Cs and O adsorption on Si(100) 2×1: A model system for promoted oxidation of semiconductors

Abstract

We present Auger-electron spectroscopy, low-energy electron diA'raction, and Ap measurements of Cs adsorption on Si(100) and subsequent oxidation of the substrate. Our data provide evidence against complete charge transfer from the alkali metal to Si as proposed recently. The amount of Si02 produced by alkali-metal-promoted low-temperature oxidation of silicon is found to be strictly proportional to the alkali-metal coverage, which, together with measured changes in the work function during oxidation, allows us to question some of the current mechanisms put forward to explain this phenomenom.

Electron work function decrease in SIMS analysis induced by neutral cesium deposition

“…The simulated concentrations obtained by TRIDYN gave only approximate values of the Cs surface concentration C Cs . Nevertheless they allow to compare the variations of the electron work function as a function of the Cs surface concentration to experimental results found in literature for the adsorption of Cs on different samples (without ion irradiation, and thus no perturbation of the sample surface) [10,11,13,35].…”

Impact of O2 exposure on surface crystallinity of clean and Ba terminated Ge(100) surfaces

“…Instead, oxidation tendency increases, and resistance against amorphization decreases with increasing Ba coverage in a monotonic manner. The oxidation promoting effect of Ba is in line with the oxidation promoting properties of other electropositive elements such as Cr, Na, and K [21,22]. We suspect that the larger electronegativity difference between Ba and Ge (Dx = 1.12) compared to between Sr and Si (Dx = 0.95) could be at the basis of the rather different impact on oxidation behaviour.…”

Progress into Understanding of Alkali Metal Interaction with a Silicon Surface

“…The decrease of the substrate work function with alkali metal coverages (-3, -3.2, -3.4 eV for Na, K and Cs respectively [10,[46][47][48][49]) also indicates that the covalent bonding between the alkali and the silicon atoms is polarized similar to the case mentioned above of Cs covered transition metal surfaces [15]. Also of interest, the absence of significant core level shift at the Si 2p core level mentioned above indicates that alkali metals (except lithium) do not interdiffuse through the surface with no silicide formation in contrast to the behavior observed for many other metals [5].…”