Subplantation model for film growth from hyperthermal species

A model describing film growth from hyperthermal (1--10^3 eV) species impinging on substrates is presented. The model involves a shallow subsurface implantation process called ``subplantation, '' energy loss, preferential displacement of atoms with low displacement energy E₃, leaving the high-E₃ atoms intact, sputtering of substrate material, and inclusion of a new phase due to incorporation of a high density of interstitials in a host matrix. Epitaxial or preferred orientation may result from the angular dependence of the E₃ and the boundary conditions imposed by the host matrix, i. e. , the ``mold'' effect. The discussion focuses on deposition of carbon diamondlike films, but examples of other systems, such as Si, Ge, and Ag, are provided as well. The model is supported by classical-ion-trajectory calculations and experimental data. The calculations probe the role of ion range, local concentration, backscattering coefficient, sputtering yield, and ion-induced damage in film evolution. The experimental data emphasize in situ surface-analysis studies of film evolution. The physical parameters of the deposition process that are treated are as follows: (i) nature of bombarding species (C^+ versus C^-, C^- versus C₂^-, C₍H₌^+, Ar^+, and H^+), (ii) ion energy, (iii) type of substrate, and (iv) substrate temperature during deposition.