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

✍ Scribed by K.-M.H. Lenssen; L.A. Westerling; P.C.A. Jeekel; C.J.P.M. Harmans; J.E. Mooij; M.R. Leys; W. van der Vleuten; J.H. Wolter; S.P. Beaumont

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 158 KB
• Volume: 194-196
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(94)91706-x

✦ Synopsis

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/AIGaAsheterostructure 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.