Spatial evolution of the generation and relaxation of excited carriers near the breakdown of the quantum Hall effect

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• 作者：Kaya ; I.I. ; Nachtwei ; G. ; Sagol ; B.E. ; von Klitzing ; K. ; Eberl ; K.
• 关键词：73.50.Fq ; 73.40.Hm ; 72.10.Fk ; Quantum Hall effect ; Breakdown ; Hot-electron generation and relaxation
• 刊名：Physica E
• 出版年：2000
• 出版时间：February, 2000
• 年：2000
• 卷：6
• 期：1-4
• 页码：128-131
• 全文大小：95.2 K

文摘

We have measured the generation and relaxation of excited carriers along their drift direction near the breakdown of the quantum Hall effect (QHE). The dissipative resistivity ρ_xx(x) at current densities close to the critical value for the QHE breakdown was measured as a function of the distance x from the electron injection at x=0. By injecting “cold” electrons into constrictions at supercritical current levels, the evolution of the breakdown along the drift direction was monitored. After a smooth increase of the resistivity with the drifting distance, an avalanche-like rise towards a saturation value occurs. Drastic changes of the resistivity profiles with the applied current were found in a narrow range around the critical current. The observed behavior is attributed to impurity-assisted tunneling between Landau levels. By injecting hot electrons (excited in a periodic set of constrictions) into a region with subcritical current density, the relaxation process was analyzed. Inelastic relaxation lengths with typical values in the range from 0.3 to 4 μm were found, which agree within 10 % with the elastic mean free path determined from the Hall mobility at zero magnetic field. We conclude that the energy relaxation process is triggered by scattering at impurity potentials.