Biexcitonic fingerprint in the nondegenerate four-wave-mixing signal of weakly confined cadmium sulfur quantum dots.
Nondegenerate four-wave mixing is analyzed with respect to biexcitonic contributions in the third-order nonlinear susceptibility x((3)) . The presence of biexcitons causes a distinct asymmetry in the frequency dependence of self-diffraction. By measurement of the dependence of the intensity of the self-diffracted signal on detuning between the two incident laser beams, the biexciton binding energy is determined to be E(XX)=7.8 meV for cadmium sulfur quantum dots of R=7.5 nm embedded in glass. Thus, even for weakly confined II-VI quantum dots with R~2.7a(B) , a confinement-induced enhancement of E(XX) was found.
Spöcker
H
H
Portuné
M
M
Woggon
U
U