Frequency Dependence of the Electron Conductivity in the Silicon Inversion Layer in the Metallic and Localized Regimes

The conductivity of electrons in the inversion layer of silicon has been measured from 0 to 40 cm^-1 at 1.2^∘{}K in the metallic and localized regimes. The correlation between σ(T) and σ(ω) in the localized regime suggests that the drop in conductivity at low electron concentrations is caused by the appearance of a gap at the Fermi level.