Thermal decomposition of alkoxy monolayers grafted on silicon: A mechanistic model

A recent spectroscopic study showed that alkoxy monolayers grafted on a (111) silicon surface thermally decompose in the 200-400 C range by fragmentation of the alkyl chains [Surf. Sci. 601 (2007) 3961]. Here this behavior is reproduced by a numerical simulation, assuming that the elementary fragmentation steps have different probabilities, depending on the length of the fragments formed. The variation of the CH₂/CH₃ ratio, as determined experimentally by infrared spectroscopy, is reproduced with a set of fragmentation probabilities consistent with the enthalpy variation associated with each corresponding step.