Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 53: Transport im hohen Magnetfeld/Quanten-Hall-Effekt

HL 53.7: Talk

Tuesday, March 8, 2005, 16:30–16:45, TU P270

First experiments in epitaxial growing of carbon doped two-dimensional hole gases (2DHGs) in GaAs/AlGaAs heterostructures resulting in mobilities beyond 10⁶cm²/Vs — •Christian Gerl, Stefan Schmult, Hans Peter Tranitz, and Werner Wegscheider — Universität Regensburg, Institut für Experimentelle und Angewandte Physik, 93040 Regensburg

The almost perfect lattice match between Galliumarsenide (GaAs) and Aluminumarsenide (AlAs) yield some important developments in the heteroepitaxy within the last 30 years. Results are for example high electron mobility two-dimensional electron gases exceeding mobility values in the order of 10⁷cm²/Vs. High electron mobilities are essential for the fractional quantum hall effect. Even if the epitaxial growth of low-dimensional high mobility electron systems in GaAs/AlGaAs heterostructures is a state of the art technique today, the growth of similar holes systems is still a fundamental challenge. Beryllium, for instance, acts like an acceptor in (001) GaAs and AlGaAs, with the disadvantage of the segregation for the underlying growth conditions. Silicon, acting as the standard donor in the considered material system for many growth directions, can also yield hole doping, e.g. on (311) GaAs. Recently, the signature of the quantum hall effect in carbon-doped 2DHGs has been reported. We will present our results on C-doped high mobility 2DHGs in the heterosystem GaAs/Al_0.33Ga_0.67As. Optimization has led to hole mobilities up to 1.1×10⁶cm²/Vs at densities of 2.5×10¹¹cm² determined in low temperature magnetotransport measurements.