SUBBAND EFFECTS ON HIGH-FIELD ELECTRON-TRANSPORT IN QUASI-ONE-DIMENSIONAL SYSTEMS

A detailed calculation of electron transport in AlxGa1-xAs/GaAs quantum wires by the use of a balance-equation approach, considering all possible acoustic and optical phonon scattering and taking fifteen subbands into account, is reported. Crossover from one dimension (1D) to three dimensions (3D) in both low- and high-field regimes is studied by investigating mobility and electron temperature as functions of the radius of quantum wire. At low temperatures, the linear mobility of a quasi-1D electron system may be ten times higher or ten times lower than that of a 3D system depending on the relative position of the Fermi energy to subbands. At very high electric field, the difference in the transport behavior of quantum wires with differing radii and that of a 3D system disappears as a result of high electron temperature and drift velocity.