Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 76: Heterostructures
HL 76.3: Talk
Thursday, March 29, 2012, 10:00–10:15, EW 202
Control of the population decay time in submonolayer-stacks by spatial coupling to Stranski-Krastanow-QDs — •Thomas Switaiski1, Jan-Hindrik Schulze2, Tim David Germann2, André Strittmatter2, Udo W. Pohl2, Dieter Bimberg2, and Ulrike Woggon1 — 1Inst. f. Optik und Atomare Physik, TU Berlin, Germany — 2Inst. f. Festkörperphysik, TU Berlin, Germany
Superlattices of submonolayer depositions (SML-stack) based on InAs/GaAs provide high power conversion efficiencies and low threshold current densities when used as an active medium in laser diodes. In addition, these SML-stacks offer controllable tuning parameters.
Here, an approach to introduce an additional parameter to control the properties of a SML-stack is presented. We investigated the impact of coupling between a SML-stack and a Stranski-Krastanow (SK) grown quantum dot layer, as this coupled nanostructured system offers further parameters to control the decay dynamics. The studied samples contain one layer of InGaAs-SK-QDs, which is overgrown with the matrix material GaAs of a defined thickness d, followed by an InAs/GaAs-SML-stack. The presence of the energetically lower SK-QDs introduces an additional, nonradiative decay channel to the carriers inside the SML-stack. Hence, the decay time for the SML-luminescence is dependent on the vertical distance between the two different nanostructures.
We present time-resolved photoluminescence measurements and a model of a conventional rate equation system to simulate the observed data and to approximate the coupling time constant of the SML-stack to the SK-QDs.