Phonon confinement effect observed in longitudinal magnetophonon resonance in Al0.3Ga0.7As/GaAs superlattices with/without AlAs thin barriers

Abstract
Electron-optical phonon interaction is studied in longitudinal transport through a series of Al0.3Ga0.7As/GaAs superlattices by measuring longitudinal magnetophonon resonance (MPR). In addition to well resolved MPR peaks caused by GaAs phonons, peaks ascribable to AlAs interface phonons are observed when a thin AlAs barrier is inserted at each GaAs/Al0.3Ga0.7As heterointerface. A calculation based on the Huang-Zhu model describes the features of experimental spectra. When the well width is reduced in Al0.3Ga0.7As/GaAs superlattices with narrow quantum wells, the AlAs-like phonon mode also becomes important in miniband transport.