Abstract
Laser-induced chemical vapour deposition of SiO 2 films in a parallel configuration is a powerful technique for the growth of coatings in some special applications where other conventional low-temperature techniques cannot be applied. A CO 2 laser is more attractive than other lasers for industrial applications since it is less expensive and already widely used in the industry. Growing SiO 2 films is carried out by irradiating a gas mixture composed by SiH 4, N 2O and Ar with a continuous wave CO 2 laser. Energy absorption by the mixture causes a temperature increase in the gas phase which leads to the deposition process. Here we present a study of two important geometrical factors in our experimental set-up: the total flow rate of the reactant gases, and the distance between the laser beam and the substrate surface. Variations in gas flow cause changes in the absorption coefficient of the gas mixture and thus in the gas temperature, which mainly affects the growth rate. The beam-substrate distance influences the gas temperature owing to heat exchange between the gas and the substrate and to the collision rate of the chemical species in their diffusion path towards the substrate surface. Therefore, both the growth rate and the film properties change with this parameter.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call