Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 34: Joint Session: Solid State Photon Sources
HL 34.4: Talk
Tuesday, March 15, 2011, 11:30–11:45, HSZ 02
Near-field infrared spectroscopy of single InAs quantum dots — Rainer Jacob1, •Stephan Winnerl1, Harald Schneider1, Manfred Helm1, Marc Tobias Wenzel2, Hans-Georg v. Ribbeck2, and Lukas M. Eng2 — 1Institut für Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden-Rossendorf, Postfach 51 01 19, 01314 Dresden, Germany — 2Institut für Angewandte Photophysik, TU Dresden, George-Bähr-Straße 1, 01069 Dresden, Germany
Scattering-type scanning near-field optical microscopy (s-SNOM) is a versatile technique in optical sciences. It provides optical resolution in the nanometer range, while offering spectroscopic application when combined with a tunable light source. Here, we exploit the combination of a s-SNOM with a widely tunable free-electron laser. With this setup, we were able to perform optical spectroscopy of single InAs quantum dots by means of their near-field signature in the mid infrared. The sample was composed of a single layer of self-assembled InAs quantum dots that were capped by a 70 nm thick GaAs layer. In the s-SNOM-measurements we could obtain a clear near-field contrast between the dots and the surrounding medium at 10.2 um which corresponds to 120 meV. Another clear contrast could be obtained for 85 meV. Both signatures could be attributed to intersublevel transitions in the quantum dot [1]. To our knowledge this is the first time that an optical near-field signature of an intersublevel transition could be demonstrated at a single InAs quantum dot.
[1] P. Boucaud et al., C. R. Physique 9, 840 (2008)