Cs adsorption on Si(001) surface: ab initio study

TL;DR

This study uses first-principles density functional theory calculations to analyze cesium adsorption on silicon surfaces, revealing coverage-dependent electronic properties and bonding characteristics.

Contribution

It provides detailed insights into the atomic structure, electronic behavior, and bonding nature of Cs on Si(001) at different coverages using ab initio methods.

Findings

0.5 ML coverage results in metallic surface

1 ML coverage leads to semiconducting surface

Adsorption involves polarized covalent bonding

Abstract

First-principles calculations using density functional theory based on norm-conserving pseudopotentials have been performed to investigate the Cs adsorption on the Si(001) surface for 0.5 and 1 ML coverages. We found that the saturation coverage corresponds to 1 ML adsorption with two Cs atoms occupying the double layer model sites. While the 0.5 ML covered surface is of metallic nature, we found that 1 ML of Cs adsorption corresponds to saturation coverage and leads to a semiconducting surface. The results for the electronic behavior and surface work function suggest that adsorption of Cs takes place via polarized covalent bonding.