IMPURITY-SCATTERING LIMITED ELECTRON-MOBILITY IN FREE STANDING QUANTUM WIRES - IMAGE CHARGE EFFECT

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 scattering potential of tile ionized impurity is obtained by solving the Poisson equation w ith z-dependent electrostatic permittivity in order to take into accou nt the image charge effect due to the abrupt permittivity change at th e GaAs/air interfaces. We show that the ''image impurity'' scattering tends to drastically reduce the electron mobility for sufficiently sma ll (approximate to 10 nm) transverse wire widths.