Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

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

HL 32.13: Talk

Wednesday, February 27, 2008, 17:30–17:45, ER 270

Growth of Sub-Monolayer Quantum Dots by MOCVD — •Franziska Luckert, Konstantin Pötschke, Till Warming, and Dieter Bimberg — Technical University of Berlin, Institute of Solid State Physics, Sekr. EW 5-2, Hardenbergstr. 36, D-10623 Berlin, Germany

Sub-monolayer (SML) deposition is an alternative approach for the self-organised formation of quantum dots (QDs) different from the Stranski-Krastanow growth mode. The deposition of a SML InAs on GaAs (001) surface results in the formation of distinct monolayer (ML) high InAs islands which influence, after overgrowth with GaAs, the deposition of the next SML by non-uniform lateral strain.

In this study the growth of the SML QDs was done by metal-organic chemical vapour deposition. Several samples with varying: -thickness of the GaAs spacer, -amount of InAs (< 1 ML) and -number of repetitions of InAs/GaAs cycles were grown and examined with Photoluminescence (PL) at 10K. The emission wavelength was observed to be tuneable from 900 to 1000 nm, depending on the growth parameters. The peaks observed in the PL spectra are characterised by a very small full width at half maximum of 4-12 meV. The detailed mathematical analysis of the line shape of these peaks yields that the SML heterostructures can be described as a quantum-dot in a quantum-well structure. This implies that there are regions with a high In concentration in a lower In-content quantum well which show a Gaussian PL shape.