Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 5: Transporteigenschaften

HL 5.4: Talk

Monday, March 8, 2004, 11:00–11:15, H14

Nonplanar two-dimensional electron gases in InAs heterostructures on GaAs — •S. Löhr, Ch. Heyn, and W. Hansen — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstraße 11, D-20355 Hamburg, Germany

We present transport properties of a two-dimensional electron gas (2DEG) in an InAs/InGaAs quantum well grown by molecular beam epitaxy on a GaAs substrate. The experiments are performed in magnetic fields tilted with respect to the sample normal. Depending on the relative orientation of the current flow and the tilt direction, i.e., the direction of the magnetic field component parallel to the sample substrate, we observe a pronounced positive magnetoresistance and a strong damping of the Shubnikov-de Haas oscillations. Both effects increase with the tilt angle. We show that these findings are direct evidence of a nonplanar 2DEG, resulting from the lattice-mismatched epitaxial growth of this InAs-based structure on GaAs, which also causes a cross-hatch topography at the sample surface. An estimation of the 2DEG curvature suggests that the strength of the curvature-induced spin-orbit interaction (M.V. Entin et al., PRB 64, 85330 (2001)) may be comparable to the Rashba spin-orbit coupling found in this kind of heterostructure.