Atomic nature of the Schottky barrier height formation of the Ag/GaAs(001)-2 × 4 interface: An in-situ synchrotron radiation photoemission study

Abstract The Interface of Ag with p -type α2 GaAs(001)-2 × 4 has been studied to further understand the formation mechanism of the Schottky barrier height (SBH). In the initial phase of Ag deposition, high-resolution core-level data show that Ag adatoms effectively passivate the surface As-As dimers without breaking them apart. The Ag(+)-As(−) dipoles are thus generated with a maximal potential energy of 0.26 eV; a SBH of 0.38 eV was measured. Greater Ag coverage causes elemental segregation of As/Ga atoms, reversing the direction of the net dipole. The band bending effect near the interface shows a downward shift of 0.08 eV, and the final SBH is similar to the value as measured at the initial Ag deposition. Both parameters are secured at 0.25 A of Ag thickness prior to the observation of metallic behavior of Ag. Inadequacy of the metal-induced gap-state model for explaining SBH is evident.