Nucleation-Controlled Growth of Nanoparticles by Atomic Layer Deposition

We demonstrate a method for growing metal nanoparticles (NPs) by atomic layer deposition (ALD) with the ability to vary aerial density and NP size using nucleation control. Self-assembled monolayers (SAMs) preadsorbed on the substrate serve as a template for subsequent growth of the NPs by ALD. Defects in the SAM resulting from incomplete formation time in solution are shown to act as nucleation sites for Pt. The strategy is demonstrated experimentally using ALD of Pt from a metal organic Pt precursor and O-2 counter reactant on silicon dioxide surfaces pretreated with octadecyltrichlorosilane SAMs. The aerial density and mean diameter of the Pt NPs are controlled by changing the SAM dip time and the number of ALD cycles. An isothermal nucleation model was developed in which several nucleation behaviors were considered in comparison with experimental data. A model incorporating nucleation incubation provided the best fit to the data.