Electron transport in mesoscopic GaAs/AlGaAs-structures with superconducting contacts

For the first time an enhancement of weak localization by Andreev-reflection has been measured. This means that the interface between the Sn/Ti contacts and the two-dimensional electron gas (2DEG) in the GaAs/AlGaAs-heterostructure is practically barrier-free. The effect can be depressed by increase...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 1994-01, Vol.194-96, p.2413-2414
Main Authors: Lenssen, K-M H, Westerling, L A, Jeekel, P C A, Harmans, CJPM, Mooij, J E, Leys, M R, van der Vleuten, W, Wolter, J H, Beaumont, S P
Format: Article
Language:English
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Summary:For the first time an enhancement of weak localization by Andreev-reflection has been measured. This means that the interface between the Sn/Ti contacts and the two-dimensional electron gas (2DEG) in the GaAs/AlGaAs-heterostructure is practically barrier-free. The effect can be depressed by increased temperature, a DC bias current or a small magnetic field, but also by a voltage on a nearby gate. Also the sign of the temperature dependence of the differential resistance changes when the weak localization has disappeared. Further we report preliminary measurements on superconducting contacts to a shallow 2DEG. The transmission of this interface is probably not very high, since there are indications for an excess conductance caused by reflectionless tunneling.
ISSN:0921-4526