Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 14: Poster II

HL 14.20: Poster

Monday, March 18, 2024, 15:00–18:00, Poster F

Circular gratings for efficient light extraction from InAs quantum dots — •Frederik Ernst¹, Stefan Linden¹, Paul Steinmann¹, and Beata Kardynal² — ¹Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany — ²PGI-9, Forschungszentrum Jülich, Jülich, Germany

Indium arsenide quantum dots are recognized as high-quality single photon sources. Since the quantum dots are however, embedded in a high refractive index material (GaAs), efficient outcoupling of the photons is challenging. In order to increase the efficiency of light extraction from the GaAs host, we investigate circular gratings (bullseye structure) made from tantalum pentoxide that are positioned on the GaAs surface above individual quantum dots. Our approach involves optimizing the design of these bullseye structures through numerical calculations based on the Finite-Difference-Time-Domain (FDTD) method. The production of these structures, targeted at selected quantum dots, is achieved using electron beam lithography with a positive-tone resist, followed by electron beam evaporation to deposit a 70 nm thick tantalum pentoxide film. Optical experiments conducted at liquid helium temperatures (T=4 K) include exciting the quantum dots with a 785 nm wavelength laser and recording their PL emission before and after bullseye deposition. Preliminary analysis suggests an enhancement in light extraction efficiency, indicating promising applications in quantum dot technologies for improved photonics systems. Ongoing analysis aims to quantify this increase, potentially offering a significant advancement in photon manipulation at the quantum level.

Keywords: Quantum dots; Point-like light source; Nano structures