Strongly enhanced effective mass in dilute two-dimensional electron systems: System-independent origin

We measure the effective mass in a dilute two-dimensional electron system in (111)-silicon by analyzing temperature dependence of the Shubnikov-de Haas oscillations in the low-temperature limit. A strong enhancement of the effective mass with decreasing electron density is observed. The mass renormalization as a function of the interaction parameter r_s is in good agreement with that reported for (100)-silicon, which shows that the relative mass enhancement is system- and disorder-independent being determined by electron-electron interactions only.Comment: As publishe

Conductivity corrections in a strongly correlated and disordered two-dimensional electron system

We have measured the resistivity rho of a dilute two- dimensional electron gas near the (111) silicon surface as a function of a temperature. Since the valley degeneracy in such structures g(v) is 6, the dimensionless radius r(s) approaches 50 at electron densities significantly larger than in previously studied (100)Si or p-AlGaAs/GaAs systems. We have observed a nonmonotonical behavior of rho(T), the resistivity slowly decreasing with the temperature decreasing for temperatures above Tapproximate to1 K and increasing at lower temperatures for electron densities corresponding to rhosimilar toh/e(2), when the metal-insulator transition is expected. Such nonmonotonic behavior can be tentatively described by corrections to the conductivity due to electron-electron interaction with negative Fermi-liquid constant F(0)(sigma)approximate to-0.25

Coulomb blockade in triangular lateral small-size quantum dots

An AlGaAs/GaAs lateral quantum dot of triangular shape with a characteristic size L studied. Single-electron oscillations of the conductance G of this dot were measured at G G approximate to 0.5e(2)/h, a decrease was found not only in the amplitude but also in the period of the oscillations. A calculation of the 3D-electrostatics demonstrated that this effect is due to a change in the dot size produced by control voltages. (C) 2003 Elsevier B.V. All rights reserved

Coulomb blockade in a lateral triangular small quantum dot

An AlGaAs/GaAs lateral quantum dot of triangular shape with a characteristic size L this type) containing less than ten electrons was studied theoretically and experimentally. Single-electron oscillations of the conductance G of this dot were measured at G When going from G found not only in the amplitude but also in the period of oscillations. A calculation of the electrostatics demonstrated that this effect is due to a change in the dot size produced by control voltages. (C) 2002 MAIK "Nauka/Interperiodica"

Transport of a two-dimensional electron gas in a lattice of diffusive and thermalizing scatterers

Classical and quantum transport in a new kind of two- dimensional (2D) systems with artificial scatterers-2D electron gas in an array of diffusive and thermalizing scatterers (AuGeNi alloy dots)- was studied experimentally, It is shown that this array leads to a strong diffusive and inelastic scattering of the 2D electrons. As a result, several features in transport properties were observed: commensurability magnetoresistance peak. anomalies of the Hall resistance. unusual behavior (linear temperature dependence, saturation of the negative magnetoresistance) of the quantum interference corrections to the conductivity, which is due to the nontrivial dephasing in the system. (C) 2002 Elsevier Science B.V. All rights reserved