STRONG LOCALIZATION OF ELECTRONS IN QUASI-ONE-DIMENSIONAL CONDUCTORS

We report on an experimental study of electron transport in submicrome ter-wide ''wires'' fabricated from Si delta-doped GaAs. These quasi-on e-dimensional (Q1D) conductors demonstrate the crossover from weak to strong localization with decreasing temperature. On the insulating sid e of the crossover, the resistance has been measured as a function of temperature, magnetic field, and applied voltage for different values of the electron concentration, which was varied by applying the gate v oltage. The activation temperature dependence of the resistance has be en observed with the activation energy close to the mean energy spacin g of electron states within the localization domain. The study of nonl inearity of the current-voltage characteristics provides information o n the distance between the critical hops I:hat govern the resistance o f QID conductors in the strong localization (SL) regime. We observe th e exponentially strong negative magnetoresistance; this orbital magnet oresistance is due to the universal magnetic-field dependence of the l ocalization length in QID conductors. The method of measuring the sing le-particle density of states (DOS) in the SL regime has been suggeste d. Our data indicate that there is a minimum of DOS at the Fermi level due to the long-range Coulomb interaction. [S0163-1829(98)03936-8].