Optical phonon emission in GaAs/AlAs and GaAs/Al0.7Ga0.3As multiple quantum well structures

We have performed Raman scattering measurements and hot electron-neutral acceptor (hot(e, Angstrom)) luminescence experiments on Be-doped GaAs/AlAs and GaAs/Al0.7Ga0.3As multiple quantum well structures, with fixed well width of 50 Angstrom and barrier thickness of 5, 25, 50,120 Angstrom, to determine the optical phonon energy emitted by the hot electrons excited in the quantum wells. It was shown that the relaxation of electrons in the GaAs layer is dominated by the AlAs-like optical phonon emission for samples with larger barriers, but by GaAs optical phonons for smaller barriers. (C) 2001 Elsevier Science B.V. All rights reserved.