Nucleation and initial growth of platinum islands by plasma sputter deposition

Abstract

The nucleation and islands growth of platinum have been followed from an early stage through to complete substrate coverage. Thus, this study of initial stages of thin film growth has allowed to improve the understanding of growth mechanisms and to control the final nanomaterials structure. In the presented deposition method, the metal atom source is a negatively biased metal wire submitted to the bombardment of ions created in HF plasma. The originality of this plasma sputtering technique is that in addition to the metal atom flux, the substrate surface is submitted to a high flux of low energy ions, inducing a high atomic surface mobility and modifying the growth mode with respect to conventional deposition techniques (magnetron sputtering or evaporation). Platinum deposits have been investigated by ex situ characterisation techniques: grazing incidence-small angle X-ray scattering (GISAXS) and X-ray diffraction (GIXD) in conjunction with transmission electron microscopy (TEM). Using morphological parameters as coverage rate, islands number density and islands size, different mechanisms (scale laws, islands mobility, coalescence, etc.) governing the growth are described vs. Ar ion and Pt atom energies and fluxes.