Localization and screening anomalies in two-dimensional systems

The self-consistent current theory for two-dimensional electron dynamics in strongly disordered environments is extended by an approximative incorporation of Coulomb interaction effects. Quantitative details of the theory are worked out for a Si(100) metal-oxide-semiconductor device at zero temperature which is doped with Na ions. The results are compared with experiments on the nonlinear variation of the resistivity with impurity concentration, on the mobility suppression for low electron concentration, on the metal-insulator phase-transition diagram, on the nonmonotonic variation of the dynamical conductivity with electron concentration, and with the results of laser-light absorption. Predictions are made about impurity-induced plasmon shifts and dampings, and on a depletion-field-induced mobility suppression which may lead to a metal-insulator transition. A long-time anomaly for current relaxations is predicted to yield a singular non-Drudian current spectrum showing up as a conductivity peak at very low frequencies.