Bandfilling and bandgap shrinkage in the femtosecond spectroscopyof GaAs

摘要

Abstract: The effects of bandfilling and bandgap shrinkage in the femtosecond absorption saturation measurements of GaAs have been studied using femtosecond pulses generated from CPM dye laser and self-mode-locked Ti:sapphire laser. For exciting photon energy of 2 eV and carriers density of 1 by 10$+18$/ cm$+$MIN@3$/, an optical induced absorption increase is observed and is attributed to the bandgap shrinkage. The dependence of the change of absorption coefficient on photon energy, temperature and excited carrier densities is discussed. !10