Synthesis and characterization of Au-Ta nanocomposites for nanomechanical cantilever devices

Abstract

A gold-tantalum nanocomposite material synthesized using a co-sputtering technique and designed specifically for nanomechanical systems applications is reported. X-ray diffraction, atomic force microscopy, scanning electron microscopy, nanoindentation and four-point probe contact measurements were performed to characterize the bulk and surface characteristics of the films. The films exhibited an increased reduced modulus and hardness as well as a significant grain size reduction while retaining the face-centered cubic (FCC) structure of pure gold with a very strong texture. In addition, the mechanical characterization of a number of 800 nm wide, 50 nm thick Au-5 at.% Ta cantilevers was performed using optical interferometry. Such devices exhibited resonant frequencies ranging from 371 kHz to 10.9 MHz, with resonant qualities as high as Q = 640.