ENHANCEMENT OF THE ELECTRONIC EFFECTIVE-MASS IN QUANTUM WIRES

We show that the nonparabolicity and spin splitting enhance electron e ffective mass appreciably in a quantum wire. In bulk materials, these effects are usually small since electrons are near the conduction-band edges. In quantum wires, strong confinement puts the electrons far fr om the conduction-band edge, giving rise to large nonparabolicity effe cts. We derive a simple expression for the effective mass parallel to the transport direction in the quantum wire, taking into account the b and nonparabolicity, anisotropy, and spin splitting. We apply our form alism to GaAs/Al0.3Ga0.7As quantum wires and find that the parallel ma ss could be 50% more than the bulk value for a wire width of 50 angstr om.