Fabrication of silver thin film for single-crystalline nanopillar: effects of thickness and grain size

A single-crystalline metallic nanostructure with a controlled crystallographic texture is expected to reduce optical losses. We have attempted to fabricate a single-crystalline metallic nanostructure using a physical technique only. The grain growth mechanism in silver films deposited on a highly transparent SiO2 substrate was elucidated by electron backscatter diffraction (EBSD) methods with nanoscale resolution. EBSD analysis suggested that the silver films deposited on SiO2 at lower thicknesses have a strong (111) texture. Additionally, we performed a grain size analysis using the EBSD crystal orientation map. When the film thickness increased from 154 to 1017 nm, most of the grains grew to a size of approximately 800 nm. Moreover, we successfully fabricated a conical nanopillar (undersurface diameter 450 nm) in a (111)-oriented large growing grain at the film thickness of 1017 nm by focused ion beam milling. A single-crystalline silver nanopillar was directly fabricated in controlled silver films using only physical processing.