High-frequency micromechanical resonators from aluminium-carbon nanotube nanolaminates

At micro- and nanoscales, materials with high Youngs moduli and low densities are of great interest for high-frequency micromechanical resonator devices. Incorporating carbon nanotubes (CNTs), with their unmatched properties, has added functionality to many man-made composites. We report on the fabrication of 100-nm-thick laminates by sputter-deposition of aluminium onto a two-dimensional single-walled CNT network. These nanolaminatescomposed of Al, its native oxide Al"2O"3 and CNTsare fashioned, in a scalable manner, into suspended doubly clamped micromechanical beams. Dynamic flexural measurements show marked increases in resonant frequencies for nanolaminates with Al-CNT laminae. Such increases, further supported by quasi-static flexural measurements, are partly attributable to enhancements in elastic properties arising from the addition of CNTs. As a consequence, these nanolaminate micromechanical resonators show significant suppression of mechanical nonlinearity and enhanced strength, both of which are advantageous for practical applications and analogous to biological nanocomposites, similarly composed of high-aspect-ratio, mechanically superior mineral platelets in a soft protein matrix.