| AVS 55th International Symposium & Exhibition | |
| MEMS and NEMS | Monday Sessions |
| Session MN-MoM |
| Session: | Integrative Materials and Processes for MEMS/NEMS |
| Presenter: | M.K. Zalalutdinov, SFA Inc. |
| Authors: | M.K. Zalalutdinov, SFA Inc. J.T. Robinson, Naval Research Laboratory E.S. Snow, Naval Research Laboratory Z. Wei, Naval Research Laboratory P.E. Sheehan, Naval Research Laboratory J.W. Baldwin, Naval Research Laboratory B.H. Houston, Naval Research Laboratory |
| Correspondent: | Click to Email |
High quality factor (Q~4000) radio frequency (20-100 MHz) nanomechanical resonators are fabricated using suspended ultra-thin films of chemically modified graphene (CMG).1 The films were prepared by spin-casting graphene oxide platelets onto SiO2/Si substrates, reducing back toward graphene using chemical and/or thermal treatments, then lifting-off and transferring films to patterned substrates. Large-area continuous films can be deposited using this method, enabling batch fabrication of nanoelectromechanical devices. Membranes as thin as 4 nm can be successfully transferred and suspended over 2.7 µm diameter holes. The ability to withstand high in-plane tensile stress (T~10 N/m, deduced from membrane resonant frequencies) as well as high quality factors show that the integrity of the film is NOT compromised by the inter-platelet bonding. The extremely small mass of these CMG resonators provides an estimate for the added mass sensitivity as low as δm~10-18 g. In-plane stress inherent to as-fabricated CMG membranes can be dynamically tuned over a wide range due to thermoelastic effects by applying a low power localized heat source. In conjunction with the short thermal relaxation time (τ~10-8 sec) this enables techniques such as parametric pumping for further enhancement of the performance of CMG resonators. Thicker (h>15 nm) suspended CMG films show similar quality factors, can withstand strain in excess of 0.3% and constitute a virtually unpenetrateable barrier for water or vapor as confirmed by resonant frequency measurements. Membranes encapsulating water on one side and exposed to vacuum on the other side show no frequency dependence on a time scale of days, indicating perfect sealing. In addition, both the membranes themselves and the adhesion of the CMG film to the substrate are strong enough to withstand boiling of the encapsulated water (Tanneal>100°C). Finally, ultra-thin CMG films are optically transparent and feature only minor e-beam scattering thereby facilitating access to encapsulated objects for imaging and/or spectroscopy. We will describe mechanical and thermomechanical properties of CMG films extracted from the behavior of the nanoresonators and discuss possible applications in sensing and nanofluidics.
This work was supported by the Office of Naval Research.
1 Ruoff, R. Nature Nanotechnology 3, 10-11 (2008).