Size effects in multisubband quantum wire structures

We present a Monte Carlo simulation of multisubband quasi-one-dimensional GaAs-${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As structures. The simulation includes polar-optical-phonon and inelastic acoustic-phonon scattering and investigates the effect of changing confinement on electron velocity. Even at low longitudinal fields, for confinements in the range 50–230 Å, intersubband scattering has a profound effect on transport parameters. Under optimum conditions, differential mobility in excess of twice the bulk value at 300 K is obtained. Asymmetric geometry and high degree of confinement result in interesting differences from magnetotransport. In addition, resonance analogous to the magnetophonon effect occurs when the separation between lowest subbands is equal to the polar-optical-phonon energy.