Gold and silver Schottky barriers on ZnS(110)

The evolution of the Schottky barrier between Au and Ag metal films and ZnS(110) has been studied using photoemission. Clean and well-ordered ZnS(110) surfaces were prepared by molecular beam epitaxy on cleaved GaP(110) surfaces. Chemical reaction and/or intermixing between the metal and substrate were not observed upon room temperature deposition. Substrate Zn 3d attenuation plots indicate that an initial layer-by-layer growth is followed by island growth at higher depositions. The Schottky barrier heights were found to be ΦAuB=2.19 and ΦAuB=1.81 eV, indicating a considerable dependence on metal work function. This observation agrees well with predictions of Schottky barrier heights based on the concept of metal-induced gap states and the influence of charge transfer based on electronegativities, and discussed in the light of current concepts of Schottky barrier characteristics