The location of very small particles in silane RF discharge

The size and location of silicon particles that grow in a pure silane, capa citively coupled RF discharge, are measured by laser light scattering. The discharge conditions were similar to those typically used to produce amorph ous silicon devices, except the temperatures is 300 K, At early discharge t ime, when the particles are small (D similar to 15 nm), they are located at the middle of the discharge. The larger ones that occur at later discharge times form a double layer nearer the electrodes. Surprisingly, the particl es are not concentrated at the region of brightest discharge-light, which r epresents the distribution of high-energy electrons. Yet as expected, the d istribution of film deposition on the electrodes fits radical diffusion wit h a source proportional to light intensity. It is also shown, by tilting th e substrate, that a small gradient in plasma potential can have a major eff ect on particle positions.