Effect of plasma treatment on nucleation of Au nanoparticles

Abstract

Nucleation is a basic issue in film science and technology, and it plays a vital role in the field of functional devices characterized in ultra-thin and continuous thin films. In this paper, Au clusters were deposited on three different substrates (BOPP, Si (100) and carton support film) by means of magnetron sputtering with or without air plasma pretreatment. The results show that plasma treatment conducted on BOPP substrate decreased the water contact angle significantly, indicating an enhanced surface energy of BOPP substrate. The introduction of polar groups (C–O/C–N, C=O/N–C=O and O–C=O) as well as a modified topology were responsible for the improvement of hydrophilicity. Au nanoparticles prepared on untreated substrates exhibited a non-uniform topology independent of substrate type. After plasma treatment, Au nucleation densities were increased greatly, and the nucleus sizes were much smaller. Based on the thermodynamics theory of heterogeneous nucleation, by means of plasma treatment, the substrate surface energy was enhanced and the film-substrate interfacial energy was decreased simultaneously, and both of them contributed to the higher nucleation density and smaller cluster size.