We present excitation-pulse-width- and pump-power-dependent microelectroluminescence and photon statistics measurements on electrically driven single-photon devices based on InP/AlGaInP quantum dots (QDs). For an excitation regime far below QD saturation, the results show a characteristic decrease of the purity of the single-photon emission [g(2)(0) value] with increasing excitation pulse width. For stronger excitation pulses close to QD saturation, strong antibunching is maintained for a much larger pulse width. In this case the ground-state exciton emission, which is used for the single-photon source, is inhibited during the pump pulse due to the presence of higher excited states. This prevents multiple-ground-state emission and reexcitation during long pump pulses and delays the single-photon emission to the end of the pulse, as predicted by theory and confirmed experimentally.
Publication: Strong antibunching from electrically driven devices with long pulses: A regime for quantum-dot single-photon generation
C. A. Kessler, M. Reischle, F. Hargart, W.-M. Schulz, M. Eichfelder, R. Roßbach, M. Jetter, and P. Michler P. Gartner, M. Florian, C. Gies, and F. Jahnke 
Phys. Rev. B 86, 115326 (2012)
Contact person: Prof. Peter Michler