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HL: Halbleiterphysik

HL 39: Symposium: Quanten Hall Systeme

HL 39.3: Fachvortrag

Freitag, 26. März 1999, 10:30–11:00, H1

Spatially resolved measurements near the breakdown of the quantum Hall effect — •Georg Nachtwei, Ismet Kaya, Klaus von Klitzing, and Karl Eberl — Max-Planck-Institut f"ur Festk"orperphysik, Heisenbergstr. 1, D-70569 Stuttgart

We have analyzed the generation and relaxation of hot electrons

along their drift direction near the breakdown of the quantum

Hall effect. The dissipative resistivity of the two-dimensional

electron system (2DES) is measured as a function of the distance

from the electron injection. By injecting hot electrons into a

Hall bar at subcritical currents, the relaxation process was

analyzed. The inelastic relaxation length was found strongly

correlated with the elastic mean free path. Thus, we conclude

that the relaxation is triggered by Coulomb scattering.

The injection of electrons at supercritical current levels

allowed to monitor the evolution of the breakdown along the drift

direction. After a linear increase of the resistivity with the

drifting distance, a rather steep increase of of dissipation

occurs. The linear increase is attributed to a constant tunneling

rate between Landau levels, whereas the steep increase is likely

due to an avalanche-like multiplication of hot electrons.