Hot-electron relaxation via optical phonon emissions inGaAs/AlxGa1-xAs quantumwell structures: dependence upon the alloy composition and barrierwidth

Abstract

We present a systematic investigation of thedependence of the hot-electron-optical-phonon interactions onAl composition and barrier width in GaAs/AlxGa1-xAsMQW structures. Raman scattering measurementsat 15 K are presented for samples with different barrier widthsand Al composition. The optical phonon energies emitted by thephotoexcited electrons in quantum wells were also determined byusing hot-electron-neutral acceptor luminescence techniques. Itis shown that the relaxation of hot electrons in the quantumwells is dominated by the GaAs LO phonon emission for smallx, but by AlAs-like LO phonons for larger Al composition. Forsamples with larger barriers, the electrons in the GaAs layerrelax mostly through the AlAs-like optical phonon emission.However, in samples with smaller barriers, the relaxation ofhot electrons is dominated by the GaAs optical phononemission.