Femtosecond relaxation dynamics of hot carriers in photoexcited In 0.53Ga 0.47As

Abstract

We report on ultrafast intervalley scattering of electrons measured in In 0.53Ga 0.47As by using femtosecond pump–probe spectroscopy. The spectral broadening of the exciton absorption band observed in the short time region is attributed to scattering of excitons created around the Γ point by the probe pulse with free carriers generated by the pump pulse. When electrons are excited so that the photoexcited electrons are not energetically allowed to transfer to the L valley, the rise time is as short as 0.5–1.0 ps, while it becomes slower (∼2.5 ps) when the intervalley transitions are allowed. These results yield a transfer time of ∼2 ps from the L to the Γ valley, which is comparable to that for GaAs.