ELECTRON-IMPURITY SCATTERING IN FREESTANDING QUANTUM WIRES - EFFECT OF DIELECTRIC CONFINEMENT

We calculate the impurity-scattering limited mobility of the one-dimen sional electron gas in a rectangular GaAs quantum wire confined in the vertical (growth) direction by n-modulation doped AlGaAs layers and f ree-standing along the transverse direction. The Fourier-transformed s cattering potential of the ionized impurity is obtained analytically b y solving the Poisson equation with z-dependent electrostatic permitti vity. An abrupt permittivity change at the GaAs(AlGaAs)/air interfaces gives rise to the image charge effect which strongly modifies the unp erturbed scattering potential. We show that the ''image impurity'' sca ttering tends to drastically reduce the electron mobility for sufficie ntly small (similar to 10 nm) transverse wire widths. (C) 1997 America n Institute of Physics.