The crystallographic relationships, growth morphology, chemical activity, and electronic properties of Ag deposited at room temperature on GaAs(100) c(2×8) and (4×6) surfaces were investigated. Ag(110) growth was observed independent of growth rates. The growth is three- dimensional (nucleated) and the interfaces are abrupt. Stabilization of the Fermi level occurs beyond Ag coverages of 10 Å, is uncorrelated with the appearance of the metallic Ag phase at ∠0.5 Å and appears to be dependent on the formation of atomiclike interfacial states near the bottom of the bandgap. Schottky barrier heights of 0.83 and 0.97 eV were determined for Ag on the c(2×8) and (4×6) surfaces, respectively. The results are at variance with current Schottky barrier models.