Spectroscopies of exciton and biexciton in InGaAs quantum disk

Exciton in isolated InxGa1-xAs quantum disk was studied by probing single-d ot photoluminescence. Each of the excitonic emission was found to be excite d via a number of sharp-excited state resonances, thereby the discrete dens ity of state and long-lived phase coherence of the states were proven. A si gnificant contribution of the biexciton excitation was found to enable two- photon absorption, making optical excitation process complex. It leads to a dynamic quantum mechanical interference in the excitation via exciton/biex citon states. (C) 2000 Elsevier Science B.V. All rights reserved.