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TT: Fachverband Tiefe Temperaturen

TT 33: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 2

TT 33.7: Vortrag

Donnerstag, 25. März 2010, 15:30–15:45, H19

An electron avalanche amplifier in a two-dimensional electron system — •Daniela Taubert¹, Georg Schinner¹, Hans-Peter Tranitz², Werner Wegscheider³, and Stefan Ludwig¹ — ¹Center for NanoScience and Fakultät für Physik, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 München, Germany — ²Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg, Germany — ³Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland

A biased quantum point contact - a device that is widely used as detector of single electrons in quantum dot circuits - and its back-action on the quantum dots can only be fully understood if the relaxation mechanisms of the excited hot electrons emitted into its leads are known. We therefore study the behavior of hot electrons in two-dimensional mesoscopic structures, thereby considering a wide range of electron energies.

We observe scattering of excited charge carriers with the degenerate Fermi sea in a three-terminal device. Amplification of the injected electron current can be achieved by energetically separating the electrons excited from the Fermi sea from the conduction band holes they leave behind by means of a barrier. The observed amplification effect depends on the energy of the injected electrons, the injected current, and the height of the barrier used for separating electrons and holes. Our analysis is based on an energy-dependend electron-electron scattering length as well as neutralization of holes.