| AVS 61st International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Thursday Sessions |
| Session NS-ThP |
| Session: | Nanoscience Division Poster Session |
| Presenter: | Ebenezer Owusu-Ansah, University of Calgary, Canada |
| Authors: | E. Owusu-Ansah, University of Calgary, Canada C. Horwood, University of Calgary, Canada H.A. El-Sayed, Technische Universität, Germany V. I. Birss, University of Calgary, Canada Y. Shi, University of Calgary, Canada |
| Correspondent: | Click to Email |
The unique properties of metal nanoparticle arrays (MNAs) depend on their sizes and geometries, and they differ considerably from the individual atoms and the bulk material.MNAs have been at the frontier in fabrication of materials with enhanced optical, magnetic, plasmonic, and mechanical properties, in biosensors as well as in catalysts with optimized selectivity. Lithographic techniques are the major conventional methods used to generate MNAs, however, the processes are sophisticated and time consuming. The formation of sub-50-nm nanoparticle sizes has become increasingly difficult using lithography. Recently, thermal dewetting has been successfully used to form nanoparticle arrays of Au on dimpled Ta (DT) substrate, however, the major setback associated with this method is the deformation of the substrate when applied to high-melting point metals such as Pt. Pulsed laser dewetting is able to generate well-defined MNAs with the unique advantage of very little or no thermal damage to the substrate. Within the short width of the laser pulse, typically in the range of 7–12 ns, the laser energy is instantaneously converted into heat to dewet only the thin metal film with minimal or no heat transfer to the underlying substrate. We report here the results from our study on the formation of Pt MNAs using laser dewetting of Pt thin films on DT substrate under high vacuum condition. The DT substrate was fabricated using electrochemical anodization in highly concentrated H2SO4/HF solution. It has been demonstrated that dewetting occurs only at and beyond the threshold fluence. Beyond this threshold a single laser pulse was enough to achieve complete dewetting. The effect of several key parameters, including laser fluence, irradiation time, and film thickness, on the nanoparticle sizes and distribution was studied. To better characterize the MNA features, the percentage of dimples occupied by Pt nanoparticles was determined. As high as 80% of dimpled Ta occupancy can be achieved using pulsed laser dewetting. This study shows that laser dewetting is a novel method capable of annealing thin films of high-melting point Pt metal to achieve well-defined MNAs with narrow particle size distribution without subsequent damage to the DT substrate.