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The growth kinetics of CdTe colloidal nanocrystals has been analyzed quantitatively by means of dynamic light scattering and photoluminescence measurements. The growth rates, size distributions, critical radii, and diffusion constants have been calculated in the framework of the Sugimoto theoretical model. A two-step diffusion-controlled growth regime has been proposed for the reported synthesis and a set of relations for the time evolution of the size distribution has been derived and discussed in the sense of the size distribution focusing concept.

Photoluminescence (PL) measurements as a function of temperature and excitation intensity were carried out in a sample containing two InGaAs∕InAlAs superlattices, grown on the same InP substrate, with quantum wells and barriers of different widths. The fluctuations in the confinement potential for excitons in both structures are investigated by following the blueshift of the PL peaks with increasing temperature as well as with rising excitation intensity, at low temperatures. A decrease in the full width at half maximum of the PL peaks with increasing excitation power was also observed. The change in the PL linewidth with excitation power is interpreted in terms of the variation of the relative contribution of the excitons localized at the excitonic band tail (due to the potential fluctuations) and of the nonlocalized excitons. Moreover, the activation energies of the nonradiative channels responsible for the thermal quenching of the photoluminescence peaks are deduced from an Arrhenius plot of the integrated PL intensity.

A method based on the unidimensional gain equation has been developed in order to fit the experimental data due to amplification of spontaneous emission in a thin film of conjugated polymer waveguide. The results have confirmed not only a dependence of the gain coefficient on the laser intensity but also on the length of the excitation laser stripe. The results are presented as a function of the average intensity in W/cm2, which is a manner to express the threshold intensity for a direct comparison between different materials, independent of the setup used.