Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 78: Quantum dots: Preparation and characterization

HL 78.4: Vortrag

Mittwoch, 2. April 2014, 17:15–17:30, POT 251

Fabrication of a charge-tunable GaAs/AlGaAs strain-free quantum dot device suitable for single dot spectroscopy — •Fabian Langer, David Plischke, Martin Kamp, and Sven Höfling — Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany

Stranski-Krastanov growth has been the method of choice for the fabrication of high-quality self-assembled quantum dots in a variety of material systems. The difference in lattice constants that drives the self-organization of the dots is absent in the GaAs/AlAs material system. Therefore, other approaches like modified droplet epitaxy (MDE)1 have to be used for producing GaAs QDs on AlGaAs. This process creates QDs without significant material intermixing and allows the investigation of exciton fine-structure splitting or nuclear spin dynamics without the influence of strain or piezoelectric effects. In this contribution we report on the fabrication of a charge-tunable GaAs/AlGaAs QD device containing QDs deposited by MDE. We achieved a QD density in the low 109 1/cm2 range, enabling the use of single dot spectroscopy without any additional patterning. The observed linewidths are as small as 40 µeV. We were able to charge a single QD with up to four electrons in devices with a Schottky gate. The QD character of the photoluminescence (PL) emission was proven by photon anti-bunching and cross-correlation measurements yielding a g(2)(0) value of 0.05.

[1] Watanabe, K.; Nobuyuki, K.; Gotoh, Y. Jpn. J. Appl. Phys., Vol. 39, L79-L81, 2000

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