The Partially Chlorinated/Hydrogenated Si(111) Surface as a Template for the Formation of Nanopatterns

E. M. PATRITO; F. A. SORIA; P. PAREDES OLIVERA

Boston, MA

Congreso; 2013 MRS Fall Meeting; 2013

Materials Research Society

The oxidation of the perfect H−Si(111) surface and surfaces containing silicon dangling bonds surrounded by SiH groups were investigated for H2O and O2 oxidizing agents to identify elementary reaction steps and their corresponding energy barriers, in an effort to unveil the mechanism of oxidation of the first silicon bilayer of H−Si(111) in air. Density functional theory was employed to calculate the energy profiles along the reaction coordinate (1). The oxidation of the perfect H−Si(111) towards H2O and O2 has high energy barriers which prevent the room temperature oxidation. However, the presence of silicon dangling bonds (surrounded by SiH groups) readily catalyzes the reaction with O2 yielding a silanone intermediate of the form (Si2O)SiO where one of the silicon back bonds is oxidized. In the next step, the oxygen atom of the silanone inserts into a Si−Si backbond. The surface silyl radical (SiO2)Si is thus regenerated and this moiety initiates a chain reaction by hydrogen atom abstraction from a neighboring SiH group yielding a new silyl group ready to be oxidized by O2.