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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.60: Poster

Montag, 27. März 2023, 13:00–15:00, P2/EG

Investigation of the biexciton decay in semiconductor In(Ga)As/GaAs quantum dots — •Christopher Buchholz, Sebastian Krehs, and Artur Zrenner — Universität Paderborn, Paderborn, Deutschland

The biexciton-exciton cascade is a widely used promising emission mechanism in quantum dots for generating entangled photon pairs with high fidelity. An often overlooked critical parameter for the quality of the emitted photons is the different lifetimes of electron and hole. Since the lifetimes of excitonic states can be influenced via external electrical fields (quantum confined stark effect), we studied this parameter in Schottky-contacted GaAs heterostructures. We approached this challenge by placing the quantum dots at different distances to the n-contact, 40 nm and 80 nm, respectively. The quantum dots were first characterized by voltage-dependant photoluminescence (PLV) measurements under above-band excitation and further investigated by photocurrent spectroscopy (PC) under resonant excitation and PLV under two-photon excitation (TPE). From the resonances in the PC measurements, the electron lifetime was extracted, whereas the TPE measurements showed the occurrence of the biexciton and charged exciton states as a function of the voltage. The results suggest that an increased distance to the n-contact leads to a decreased tunneling rate of electrons into the quantum dot. At the same time, the tunneling from the quantum dot is not affected.