Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 12: Poster I
HL 12.49: Poster
Montag, 8. März 2004, 16:30–19:00, Poster A
Breakdown of the quantum Hall effect in samples with intentionally introduced defects — •Dorina Diaconescu, Sascha Hoch, Dirk Reuter, and Andreas Wieck — Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Germany
We study the role of electron scattering on the onset of the quantum Hall effect breakdown in 2-dimensional electron systems with intentionally introduced defects. The defects are Ga ions or vacancies in the crystal lattice introduced by focused ion beam (FIB) implantation. The defects can be introduced lateral homogenously, over the whole area of the Hall-bar, or with spatial resolution. The dependence of the breakdown current as a function of defect density was investigated in samples with a lateral homogenous implantation. For low implantation doses, the critical current increases with the ion dose. Further increase of the ion dose leads to a reduction of the critical current. The results confirm the work of Nachtwei et al. [1], where antidot arrays have been patterned on the GaAs/AlxGa1−xAs heterostucture. The initial increase of the critical current with the ion dose can be explained by an increased inelastic scattering rate at the defects. It results a more effective cooling of the hot electrons. Higher defect densities increase the impurity-assisted inter-Landau level transitions, and a significant decrease of the critical current is observed.
[1] G. Nachtwei, G. Lütjering, D. Weiss, Z. H. Liu, K. von. Klitzing, and C. T. Foxton, Phys. Rev. B. 55, 6731 (1996).