Large conductance modulation of gold thin films by huge charge injection   via electrochemical gating
  By using an electrochemical gating technique with a new combination of polymer and electrolyte, we were able to inject surface charge densities n_2D as high as 3.5 \times 10^15 e/cm^2 in gold films and to observe large relative variations in the film resistance, DeltaR/R', up to 10% at low temperature. DeltaR/R' is a linear function of n_2D - as expected within a free-electron model - if the film is thick enough (> 25 nm), otherwise a tendency to saturation due to size effects is observed. The application of this technique to 2D materials will allow extending the field-effect experiments to a range of charge doping where giant conductance modulations and, in some cases, even the occurrence of superconductivity are expected. 
D. Daghero, F. Paolucci, A. Sola, M. Tortello, G.A. Ummarino, R.S.   Gonnelli, Jijeesh R. Nair and C. Gerbaldi
cond-mat.mes-hall cond-mat.supr-con