We have studied the effects of heat treatments on the chemical and electronic properties of GaAs(110) surfaces covered with V or Pd to thicknesses of about 3 Å. The annealing improves the surface stoichiometry and reduces excess Ga generated during the deposition. Particularly forp‐type surfaces and coverages<1 Å, the anneal reduces the position of the Fermi level by as much as 0.3 eV, which indicates that deposition and post‐treatment affect the nature and energetics of defect/impurity levels. This rules out the possibility that Schottky barrier heights are universally determined by a single‐intrinsic defect. Exchanged Ga does not appear to influence the position of the Fermi level for interfaces with reactive metals. Ga itself, deposited separately on clean GaAs(110) surfaces, appears to form a fixed donor level ∼250 meV above the valence band maximum (VBM) over a broad coverage range. Beyond a coverage of ∼5 Å the Fermi levels onn‐ andp‐type GaAs essentially merge to a value of 0.63 eV above the VBM, indicating that this metal forms a conventional Schottky barrier.