Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 79: Quantum dots and wires IV

HL 79.3: Talk

Friday, March 20, 2020, 10:00–10:15, POT 151

Towards photocurrent monitoring of single photon emitters — •Sebastian Krehs, Björn Jonas, Alex Widhalm, Kai Spychala, Timo Langer, Dirk Reuter, and Artur Zrenner — Physics Department, Paderborn University, Warburger Straße 100, 33098 Paderborn, Germany

In the past photocurrent (PC) detection of single quantum dot excitons was limited to the regime of high tunnelling rates and elevated excitation powers, which results for π-pulse excitation in currents in the 10 pA-range. Refined PC detection enabled us to improve the sensitivity down to the fA-range. This allows for ultrasensitive photocurrent detection in the regime of single photon emission and leads to a new concept for the frequency stabilization of single photon emitters.
In this work we have fabricated Schottky photodiodes with embedded high quality MBE grown InAs/GaAs QDs. We have been able to demonstrate exciton ground state linewidths as low as 1.62 µeV by electrically detected laser spectroscopy. Our results are close to the Fourier transform limit of QD systems [1]. Extremely weak electric detection of the resonance position of a single photon emitter is possible down to a regime, where only 0.2% of the excitation is extracted by charge separation. To utilize this, we need to realize a seamless electric field induced transition from the PC- to the PL-regime, which avoids the formation of charged states. To achieve this, we performed band structure engineering for the symmetrisation of electron and hole tunnelling rates.

[1] A.V. Kuhlmann et al. Nature Physics 9, 570-575 (2013)