DFT study of the dissociative adsorption of H2S molecule on the Si(1 1 1)-7 × 7 surface

Density functional theory calculation has been used to investigate the dissociative adsorption of hydrogen sulfide molecules on the Si(1 1 1)-7 × 7 surface. The reaction pathways for four hydrogen sulfide molecules dissociation over the adatom and rest atom sites are explored theoretically. The calculated results demonstrate that the initial dissociation of the first H2S molecule on both different sites to form the adsorbed SH species is no energy barrier. The elevated temperature can result in further SH bond dissociation, which is started by an SH insertion, and then followed by an H-transfer process. Subsequently, the second H2S attacks the adatom site (Sia), H atoms from the SH of the second H2S and surface SiaH are extracted to release the gas phase H2, and then the SH species from the second H2S occupies on the Sia site. Furthermore, the SH species inserts into SiSi backbond of the adatom, followed by an H-transfer process. In the same way, the SH species from the third and the fourth H2S molecule are also inserted into remnant SiSi backbonds of the adatom followed by an H-transfer process up to the formation of Si4+ state.