Modeling the effects of Si-X (X = F, Cl) bonds on the chemical and electronic properties of Si-surface terminated porous 3C-SiC

Porous silicon carbide offers a great potential as a sensor material for applications in medicine and energetics; however, the theoretical chemical characterization of its surface is almost nonexistent, and a correct understanding of its chemical properties could lead to the development of better applications of this nanostructure. Hence, a study of the effects of different passivation agents on the structure and electronic properties of porous silicon carbide by means of density functional theory and the supercell technique was developed. The porous structures were modeled by removing columns of atoms of an otherwise perfect SiC crystal in the [001] direction, so that the porous structure exhibits a surface exclusively composed of Si atoms (Si-rich) using different surface passivation agents, such as hydrogen (H), fluoride (F) and chloride (Cl). The results demonstrate that all of the passivation schemes exhibit an irregular band gap energy evolution due to a hybridization change of the surface. The structural analysis shows a great dependence of the bond characteristics on the electronegativity of the bonded atoms, and all of the structural and electronic changes could be explained due to steric effects. These results could be important in the characterization of pSiC because they provide insight into the most stable surface configurations and their electronic structures.