On the coverage and structure of the [formula omitted]-R30 surface phase

Abstract

The study addresses the nature and coverage of the (√3×√3) surface phase of the Ag Si(1 1 1) interface that has remained unresolved in literature. Ag is adsorbed in ultra-high vacuum on to the (7 × 7) reconstructed Si(1 1 1) surface with a deposition rate of 3.3 × 10 12 atoms cm −2s −1. The initial stages of growth and intermediate equilibrium phase formation are determined by using Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES) and Electron Energy Loss Spectroscopy (EELS). For depositions carried out at higher temperatures (> RT), several plateaus in the Auger uptake curve at 0.33, 0.66 and 1.0 ML coverages of Ag with the (√3×√3)-R-30° LEED structures are formed. It is observed that a minimum coverage (θ) of 0.33 ML is required for the formation of the (√3×√3) phase. The (√3×√3) phase obtained at higher substrate temperatures causes the reappearance of the p-electron related states, that were quenched by 1.0 ML adsorption at RT. The EELS obtained at these (√3×√3) plateaus are observed to be different, indicating different local structural surface phases for the same long range order.