The GaSe half-sheet termination layer provides an epitaxial and chemical stable electronic passivation of the Si(1 1 1) surface. Gold was deposited on n(+)- and p-doped Si(1 1 1):GaSe half-sheet terminated surfaces and the evolution of the Si(1 1 1):GaSe/Au interface and the Schottky barrier formation have been investigated. The GaSe half-sheet van der Waals surface termination on the Si(1 1 1) substrate do not modify the Si/Au Schottky barrier height but almost completely suppresses the Si/Au interface reaction at gold coverages <5 mL. The substrate chemical and electronic properties were investigated in-situ by high-resolution synchrotron excited X-ray photoelectron spectroscopy (SXPS). (C) 2004 Elsevier B.V. All rights reserved.