Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 48: Quantum dots and wires: preparation and characterization II

HL 48.2: Talk

Thursday, March 29, 2007, 16:30–16:45, H13

InP-quantum dots: Towards high temperature emission — •Wolfgang-Michael Schulz, Robert Roßbach, Michael Jetter, Matthias Reischle, Gareth Beirne, and Peter Michler — Institut für Strahlenphysik, Allmandring 3, 70569 Stuttgart, Germany

To increase the carrier confinement and luminescence at elevated temperatures for InP-quantum dots, we embedded them in Al_0.50Ga_0.50InP. Atomic force microscope measurements are showing a bimodal size distribution of uncapped samples, which can also be seen in the photoluminescence measurements. From time-resolved, power- and temperature-dependent PL measurements, we could deduce a confinement energy of 274 meV for small A-type dots and 572 meV for bigger B-type dots. Therefore, the temperature where the thermal reemission of the carriers out of the dots dominates, could be estimated to 160 K for A-type, respectively 250 K for B-type dots. The sample also shows a thermally induced, wetting layer assisted carrier transfer between these bimodal dots, increasing the luminescence intensity of the A-type dots at elevated temperatures. A further increase of the luminescence at elevated temperatures was achieved by placing the QD layer on top of a DBR structure. On account, luminescence up to 460 K was observable. The zero-dimensional behavior was verified with high resolution µ-PL and autocorrelation measurements, showing single photon emission at 4 K.