ROLE OF SILYLENE IN THE DEPOSITION OF HYDROGENATED AMORPHOUS-SILICON

The role of silylene in the laser deposition of hydrogenated amorphous silicon has been studied with laser-induced fluorescence and deposition rate measurements. The rate constants of the reactions of silylene with silane and disilane and of the reverse reactions have been determined. The results show that silylene is rapidly consumed, exhibiting only a small effective lifetime. It proves that generally silylene will hardly be able to reach the surface to form amorphous silicon. The comparison of the kinetic data with the deposition rates shows that in IR laser CVD silylene starts the gas-phase chemistry and that disilene is the main film-forming molecule. The UV laser process starts with a different primary dissociation leading to silylsilylene, which also rearranges to the film-forming disilene.