Experimental characterization of quasi-2-dimension nanoporous gold ultra-thin film from nano to micro length scale

Abstract

Quasi-2D nanoporous gold ultra-thin films have been elaborated and investigated by specific surface approaches. Three different microscopy techniques (Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM)) have been used for the characterizations. A careful statistical analysis of experimental images has been done, thanks to the development of a dedicated image analysis software. It reveals that the inhomogeneous gold nanomesh at low length scale becomes homogeneous at a length scale larger than the biggest pores size of about 2 μm, with a constant opacity reaching 35%. At such a scale, the ligaments present an average diameter of 20 nm and an average length of 70 nm. While TEM and SEM present similar results, AFM overestimates the geometric characteristics due to tip convolution effect. However, the topology of the nanomesh is not affected. This study also reveals pores with a much larger size in the quasi 2D nanoporous ultra-thin film than in its bulk counterpart for similar ligaments diameters, which could play an important role in its mechanical properties.