Energy-band renormalization and energy-relaxation dynamics of theX6andX7satellite valleys in GaAs

Using femtosecond UV-pump–IR-probe absorption spectroscopy, energy-band renormalization of the ${\mathit{X}}_6$ and ${\mathit{X}}_7$ satellite conduction-band valleys and energy relaxation of electrons in the ${\mathit{X}}_6$ and ${\mathit{X}}_7$ valleys by intervalley scattering, ${\mathit{X}}_6$⇆Γ and ${\mathit{X}}_7$⇆Γ, as a function of photoexcited electron density, were observed in GaAs. The measured energy renormalization and its density dependence are compared with theory. It is determined that ${\mathit{X}}_7$→Γ intervalley scattering is faster than ${\mathit{X}}_6$→Γ intervalley scattering.