Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 16: Poster Ia

HL 16.3: Poster

Freitag, 4. März 2005, 16:30–19:00, Poster TU E

GaAs-based multi-terminal devices in lateral spin-valve geometry — •T. Last¹, M. Wahle¹, S.F. Fischer¹, U. Kunze¹, D. Reuter², and A.D. Wieck² — ¹Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — ²Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum

Essential for the detection of spin accumulation in a lateral ferromagnet(FM)-semiconductor(SC) spin-valve structure is the resistance-matching between the FM/SC contact resistance and the resistance of the semiconductor channel. We present a multi-terminal lateral FM/SC tunnelling device based on a GaAs-heterostructure. A 50 nm moderately n-doped (1x10¹⁶/cm³) GaAs layer is grown on semi-insulating undoped GaAs. On top of the n-doped GaAs layer a 10.5 nm thick δ-doped (1x10¹⁸/cm³) layer is introduced to reduce the width of the Schottky-barrier and to provide tunnelling as the major spin injection mechanism at low voltages. Permalloy electrodes are optimized in terms of uniform magnetization at the FM/SC contact and suitable switching behaviour: widths 2.0 µm and 0.4 µm (length: 150 µm, thickness: 30 nm) separated by 0.2 µm. Up to now no spin blockade is observed. Further experiments are in progress towards optimization of the matching of the contact and channel resistances.