Metallization of the {\beta}-SiC(100) 3\times2 Surface: a DFT Investigation

TL;DR

This DFT study investigates how hydrogenation affects the electronic and vibrational properties of the {eta}-SiC(100) 3x2 surface, revealing conditions for metallization and associated vibrational modes.

Contribution

It provides new insights into hydrogen-induced metallization of {eta}-SiC surfaces and identifies vibrational signatures and diffusion barriers relevant to surface modifications.

Findings

Metallization occurs when hydrogen occupies second silicon layer sites.

A new vibrational mode at 1870 cm-1 is associated with second-layer hydrogen.

Hydrogen diffusion barrier from second to third silicon layer is 258 meV.

Abstract

Using density functional theory (DFT) we report results for the electronic structure and vibrational dynamics of hydrogenated {\beta} reconstructed Silicon Carbide (001) (3x2) surfaces with various levels of hydrogenation. These results were obtained using density functional theory with a generalized gradient exchange correlation function. The calculations reveal that metallization can be achieved via hydrogen atoms occupying the second silicon layer. Further increases of hydrogen occupation on the second silicon layer sites result in a loss of this metallization. For the former scenario, where metallization occurs, we found a new vibrational mode at 1870 cm-1, which is distinct from the mode associated with hydrogen atoms on the first layer. Furthermore, we found the diffusion barrier for a hydrogen atom to move from the second to the third silicon layer to be 258 meV.