Nanosphere Lithography via Continuous Convective Assembly

Continuous Convective Assembly (CCA) was used to create monolayer arrays of hexagonal closed packed nanospheres using a stepper motor instrument. The convective assembly occurs at the meniscus of the nanosphere solution due to the water evaporation from the films surface resulting in the formation of a monolayer of nanospheres. The Atomic Force Microscopy (AFM) was used to determine the order of the nanospheres. Next, Nanosphere Lithography (NSL) was used to generate ordered arrays of triangles by using the monolayers of nanospheres as a mask for the evaporation of silver. AFM and Scanning Electron Microscope (SEM) were used to examine and characterize the order of the triangular shaped silver nanocluster arrays. A number of variables were considered in the experiment such as type of substrate, volume percent of solution, withdrawal rate, cleaning method, and size of nanospheres. The triangular arrays are used as substrates for surface-enhanced Raman spectroscopy (SERS). Nanosphere lithography could be used to prepare optical units, electronic Read Only Memory (ROM) devices and for the fabrication of periodic particle array (PPA) surfaces.