Thermal Stability of Organic Monolayers Grafted to Si(111): Insights from ReaxFF Reactive Molecular Dynamics Simulations

SORIA, FEDERICO A.; ZHANG, WEIWEI; VAN DUIN, ADRI C. T.; PATRITO, EDUARDO M.

ACS APPLIED MATERIALS & INTERFACES

AMER CHEMICAL SOC

Año: 2017 vol. 9 p. 30969 - 30969

1944-8244

e used the ReaxFF reactive molecular dynamics simulations to investigate the chemical mechanisms and kinetics of thermal decomposition processes of silicon surfaces grafted with different organic molecules via Si-C bonds at atomistic level. In this work, we considered the Si(111) surface grafted with n-alkyl (ethyl, propyl, pentyl, and decyl) layers in 50% coverage and, Si-CH3, Si-CCCH3 and Si-CHCHCH3 layers in full coverage. Si radicals primarily formed by the homolytic cleavage of Si-C bonds play a key role in the dehydrogenation processes that lead to the decomposition of the monolayers. Contrary to commonly proposed mechanisms that only involve a single Si atom center, we found that the main decomposition pathways require two Si lattice atoms to proceed. The ability of surface silyl radicals to dehydrogenate the organic molecules depends on the flexibility of the carbon backbones of the organic molecules as well as on the C-H bond strength. The dehydrogenation of n-alkyl chains ma