Berlin 2005 – scientific programme
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HL: Halbleiterphysik
HL 58: Poster IIb
HL 58.67: Poster
Tuesday, March 8, 2005, 16:30–19:00, Poster TU F
Low-ohmic contacts to two-dimensional electron gases in GaAs/AlGaAs heterostructures — •S. Raiser1, U. Graumann2, M. Fleischer1, J. Schmid2, S. Jauerneck1, J. Weis2, and D.A. Wharam1 — 1Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart
The reliable contacting of two-dimensional electron gases is an essential prerequisite for the low-temperature characterisation of heterostructure-devices. In the past it has often been difficult to produce high quality ohmic contacts. For the low-resistance ohmic contacts presented here we use standard AuGe/Ni/Au-metallisation with significantly different parameters than conventional recipes. We are now able to produce low-ohmic contacts with perfect reliability. The quality of the contacts has been investigated with respect to processing parameters such as the thickness of the metallisation layers, alloying temperature, and alloying time. The dependence of the contact geometry has been examined, whereby a dependence upon the orientation with respect to the crystallographic direction has been found. Initial studies of the contact structure have been performed using electron microscopy.