E. Vanagas et al., DYNAMICS OF OPTICAL NONLINEARITIES INDUCED BY STRONG LIGHT ILLUMINATION IN CDS NANOCRYSTALLITES, Journal of applied physics, 81(8), 1997, pp. 3586-3591
Light induced grating experiments have been performed at room temperat
ure in CdS nanocrystallites of 2.5 nm radius embedded in sol-gel glass
films of different semiconductor volume concentration. The dynamics o
f tile photogenerated carriers at the lowest transition peak has been
shown to depend on the excitation intensity, No spatial diffusion is o
bserved up to a nanocrystallite volume concentration of 35%. Below a f
ew MW/cm(2) the carriers relax in each nanocrystallite, either radiati
vely in similar to 150 ps or by trapping the electrons 15 meV below th
eir excitation transition. For higher intensities of excitation, a sat
uration of the excited stales occurs which allows the electrons to be
trapped in the glass matrix, inducing a permanent grating by the creat
ion of a static electric field. (C) 1997 American Institute of Physics
.