Berlin 2005 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 57: Poster IIa
HL 57.26: Poster
Dienstag, 8. März 2005, 16:30–19:00, Poster TU E
High resolution photocurrent-spectroscopy of a single quantum dot — •Patrick Ester1, Stefan Stufler1, Artur Zrenner1 und Max Bichler2 — 1Universität Paderborn, Warburger Straße 100, D-33098 Paderborn, Germany — 2Walter Schottky Institut, Technische Universität München, Am Coulombwall, D-85748 Garching, Germany
We report on high resolution photocurrent spectroscopy of a single quantum dot. Our attention applies to the two-level character of a single InGaAs/GaAs quantum dot, defined by the ground state exciton. With high resolution photocurrent spectroscopy we analyze the behaviour of a single quantum dot under cw-excitation. Experiments include linewidth, power-broadening and saturation analysis. In the limit of low optical excitation we observe a ground state linewidth down to 4 µeV. With increasing excitation intensities the linewidth shows a characteristic power broadening. This effect is a direct consequence of the saturation of the absorption in a two-level system under conditions of high excitation intensities. Due to the high resolution we further are able to measure the excitonic fine structure splitting. The results of the cw-excitation experiments indicate an almost perfekt quantum mechanical two-level system. This can be taken as a basis for coherent manipulations of the quantum dot, important for possible applications in quantum information processing.