Origin of the metallic field effect

The electric field effect of epitaxial silver films on mica in vacuum is studied as a function of temperature, thickness, and surface specularity. Attempts to interpret the data in terms of field-induced changes in carrier density, in film thickness, or in surface scattering, each modified by a size effect, lead to the conclusion that the predominant mechanism for altering the thin-film conductance is the change in surface scattering due to surface charging of the interface. This result is independent of the details of the size-effect model used. It implies field-induced changes in surface specularity of order ${10}^{-5\mathrm{}}$ that decrease with temperature. It also suggests that conduction electrons in silver sense a normally highly positively charged silver-mica interface.