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HL: Fachverband Halbleiterphysik

HL 64: Poster II

HL 64.14: Poster

Donnerstag, 19. März 2020, 10:00–13:00, P1A

Electric field dependence of the biexciton decay in a single quantum dot — •Björn Jonas, Sebastian Krehs, Alex Widhalm, Kai Spychala, Timo Langer, Dirk Reuter, and Artur Zrenner — Physics Department, Paderborn University, Warburger Straße 100, 33098 Paderborn, Germany

The decay of biexcitons in single quantum dots is commonly used to generate polarization entangled photon paires. In order to gain control over the emission energy, the QDs are often embedded in diode structures. This allows for tuning via the quantum confined stark effect. Aside from the beneficial effect of energy tuning, the applied electric fields can also induce single particle tunneling and hence charging of the QD. Both effects can decrease the efficiency of quantum light sources.
In this work we studied the decay of biexcitons in a single QD embedded in a symmetric PIN-diode. We resonantly excited the biexciton-state via 2-photon absorbtion with a cw-laser and observed its optical decay depending on the applied electric field. This data was then compared with electric field dependend photocurrent measurements.
We find that under forward bias the intensities of the XX- and X-emission are equaly affected by negative charging of the QD. Under reverse bias the X-emission is selectively decreased by tunneling. Furthermore the faster tunneling rate of the electrons leads to the generation of positivly charged excitons, which is clearly detected by an emerging trion line. Based on these results we propose a tailored sample structure, that symmetrises the tunneling times of electrons and holes and therefore increases the efficiency of the light source.