Film deposition on particles trapped in the sheath of reactive dusty plasma: effect of size distribution

We report our results on a radio-frequency plasma reactor used for thin-film deposition on particles. Deposition experiments in a reactive dusty plasma seeded with a bimodal distribution of seeds reveal that the mean film thickness is proportional to the deposition time. However, the deposition rate is not uniform for all particles. The distribution of deposition rates is obtained from measurements of the size distribution of the deposited films. The results show that the deposition rate exhibits a wide, approximately exponential distribution, which is attributed to spatial nonuniformities and gradients in the space between the electrodes. The conformity of the deposited films onto the surface of spherical seed particles is studied as a function of time. We find that the sphericity of the deposited film is generally good although deposition on the smallest seeds of this study (0.115 μm in radius) show a higher incidence of nonspherical coatings.