Control of the nucleation behavior during atomic layer deposition (ALD) of metals is of great importance for the deposition of metallic thin films and nanoparticles, and for nanopatterning applications. In this work it is established for Pt ALD, that the exposure to O2 during the O2 pulse of the ALD process is the key parameter controlling the nucleation behavior. The O2 dependence of the Pt nucleation is explained by the enhanced diffusion of Pt species in the presence of oxygen, and the resulting faster aggregation of Pt atoms in metal clusters that catalyze the surface reactions of ALD growth. Moreover, it is demonstrated that the O2 exposure can be used as the parameter to tune the nucleation to enable (i) deposition of ultrathin films with minimal nucleation delay, (ii) preparation of single element or core/shell nanoparticles, and (iii) nanopatterning of metallic structures based on area-selective deposition.
Mackus, A. J. M., Verheijen, M. A., Leick, N., Bol, A. A., & Kessels, W. M. M. (2013). Influence of oxygen exposure on the nucleation of platinum atomic layer deposition : consequences for film growth, nanopatterning, and nanoparticle synthesis. Chemistry of Materials, 25, 1905-1911. https://doi.org/10.1021/cm400562u