Nickel and Nickel-Based Nanoalloy Thin Films from Alcohol-Assisted Chemical Vapor Deposition

Abstract

The growth of nickel and nickel-based alloys was investigated using the pulsed-spray evaporation (PSE) CVD process in hydrogen-free atmosphere. This process relies on the reactivity of ethanol, which was investigated using mass spectrometry. In fact, the dehydrogenation of ethanol to form acetaldehyde is identified as the reaction pathway that provides hydrogen atoms necessary to desorb acetylacetonate ligand of the precursor. This global reaction leads to the formation of metallic nickel film either in the hexagonal (hcp) lattice at low temperature or in the cubic (fcc) one at temperatures higher than 240 °C. In conditions where the fcc−Ni phase is deposited, the PSE−CVD process enables the deposition of Ni−Cu alloy thin films with fully controlled composition, whereas Ni−Ag forms polycrystalline silver, in addition to an amorphous phase containing silver and nickel. The synthesis of Ni−Co alloy thin films was performed under conditions where the hcp−Ni phase was obtained, providing for the first time a route toward deposition of nickel-rich hcp−Ni−Co.