Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 23: Spin controlled transport II

HL 23.5: Vortrag

Dienstag, 27. März 2007, 15:00–15:15, H14

Spin-Orbit Coupling in AlGaN/GaN 2-Dimensional Electron Gases — •Sergio Cabañas, Nicolas Thillosen, Nicoleta Kaluza, Patrick Lehnen, Vitaliy Guzenko, Hilde Hardtdegen, and Thomas Schäpers — Institute of Bio- and Nanosystemes (IBN-1) and CNI Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany

AlGaN/GaN is a very promising material system for spin electronic devices, because for GaN-based diluted magnetic semiconductors Curie temperatures above room temperature have been predicted theoretically and confirmed experimentally. We have investigated weak antilocalization in AlGaN/GaN heterostructures. By fitting the experimental curves to a theoretical model we found that the decrease of the peak height in the conductivity with temperature is solely due to the decrease of the phase coherence length. Measurements on gated samples showed that the spin-orbit scattering length is constant for all carrier concentrations. This behavior is due to the fact that the spin-orbit scattering due to crystal inversion asymmetry is the dominant contribution. Although GaN is a large band gap material, the spin-orbit scattering length has a relatively small value of approximately 300 nm, which makes this material interesting for spin electron devices relying on spin precession. If a magnetic field is applied parallel to the plane of the 2-dimensional electron gas the weak antilocalization can be suppressed. We attribute the vanishing of the weak antilocalization peak to the additional contribution of the Zeeman energy competing with the characteristic spin-orbit energy.