Quantum Mechanical Investigation of the Influence of the Local Environment on the Vibrational Properties of Hydrogenated Si(111)

M. F. JUÁREZ; E. M. PATRITO; P. PAREDES OLIVERA

AMER CHEMICAL SOC

Lugar: Washington ; Año: 2009 vol. 113 p. 681 - 681

Periodic density functional calculations were performed to investigate the vibrational properties of hydrogenated and grafted Si(111) surfaces as a function of surface coverage and subsurface oxidation. Surfaces terminated with -CH3, -CCH, and -Cl groups were considered. Subsurface oxidation was taken into account by oxidizing one, two, and three silicon back bonds. The effect of anharmonicity was considered in the calculation of thestretching frequencies of the Si-H and C-H groups. The effect of the different adsorbates on the polarization of the electron density of the SiH group and on the electronic structure of the surface was investigated by means of electron density difference and density of states analyses. The Si-H stretching frequency increases with the surface coverage of -CCH and -Cl species, and it decreases with the increase in the surface coverage of -CH3. Positive (negative) frequency shifts correlate with the increase (decrease) of electron density along