Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 15: Focussed Session: Geometry- and Topology-Controlled Nanoarchitectures I

HL 15.3: Talk

Tuesday, March 13, 2018, 10:00–10:15, EW 015

Observation of Aharonov-Bohm oscillations in core-shell nanowire crystal-phase quantum rings — Pierre Corfdir¹, •Oliver Marquardt^1,2, Ryan B. Lewis¹, Chiara Sinito¹, Manfred Ramsteiner¹, Achim Trampert¹, Uwe Jahn¹, Lutz Geelhaar¹, Oliver Brandt¹, and Vladimir M. Fomin³ — ¹Paul-Drude-Institut für Festkörperelektronik — ²Weierstraß-Institut für angewandte Analysis und Stochastik — ³Leibniz-Institut für Festkörper- und Werkstoffforschung

Coherence in nanostructures is at the heart of a wide range of quantum effects such as Josephson oscillations between exciton-polariton condensates in microcavities, conductance quantization in one-dimensional ballistic transport, or the excitonic Aharanov-Bohm (AB) effect in quantum ring (QR) devices. However, inevitable interface roughness in self-assembled low-dimensional semiconductor heterostructures usually leads to loss of coherency and charge carrier localization. The study of AB oscillations in semiconductor QRs has thus required the fabrication of heterostructures with high interface quality, and has so far been limited to self-assembled ring structures with very limited control of shape and dimension or to nanorings that were fabricated by nanolithography. We demonstrate that core-shell GaAs/AlAs nanowires containing atomically flat polytype segments can be systematically tailored for studies of the excitonic AB effect of neutral and charged excitons. Thanks to their atomically flat interfaces and the absence of alloy disorder, phase coherence is preserved even in QRs with diameters on the order of 90 nm.