Population dynamics of resonantly excited carriers in InAs quantum dots

Summary form only given. There is intense current interest in the dynamical properties of self-organized InAs quantum dots from fundamental and applied viewpoints. We report here measurement and analysis of the depopulation dynamics of the lowest electronic states following resonant excitation by a femtosecond pulse. Our results, obtained by using a high-sensitivity differential transmission technique that allows measurement of differential transmission as low as 10/sup -7/, provides the first direct information on the thermal activation rates of carriers in quantum dots. The results show that thermal activation by phonon absorption is an efficient process at room temperature and strongly argue against phonon-bottleneck effects.