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HL: Fachverband Halbleiterphysik

HL 32: Quantum dots and wires: preparation and characterization I

HL 32.6: Talk

Wednesday, February 27, 2008, 15:30–15:45, ER 270

Influence of the deposition rate on the InP quantum dot formation in Al_0.20GaInP barriers — •Bjoern Jakobi — Universität Stuttgart, IHFG, Institut für Halbleiteroptik und funktionelle Grenzflächen, Allmandring 3, 70569 Stuttgart, Germany

The preconditions for high efficient quantum dot (QDs) devices and single photon emitters are high luminescence efficieny at elevated temperatures. We examine InP QDs capped Al_0.20GaInP barriers in order to achive these requirements for the red spectral range.
Major influence for the temperature stability can be attributed to band offsets between the barrier and the QDs, the confinement energy. This is mainly influenced by deposition parameters like the growth time and the growth rate of the InP QDs. In our experiment we hold the total amount of material of 2.1 monolayers (ML) constant and vary the growth rate between 2.1 ML/s and 0.525 ML/s. The samples in this series were grown at 650 ^∘C to avoid Al incorporation into the dots. The dots were capped by 30 nm Al_0.20GaInP barriers.
The spectral analysis was done with photoluminescence (PL) measurements. Further we show the influence of the growth rate on the power and temperature dependent behavior of our structures by time-resolved and quasi continous PL-measurements with a pulsed Ti-Saphire laser.
With these methods we deduced the confinement energy and differ the wetting layer from dots. The samples show a temperature stability to 80 K partly up to 90 K. Allthough a bimodal size distribution of the dots could have been expected, the presented series shows only small A-type QDs.