Ab Initio Study of Octane Moiety Adsorption on H- and Cl-Functionalized Silicon Nanowires

Using first-principles calculations based on density functional theory, we investigated the effects of surface functionalization on the energetic and electronic properties of hydrogenated and chlorinated silicon nanowires oriented along the direction. We show that the band structure is strongly influenced by the diameter of the nanowire, while substantial variations in the formation energy are observed by changing the passivation species. We modeled an octane moiety absorption on the (111) and (110) surface of the silicon nanowire to address the effects on the electronic structure of the chlorinated and hydrogenated systems. We found that the moiety does not substantially affect the electronic properties of the investigated systems. Indeed, the states localized on the molecules are embedded into the valence and conduction bands, with no generation of intragap energy levels and moderated change in the band gap. Therefore, Si-C bonds can enhance protection of the hydrogenated and chlorinated nanowire surfaces against oxidation without substantial modification of the electronic properties. However, we calculated a significant charge transfer from the silicon nanowires to the octane moiety.

Automated summary

Using density functional theory calculations, the effects of surface functionalization on the energy and electronic properties of hydrogenated and chlorinated silicon nanowires were investigated. The band structure was found to be strongly influenced by the nanowire diameter, while the passivation species led to substantial changes in the formation energy. Absorption of an octane moiety on the silicon nanowire surfaces did not substantially affect the electronic properties, with no generation of energy levels within the band gap and a moderate change in the band gap. However, a significant charge transfer from the silicon nanowires to the octane moiety was calculated.