Study of Pt growth on Si, Al2O3, Au, and Ni surfaces by plasma enhanced atomic layer deposition

Atomic layer deposition is a powerful technique for achieving atomic-level control in the deposition of thin films and nanoparticles. The ultrathin noble metal films can be applied in many functional devices, but it is a challenge to obtain such films since the island growth mode generally happens instead of the layer growth mode. In this work, the nucleation and growth of platinum on Si, Al2O3, Au, and Ni substrates were studied using (MeCp)PtMe3 and O-2 plasma as a precursor and a co-reactant, respectively. The evolution of Pt coverage on different surfaces was observed and discussed based on the experimental results by x-ray photoelectron spectra. The chemical adsorption of the precursor and the following processes like metal atom diffusion on substrate surfaces and up-stepping onto the existing metal islands were considered to dominate the growth before continuous films formed. The chemisorption determined the metal coverage on bare substrate surfaces, and the total coverage was influenced by metal atom diffusion and up-stepping behaviors that are determined by surface energy relationships between the deposited metal and substrate surfaces. Pt films were easier to form on Al2O3 and Ni surfaces compared with on Si and Au surfaces, respectively. A model was proposed to help to understand the mechanisms in the nucleation and growth processes, involving the chemisorption, diffusion, and up-stepping, which contributed to prepare ultrathin continuous Pt films on different substrates.

Automated summary

The study observed the evolution of Pt coverage on different surfaces based on experimental results, revealing the importance of chemisorption, metal atom diffusion, and up-stepping in film growth. Pt films were easier to form on Al2O3 and Ni surfaces compared with on Si and Au surfaces.