Hydrogen related crystallization in intrinsic hydrogenated amorphous silicon films prepared by reactive radiofrequency magnetron sputtering at low temperature

We present an investigation on the transition from amorphous to nanocrystalline silicon and associated hydrogen changes during the first steps of hydrogenated nanocrystalline silicon growth for films elaborated by reactive radiofrequency magnetron sputtering at a substrate temperature as low as room temperature and for deposition times varying from 3 to 60 min. Complementary experimental techniques have been used to characterize the films in their as-deposited state. They are completed by thermal hydrogen effusion experiments conducted in the temperature range, from room temperature to 800 °C. The results show that, during the initial stages of growth, the presence of a hydrogen-rich layer is necessary to initiate the crystallization process.

► Nanocrystalline silicon growth at room temperature.
► Transition from amorphous to nanocrystalline silicon.
► Chemical reactions of H atoms with strained SiSi bonds.
► H selective etching and chemical transport caused the silicon nucleation.