Hot electron transport in GaAs quantum wells: non-drifting hot phonons

Experimental data concerning high-field parallel transport in GaAs/GaAlAs quantum well structures are reported. The results strongly suggest that (i) in modulation doped GaAs quantum wells the non-equilibrium LO phonons (hot phonons) are non-drifting, and (ii) in samples with similar 2D electron densities hot phonon effects increase with reduced dimensionality, and hence with increasing 3D electron concentration. Both observations are in excellent agreement with a recent model of high-field transport involving hot phonons.