Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 15: Focussed Session: Geometry- and Topology-Controlled Nanoarchitectures I
HL 15.9: Talk
Tuesday, March 13, 2018, 12:00–12:15, EW 015
Topologically Distinct Semiconductor Nanostructures by Droplet Epitaxy — •Stefano Sanguinetti1,2, Francesco Biccari3, Sergio Bietti1, Anna Vinattieri3, Alexey Fedorov2, and Massimo Gurioli3 — 1L-NESS and University of Milano Bicocca, Via Cozzi 55, 20126 Milano, Italy — 2IFN-CNR, Via Anzani 42, 22100 Como, Italy — 3University of Florence and LENS, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy
Extremely complex semiconductor quantum nanostructures, constituted by multiple concentric rings, disks and dots can be designed and realized by Droplet Epitaxy. Topology induced effects determines the electronic and optical properties of these nanostructures. In particular, carrier dynamics appears to be related to topology induced selection rules. We present in detail the droplet epitaxy growth procedure and the analysis of the emission of individual GaAs/AlGaAs complex nanosystems composed by concentric and topologically distinct quantum nanostructures. Time resolved, temperature and excitation power density dependence of the photoluminescence from single and ensemble nanostructures have been used in order to determine the carrier dynamics. Despite the small spatial separation between the dot and the ring, the exciton dynamics in the nanostructures is completely decoupled at low temperatures. At higher temperatures it is possible observe a clear change in the carrier dynamics, which shows the onset of the coupling between the nanostructures. Electronic structure calculations show that the interaction takes place via a delocalized common excited energy state.