Room temperature relaxation of freestanding nanocrystalline gold films

Abstract

We present a novel experimental technique to study compound stress–strain relaxation of thin freestanding gold films at room temperature. The films were 125 nm thick with an average grain size of 50–60 nm. Both static experiments and time-dependent relaxation experiments were performed inside a field emission scanning electron microscope using a micro- electromechanical system (MEMS)-based test bed which is only 3 mm × 10 mm in size. The thin film specimens used in these experiments are co-fabricated with the micromechanical loading device and hence do not need to be externally aligned and gripped. We observed a significant effect of stress relaxation on Young's modulus of gold thin films and modeled the relaxation behavior using a three-parameter standard anelastic solid. The freestanding nature of the thin film also provides us with information about the mechanical behavior of thin films without any substrate effects.