InterlayerΓ-Xscattering in staggered-alignmentAl0.34Ga0.66As-AlAs ternary alloy multiple-quantum-well structures

Abstract
The interlayer Γ-X scattering rate of photoexcited electrons was measured in staggered-alignment Al0.34Ga0.66As-AlAs ternary alloy multiple-quantum-well structures. The scattering process was directly probed by femtosecond pump-and-probe spectroscopy. The mean Γ-X scattering time of electrons across the interface between Al0.34Ga0.66As layers and AlAs layers at 4.2 K is determined to be 1.2 ps, which is longer than that observed recently in GaAs-AlAs short-period superlattices and is 20 times longer than that observed in bulk GaAs at 295 K. The slowing mechanism is ascribed to the small penetration of the evanescent Γ electrons into the AlAs barrier layers