Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 60: Quantum dots: Optical properties I (with TT)

HL 60.5: Talk

Wednesday, April 2, 2014, 10:30–10:45, POT 251

Deterministic fabrication of quantum-dot microlenses for enhanced photon extraction efficiencies — •Manuel Gschrey, Marc Seifried, Luzy Krüger, Jan-Hindrik Schulze, Tobias Heindel, Sven Rodt, André Strittmatter, and Stephan Reitzenstein — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, D-10623, Germany

The realization of building blocks for long-distance quantum communication is a major driving force for the development of advanced nanophotonic devices, like efficient quantum-dot-based single-photon sources. One major challenge of a deterministic device fabrication using self-assembled quantum dots (QDs) results from their random growth, which reduces the yield of usable nanophotonic devices. Another issue is the low extraction efficiency (EE), due to the high refractive index of the surrounding semiconductor material, where total internal reflection at the surface occurs already for very small angles. To overcome these obstacles we apply a recently developed cathodoluminescence (CL) lithography technique [1] to fabricate and position microlenses on top of preselected single InGaAs QDs. This in-situ lithography technique is based on low-temperature CL spectroscopy, to identify the spectral features and spatial positions of the statistically grown QDs, prior to the lithography step. To obtain optimum EE, the position and shape of the lens is directly taylored in the CL-system by means of 3D electron-beam lithography. By using this technique we fabricated microlenses that allow for a sixfold increase in EE as compared to plain surfaces - [1] M. Gschrey et al., APL 102, 251113 (2013).