Quenched Disorder Effects in Electron Transport in Si Inversion Layers in the Dilute Regime

In order to reveal the effects of disorder in the vicinity of the apparent metal-insulator transition in 2D, we studied the electron transport in the same Si- device after cooling it down to 4 K at different fixed values of the gate voltage $V^\mathrm{cool}$. Different $V^\mathrm{cool}$ did not modify significantly either the momentum relaxation rate or the strength of electron-electron interactions. However, the temperature dependences of the resistance and the magnetoresistance in parallel magnetic fields, in the vicinity of the 2D metal-insulator transition, carry a strong imprint of the quenched disorder determined by $V^\mathrm{cool}$. This demonstrates that the observed transition between metallic and insulating regimes, besides universal effects of electron-electron interaction, depends on a sample-specific localized states (disorder). We report an evidence for a weak exchange in electrons between the reservoirs of extended and resonant localized states which occur at low densities. The strong cool-down dependent variations of $\rho(T)$, we believe, are evidence for developing spatially inhomogeneous state in the critical regime.