First-principles local density cluster calculations show that a Schottky junction may be formed in a nanoscale Au–Si(111) systems. The calculated Schottky barrier height value depends on the nanosystem’s geometry and varies from 0.5 to 1.35 eV. The total energy calculations show that the metallic gold/silicon system is unstable if the thickness of the gold is more than 2–3 monolayers. ©1997 American Institute of Physics.