MORPHOLOGY OF AMORPHOUS LAYERS BALLISTICALLY DEPOSITED ON A PLANAR SUBSTRATE

We report numerical simulation of the deposition of spherical particle s on a planar surface, by ballistic, straight-line trajectory transpor t, and assuming irreversible adhesion on contact with the surface or p reviously deposited particles. Our data indicate that the deposit form ed has a loosely layered structure within a few diameters from the sur face. This structure can be explained by a model of growth via chain f ormation. Away from the surface we found evidence of a monotonic, powe r-law approach to the bulk density. Both density and contact-statistic s results suggest that the deposit formed is sparse: the space-filling fraction is about 15%, and the average number of contacts is 2. The m orphology of the deposit both near the surface and in the bulk seems t o be a result of competition of screening and branching; nearly half o f all the spheres are either single-contact dangling ends, or branchin g nodes with more than two contacts.