Laser-induced alloy nanoparticles on Au-Sn thin layers

Abstract

The paper analyses the process of Au-Sn alloy nanoparticles (ANPs) formation by laser-induced dewetting of thin intermetallic layers for the first time. Tests were carried out for several samples with different Au-Sn atomic ratios and different total layer thicknesses (7.5 and 15 nm). The initial parameters of the samples were verified by spectroscopic ellipsometry (SE). To develop the experiment, a nanosecond ytterbium fiber laser (Yb:glass) with a wavelength of 1064 nm was used. The study was carried out both with the use of single laser pulses as well as raster scanning of the given surface. The use of two modes allowed to determine the impact of key process parameters (including pulse energy, degree of pulse overlap and laser fluency) on the formation, evolution, morphology, distribution and chemical composition of the obtained structures. The optimal conditions for the formation of Au-Sn ANPs were established.The samples were analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The chemical composition was analysed by means of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The optical properties of the obtained ANPs were determined by spectroscopic ellipsometry and the morphology and chemical composition were examined by transmission electron microscopy (TEM).