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Lecture Sylvain Le Gall


14 January 2011 FWN-Building 5118.-152, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Sylvain Le Gall
Affiliation: Institut de Physique de Rennes
Equipe Physique des Surfaces et Interfaces
Bât 11 C, Campus de Beaulieu, 35042 Rennes cedex, France
Title: Transport properties study of MgO/GaAs(001) contacts for spintronics
Date: Fri Jan 14, 2011
Start: 10.00
Location: FWN-Building 5118.-152
Host: B.J. van Wees
Telephone: +31 50 363 4974


The background of this work is the growing development of spintronic devices based on injection and detection of spin polarized current from a ferromagnetic metal (FM) into a semiconductor (SC) through a thin oxide tunnel barrier. The FM/MgO/GaAs contact appears as very promising candidate [1]. In this framework, we have studied the transport mechanisms and electrical properties methods of Au/MgO/GaAs heterojunctions using I(V) and C(V) for various doping concentration and oxide thickness. We have determined the transport mechanisms which control the current injection and understood the mode of operation of this kind of structures. Our results show that the Fert and Jaffrès’s theoretical criterion for lateral FM/tunnel barrier/SC/tunnel barrier/FM structure [2] is not fulfilled for none metal /MgO/GaAs junctions: this study demonstrate that it is not possible to inject and detect spin-polarized current efficiently through MgO/GaAs contact at room temperature with our growth method. The main fundamental reason for this failure is that deposition of MgO induces defects which extend on a depth of several tens of nanometer in semiconductor band gap.

Last modified:22 October 2012 2.31 p.m.