A general expression based on the interfacial layer model is derived for the equilibrium Schottky barrer height, and it is applied to annealed Au‐GaAs contacts. Relations between the experimental barrier height, relative interfacial layer thickness and interface charge values, and the interface state energy distribution spectra are presented. The validity of the interfacial layer model is demonstrated. The obtained barrier height values and the near‐ohmic behavior after high‐temperature annealing are probably due to ionized donor type interface states in the upper half of the forbidden gap.