Spinodal Dewetting to Create Self-Assembled and Organized Nanoparticles: A High-Throughput Approach

Metal nanoparticles on structured supports are used in many technological applications such as biosensing, energy harvesting, and electronics.  In every case, the functions and properties of the metallic nanostructures depend on their composition and structure (i.e. size, shape, and spatial distribution).  Challenges to using metal nanoparticles in these applications are the difficulties of optimizing the structure-property functionality over a large structural domain.  In this work, a new method is described to create a morphological gradient of particles on a substrate in a repeatable and controlled manner over a relatively large spatial domain using Pd on silicon nitride.  The approach, suited for high-throughput fabrication and characterization, is based on inducing precursor thin films to dewet from a substrate through spinodal dewetting.  Spinodal dewetting allows the creation of particles that have well-defined structural properties by adjusting a few variables: initial film thickness, annealing temperature and annealing time.  The morphologies of the particles were characterized using scanning tunneling and atomic force microscopies, and hydrodynamic stability and integral geometry analyses to confirm the dewetting mechanism.  In addition, the hydrodynamic instability theory provides a connection to the thermophysical properties of the system.  The dewetting approach is general to any metal/support system and provides an alternative, inexpensive, and robust means to rapidly create metal nanostructures.  It shows promise for large scale production of the metal structures, as well as understanding basic material properties.