Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 74: Quantum dots: Optical properties
HL 74.5: Vortrag
Donnerstag, 14. März 2013, 10:30–10:45, H16
Spectroscopy on single buried InAs quantum dots by scattering scanning near-field infrared microscopy — •Markus Fehrenbacher1, Rainer Jacob1, Stephan Winnerl1, Jayeeta Bhattacharyya1, Harald Schneider1, Marc Tobias Wenzel2, Hans-Georg von Ribbeck2, Lukas M. Eng2, Paola Akinson3, Oliver G. Schmidt3, and Manfred Helm1 — 1Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 2TU Dresden, Dresden, Germany — 3Leibniz Institute for Solid State and Materials Research, Dresden, Germany
Quantum dots are a highly interesting material system for many application purposes such as single photon emitters in the near-infrared, but also for mid- and far-infrared applications. Studying the linewidth of involved optical transitions offers valuable clues to the dephasing mechanisms of the trapped electrons. However, due to size fluctuations of the quantum dots, inhomogeneous broadening of the signals usually hides this information when investigating ensembles of dots. Therefore, single-dot spectroscopy has to be performed for this purpose. In contrast to studies of interband transitions this is not well established at all for intersublevel transitions. In this work, scattering type scanning near-field optical microscopy (s-SNOM) in combination with a free-electron laser is used to investigate intersublevel transitions in single self-assembled buried InAs quantum dots. Thereby, spectrally resonant optical contrast to the surrounding GaAs substrate is observed at photon energies of 83 meV and 123 meV, which can clearly be assigned to the s-d and p-d transitions of single conduction band electrons.