Dynamics of highly excited charge carriers in CdS nanocrystallites embedded into ZrO2 films

Transient grating experiments were performed at room temperature in CdS nanocrystallites (nc) embedded into ZrO2 sol–gel films. The dynamics of photo-generated carrier showed to depend on the excitation intensity. Relaxation of non-equilibrium charge carriers take place through two channels: electron–hole recombination in nanocrystallite volume and nanocrystallite/ZrO2 matrix surface states. At higher intensities a saturation of the excited surface states occurs simultaneously with the carrier heating. Systematic increase of the carrier lifetime is observed with the nc size.