Pulsed-Laser Induced Dewetting of Metallic Nanostructures

This dissertation explores the fluid dynamics of nano and microscale liquid metal filaments, with an emphasis on experimentally investigating the influences and causes of filament breakup and metallic nanostructure formation. Understanding and manipulating the liquid state properties of materials, especially metals, have the potential to advance the development of future technology, particularly nanoscale technology. The combination of top-down nanofabrication techniques with bottom-up, intrinsic self-assembly mechanisms are a powerful fusion, because it permits new and unusual nanostructures to be created, whilst revealing interesting nanoscale physics.

In fluid dynamics, wetting and dewetting is the spontaneous natural process that occurs when a liquid supported on a substrate seeks to minimize its systems energy. Either by covering the substrate surface, in the case of wetting, or by rupturing and assembling into a collection of smaller liquid fragments; typically droplets, with minimal contact and surface area with the substrate and the surrounding gaseous environment. Due to metal’s unique liquid state properties, like low viscosity and high surface energy, the dewetting phase is the prescient realm to experimentally access and study the governing dynamics, instabilities, and mass transport behind metallic nanostructure formation.

The work contained in this dissertation seeks to address some basic scientific questions, such as: How to develop reasonably simple but predictive models to describe the competition between instability mechanisms that result in filament coalescence or fragmentation, as a function of filament extent? How to manipulate the intrinsic material properties of liquid metals, like surface energy, to initiate instabilities, like those similar to the Rayleigh-Plateau instability, to encourage self-assembly at the nanoscale? A focused and collaborative approach is contained herein where experiments will be used to drive theoretical and computational simulations and vice versa.