electron gas , *ELECTRON gas , *ELECTRON mobility , *OHMIC contacts , *SUPERCONDUCTIVITY , *SCANNING electron microscopes , *OHMIC resistance - Abstract
To cool a high mobility two-dimensional electron gas (2DEG) at a GaAs–AlGaAs heterojunction to milliKelvin temperatures, we have fabricated low resistance Ohmic contacts based on alloys of Au, Ni, and Ge. The Ohmic contacts have a typical contact resistance of R C ≈ 0.8 Ω at 4.2 K, which drops to 0.2 Ω below 0.9 K. Scanning electron microscope images establish that the contacts have the same inhomogeneous microstructure that has been observed in previous studies. Measurements of the contact resistance R C , the four-terminal resistance along the top of a single contact, and the vertical resistance RV all show that there is a superconductor in the Ohmic contact, which can be turned completely normal with a magnetic field of 0.15 T. We briefly discuss how this superconductivity may be affecting the electrical transport measurements of 2DEGs, especially how it may hinder the cooling of electrons in a 2DEG below 0.1 K. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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