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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