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HL: Fachverband Halbleiterphysik

HL 48: Transport

HL 48.7: Vortrag

Dienstag, 1. April 2014, 15:30–15:45, POT 006

Magnetoresistance studies in GaAs/AlGaAs quantum wells with additional impurity — •Eddy P. Rugeramigabo^1,2, Lina Bockhorn¹, and Rolf J. Haug¹ — ¹Institute for Solid State Physics, Dep. Nanostructures, Leibniz Universität Hannover — ²QUEST Centre for Quantum Engineering and Space-Time Research, Leibniz Universität Hannover

GaAs/AlGaAs heterostructures, with the two-dimensional electron gas being located in GaAs single quantum wells, were grown using the molecular beam epitaxy technique. Beside the modulation-doping, additional homogeneous Si-doping of the quantum well was performed, the Si-atoms in the quantum well acting as impurity scattering sites. The samples differ by the density of the incorporated Si-atoms. The quantum well of the reference sample was left undoped, reflecting the unintentional background impurity. Transport measurements were performed on the samples for a wide range of temperatures. For the reference sample we found a high mobility µ = 2 x 10⁶ cm²/Vs. For increasing additional impurity density we found a drastic decrease of the mobility down to 1 x 10⁴ cm²/Vs. All samples exhibit parabolic magnetic field dependence at low magnetic fields and low temperatures, attributed to electron-electron interaction. A narrow peak around zero magnetic field in the samples with additional impurity is attributed to weak localization. The differences in the magnetoresistance curves are analyzed in detail in order to study the direct influence of the impurity density on the magnetotransport in 2DEG systems