An extension to the kinetic Monte Carlo simulation technique was developed in order to study thin film deposition and growth of a system approximating polycrystalline silicon. This method was developed to determine the effect of varying the angle of incidence of an atomic beam on the morphology of a poly-Si thin film grown on a crystalline Si substrate. This deposition procedure produced material comprised of individual grains, all with identical orientation; a first step towards modelling poly-Si. The addition of such grains does not significantly affect the bulk film properties relative to the single crystal case. The number of initial grains chosen to represent a set of pre-existing grains on the surface does not affect the gross morphology of the grown film once around 40 monolayers have been deposited. The chief advantage of this polycrystalline-like system is that it allows the observation of both columnar growth (at angles below about 65 •) and dendritic growth at angles above this value; growth of single crystalline material only shows the latter. This fact allows a comparison of results from atomic-scale simulation to existing theories that relate the angle of the morphological features of the grown film to the angle of the incident beam. We show that the simulation data are not particularly well represented by commonly used theories such as the tangent rule, or that due to Tait et al (1993 Thin Solid Films 226 196). Increased angles of incidence cause faster extinction of grains until a steady-state value of the number of grains is reached. When grains are nucleated on a heterogeneous substrate, here chosen as a crude description of Si on glass, increased substrate temperature results in larger grains, and higher angles of incidence result in fewer nucleated grains due to non-local shadowing.

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Epitaxial silicon thin films were deposited on Si(100) substrates at variable angles of incidence using well-collimated supersonic molecular beams of disilane, Si2H6. The resulting thin-film surface topology has been examined using atomic force microscopy. Rough surface morphology is observed as the beam angle of incidence is increased above ∼60°. Thin films deposited at substrate temperatures ⩽600 °C exhibit anisotropic features, which are elongated in a direction perpendicular to the incident beam. Increasing the substrate temperature leads to films with increased root-mean-square roughness and larger characteristic features, maintaining a nearly constant feature aspect ratio. Analysis indicates that the film feature size is controlled by a competition between roughening driven by the shadow instability and smoothening driven by surface mass transport.

Rare Event Dynamics Monte Carlo simulations have been used to investigate the possibility of growing porous crystalline material possessing vertical columnar morphology. This is achieved using a deposition process in which the incoming beam of atoms is held at a grazing angle and, importantly, is rotated azimuthally. For incident beams 80" from normal incidence, rotational speeds of around 1 revolution per second to 1 per 10 seconds were found to produce columnar thin film growth with essentially vertical walls. Slower rotational speeds, around 1 revolution per 30 seconds, produced a helical, but still vertical, columnar structure. Such so-called chiral structures are postulated to be potentially important optical materials. The effect of raising the temperature of the substrate is to decrease the density of the columns, but to broaden their size. This suggests that a temperature-rotational speed set of parameters could be found to produce designer pore sizes with relatively little variation in inter-column spacing and height and either with or without helical structure. Data for one such representation are presented. A movie of the evolution of the nanostructural features of a vertical columnar material is included.