Pauli blocking dynamics in optically excited quantum dots: A picosecond excitation-correlation spectroscopic study

Abstract

State-filling dynamics in self-assembled InAs/GaAs quantum dots (QDs) is studied through their steady-state photoluminescence (PL) using a variant of picosecond excitation-correlation (EC) spectroscopy. Steady-state PL showed an interesting transition from bimolecular recombination at low-excitation fluence to excitonic recombination at higher fluence. As for the EC signal, while the ground-state response is always snubbed when the two excitation pulses are temporally nearly coincident, the excited-state response can either be enhanced or reduced, depending on the excitation fluence. The time evolution of this response is studied for the first three levels in a QD ensemble. A minimal theoretical model, which combines carrier loss kinetics with the principle of detailed balance and the Pauli exclusion principle, quantitatively reproduces the observations.

Distinguishing quantum dot-like localized states from quantum well-like extended states across the exciton emission line in a quantum well

“…This way of defining ECPL signal is different from the usual definition of ECPL signal found in the literature [18][19][20] but is simpler to interpret. 16 We measured PL spectra at different delays using high resolution CCD-spectrograph and calculated ECPL spectra numerically from the stored PL spectra. Details of our experimental scheme was described in Ref.…”

“…Details of our experimental scheme was described in Ref. 16. This method, giving high spectral resolution, is different from the conventional ECPL measurements where the two beams incident on the sample are chopped (modulated) at different frequencies and the emitted PL signal (after being spectrally dispersed) is measured with a point detector at the sum or difference frequency, one wavelength at a time.…”

“…In this work we use a variant of the picosecond time-resolved excitation-correlation photoluminescence 16 (ECPL) spectroscopy to determine the location of the exciton mobility edge in a high-quality GaAs/AlGaAs multi-quantum wells (MQWs) sample. This is a new and simple way of experimentally locating the mobility edge.…”

Influence of the Pauli exclusion principle on scattering properties of cobosons

“…al. 47 who investigated the dynamics of state-filling dynamics in self-assembled InAs/GaAs quantum dots (QDs) using picosecond excitation-correlation (EC) spectroscopy. The action of the Pauli exclusion principle appeared visible in the photoluminescence results 47 .…”

“…47 who investigated the dynamics of state-filling dynamics in self-assembled InAs/GaAs quantum dots (QDs) using picosecond excitation-correlation (EC) spectroscopy. The action of the Pauli exclusion principle appeared visible in the photoluminescence results 47 . Future experimental works may wish to examine the controlled scattering of excitons which occupy specific Schmidt modes, and the subsequent emission of phonons with a desired range of energies.…”