Femtosecond dynamics of resonantly excited room-temperature excitons in II-VI CdZnTe/ZnTe quantum wells

Abstract

The femtosecond pump-and-probe technique, with 14-fs probe pulses, was used to measure exciton dynamics utilizing the unique characteristics of II-VI CdZnTe/ZnTe quantum wells, at room temperature. We have found that the bleaching effect of ``cold'' neutral excitons on excitons is stronger than that of the same density of ``cool'' uncorrelated charged electron-hole pairs, in disagreement with predictions. We find strong evidence, however, that long-range Coulomb screening is negligible in quasi-2D quantum wells. Additionally, we have measured a very fast exciton ionization time of 110 fs.