Time-resolved IR-absorption spectroscopy of hot-electron dynamics in satellite and upper conduction bands in GaP

The relaxation dynamics of hot electrons in the ${\mathit{X}}_6$ and ${\mathit{X}}_7$ satellite and upper conduction bands in GaP was directly measured by femtosecond UV-pump–IR-probe absorption spectroscopy. From a fit to the induced IR-absorption spectra the dominant scattering mechanism giving rise to the absorption at early delay times was determined to be intervalley scattering of electrons out of the ${\mathit{X}}_7$ upper conduction-band valley. For long delay times the dominant scattering mechanism is electron-hole scattering. Electron transport dynamics of the upper conduction band of GaP has been time resolved.