Temperature evolution of the photoexcited charge carriers dynamics in Ge/Si quantum dots

摘要

The kinetics of the photoinduced mid-infrared intraband hole absorption after the short interband excitation pulse has been studied in an dense array of surfactant-mediated Ge/Si(001) quantum dots. Absorption decay curves reveal two processes characterized by fast and slow decay times at low temperatures. A specific temperature evolution of the absorption transients was observed with the increase in temperature. A model of charge carrier kinetics has been developed based on the rate equation analysis. Measured transient characteristics of charge carriers are well described within this model. The energetic gap between two conduction band electron states within the quantum dots and the valence band energetic barrier at the quantum dot interface have been evaluated.