Core-level study of the [formula omitted] system: beyond the room temperature saturation coverage

Abstract

Different coverages of K on the cold Si(100)c(4 × 2) surface were studied by core-level photoelectron spectroscopy. Both Si 2p and K 3p core-level spectra were recorded for different K coverages at ∼120 K. The evolution of the K 3p emission from the SiK interface and from the bulk and surface of K growing on the substrate is followed as a function of coverage. For coverages beyond the room temperature (RT) saturation amount ( θ s), the Si 2p spectra have essentially the same line shape as the spectrum from the surface with 1 θ s of K except for a broadening and an attenuation of the intensity. Two-domain 2 × 1 low energy electron diffraction (LEED) patterns were observed also from surfaces with coverages beyond the room temperature saturation amount. From a systematic analysis of the Si 2p and the K 3p photoemission together with the observations of the 2 × 1 LEED patterns, we conclude that the multi-layer growth does not occur in a simple layer-by-layer fashion on the cold Si(100) substrate. The presence of the interface core-level signals even after 16 times θ s points to a substantial island growth.