Excitonic complexes in InGaAs/GaAs quantum dash structures

Optical properties of single self-assembled InGaAs/GaAs quantum dashes have been investigated. The excitation power dependent measurements together with the rate equation model calculations enable to identify the excitonic and biexcitonic emission from one quantum dash. Based on that the biexciton binding energy and the relative exciton to biexciton lifetime ratio have been estimated. The emission spectra have also revealed a fingerprint of Coulomb interaction between excitons confined in the quantum dash and adjacent wetting layer. The conditions required for observing this phenomena and the influence of the wetting layer on the emission of individual quantum dashes have been discussed.