An experimental and computational study of size-dependent contact-angle of dewetted metal nanodroplets below its melting temperature

作者：Azeredo Bruno P; Yeratapally Saikumar R; Kacher Josh; Ferreira Placid M; Sangid Michael D

来源：Applied Physics Letters, 2016, 109(21): 213101.

DOI：10.1063/1.4968005

Decorating 1D nanostructures (e.g., wires and tubes) with metal nanoparticles serves as a hierarchical approach to integrate the functionalities of metal oxides, semiconductors, and metals. This paper examines a simple and low-temperature approach to self-assembling gold nanoparticles (Au-np)-a common catalytic material-onto silicon nanowires (SiNWs). A conformal ultra-thin film (i.e., <15nm thick) is deposited onto SiNWs and thermally dewetted, forming nanoparticles in the 6-70 nm range. Two parameters of its morphology are dependent upon dewetting conditions: particle size and particle contact angle. Using transmission electron microscopy imaging, it is found that annealing temperature profile has a strong effect on the particle size. Additionally, the contact angle is found to be dependent on particle size and temperature even below the eutectic temperature of the Au-Si alloy. Molecular dynamics simulations were performed to investigate potential explanations for such experimental observation. In this temperature regime, the simulations reveal the formation of an amorphous phase at the interface between the catalyst and SiNW that is sensitive to temperature. This amorphous layer increases the adhesion energy at the interface and explains the contact angle dependence on temperature. Published by AIP Publishing.

• 出版日期2016-11-21