Thermal decomposition of alkyl monolayers covalently grafted on (111) silicon

Alkyl monolayers have been covalently grafted onto atomically flat (111) hydrogenated silicon surfaces through hydrosilylation of 1-alkenes. The thermal stability of the layers under oxidizing or reducing atmospheres has been investigated by quantitative in situ infrared spectroscopy, using a specially designed variable-temperature cell. The layers are thermally stable up to 250°C. In the range of 250-300 °C, the main reaction is alkene desorption accompanied with silicon oxidation. The characteristic desorption temperature is not significantly affected by changing the atmosphere, the initial packing density of the layers, or the chain length from C18 to C6, but very short chains appear more stable.