Subpicosecond real-space charge transfer in type-II GaAs/AlAs superlattices

Abstract

We have directly measured the real-space transfer times associated with \ensuremath{\Gamma}\ensuremath{\rightarrow}X intervalley scattering in type-II GaAs/AlAs superlattices by femtosecond optical pump and probe spectroscopy. We domonstrate that the scattering rate for this unique process connecting electron states in different slabs of the superlattice is related to the spatial overlap of the electronic envelope wave functions in different satellite minima.