Correlation of composition with mechanical and electrical performances in thermally stable Au-ZnO nanocomposite films

Abstract

Metal thin films have traditionally been strengthened and stabilized by alloying with another metal, but this method causes a pronounced increase in electrical resistivity. This study found that oxide additions could effectively enhance the thermal stability and hardness of metals with only a small increase in their resistivity. An oxide particle-strengthened Au-ZnO nanocomposite film was developed, which exhibited excellent thermal stability as high as 450 °C and high hardness twice that of pure gold (Au). Upon high-temperature annealing, the Au-ZnO nanocomposite film maintained twice the hardness of the pure Au film (3.2 GPa). Concurrently, the resistivity of the Au-ZnO nanocomposite film decreased significantly to as low as 9.82 × 10⁻⁸ Ω-m, approaching the resistivity of pure Au (5.08 × 10⁻⁸ Ω-m). A model captured the changes in hardness and electrical resistivity as a function of ZnO content, revealing the correlation between the composition of the Au-ZnO nanocomposite films and their mechanical and electrical properties. This study demonstrated that the small amount of ZnO required to strengthen the pure Au film could improve its thermal stability while causing minimal changes to its electrical resistivity, which was essential for developing high-performance coatings used in micro-electro-mechanical systems devices.