Controlling thermal transport and dewetting in nanoscale molten metal films

Pulsed-Laser induced Dewetting (PLiD) is a simple technique that may be used to create metallic nanoparticles. A nanoscale metal film is plated on a Si or SiO2 substrate, and a pulsed laser is applied to melt the film, which then dewets and breaks up into nanoscale metal droplets. On removal of the laser pulse, the droplets resolidify as metallic nanoparticles. We model a setup in which the metal film is "patterned" onto the substrate, leaving certain areas free of metal. Though the substrate is optically transparent and does not absorb laser heat, it can absorb heat from the overlying metal, which is then transmitted laterally. Such lateral heat transport in the substrate can influence how melting and dewetting occurs in the overlying metal film, and ultimately how and where nanoparticle formation occurs. We present an asymptotically simplified model for the heat transport and fluid dynamics of the system, and proof-of-principle numerical simulations (implemented on a GPU) demonstrating how simple metal patterns may be used to control the final nanoparticle formation.