Hydrogen induced surface metallization of $\beta$-SiC(100)-($3\times 2$) revisited by DFT calculations

TL;DR

This study uses DFT calculations to explore hydrogen adsorption on SiC(100) surfaces, revealing alternative stable sites and offering new insights into the surface's metallic behavior.

Contribution

It presents a novel interpretation of hydrogen adsorption sites on SiC(100) surfaces, challenging previous assumptions about the origin of surface metallization.

Findings

Hydrogen adsorbs at unusual bridge sites above third-layer Si dimers.

Multiple-layer hydrogen adsorption is compatible with a different surface geometry.

The electronic structure of the metallic surface is reinterpreted based on new adsorption sites.

Abstract

Recent experiments on the silicon terminated $3\times 2$ SiC(100) surface indicated an unexpected metallic character upon hydrogen adsorption. This effect was attributed to the bonding of hydrogen to a row of Si atoms and to the stabilization of a neighboring dangling bond row. Here, on the basis of Density-Functional calculations, we show that multiple-layer adsorption of H at the reconstructed surface is compatible with a different geometry: besides saturating the topmost Si dangling bonds, H atoms are adsorbed at rather unusual sites, \textit{i.e.} stable bridge positions above third-layer Si dimers. The results thus suggest an alternative interpretation for the electronic structure of the metallic surface