Optical and structural properties of hydrogenated silicon films prepared by rf-magnetron sputtering at low growth temperatures: Study as function of argon gas dilution

Two series of hydrogenated silicon thin films were deposited by the rf-magnetron sputtering (RFMS) at relatively low growth temperatures (Ts = 100 °C), in order to use the new generation of substrates sensitive to elevated temperatures. The effect of the argon gas diluted in hydrogen, on the optical and on the structural properties was carefully investigated by means of optical transmission (OT) measurements, Fourier transform infrared spectroscopy and spectroscopic ellipsometry (SE) technique. The results of this investigation suggest the existence of a threshold dilution around a gas mixture of argon (40%) and hydrogen (60%) for which the crystallization occurs, even at low deposition temperatures. The difference between the amorphous and the crystallized structures is well revealed by the OT and the IR absorption results, and strongly confirmed by the SE ones. The production of Si crystallites in the plasma as means of producing nanocrystalline by RFMS is suggested.