ELECTRON-ENERGY RELAXATION VIA LO-PHONON EMISSION IN FREESTANDING GAAS WAFERS

The electron LO-phonon scattering rate is obtained for a thin free-standing GaAs wafer. The carriers are assumed to occupy only the lowest subband. The choice of confining potential is shown to make a quantitative difference in the variation of the scattering rate with wafer thickness. Phonon confinement effects are demonstrated to manifest themselves for thicknesses less than around 500 AA. It is shown that purely longitudinal surface modes are not allowed in these free-standing structures. Surface electromagnetic waves (polaritons), which are normal modes of the system exist, though it is argued that their interaction with electrons ought to be weak.