| AVS 54th International Symposium | |
| Nanometer-scale Science and Technology | Thursday Sessions |
| Session NS-ThA |
| Session: | Nanoscale Sensors |
| Presenter: | M. Belov, University of Alberta, Canada |
| Authors: | M. Belov, University of Alberta, Canada N.J. Quitoriano, Hewlett-Packard Laboratories S. Sharma, Hewlett-Packard Laboratories T.I. Kamins, Hewlett-Packard Laboratories S. Evoy, University of Alberta, Canada |
| Correspondent: | Click to Email |
Highly-sensitive transducers for the detection and assaying of molecular systems based on nanomechanical beams have been proposed. Mechanical objects with lateral dimensions reaching the sub-100 nm range, with high resonant frequencies and quality factors, are now routinely fabricated using surface micromachining. The surface machining procedures employed in NEMS fabrication are inherently slow, offer limited yield and usually employ plasma-assisted etching techniques that may introduce surface damage and significantly change the mechanical properties of the resonating element. The direct growth of cantilevered nanowires by chemical vapor deposition methods (CVD) offers, alternatively, a potent way for the efficient production of high-quality NEMS resonators, with sub-50nm diameters, circular profiles and small clamping losses. We report the synthesis and characterization of vibrating silicon nanowires grown by CVD. These highly-oriented and clamped silicon structures were laterally grown from the sides of etched silicon posts using a metal-catalyzed chemical vapor deposition process. The diameters and lengths of the structures ranged from 40 to 400 nanometers and from 2 to 20 micrometers, respectively. The substrates were mounted onto a piezoceramic disc, installed in a vacuum chamber and actuated at varying frequencies. The laser beam focused onto the vibrating structure was reflected back and the detected signal, proportional to the deflection of the beam relatively to the substrate, was processed by a spectrum analyzer. The data were acquired at temperatures ranging from 77°K up to 293°K, and at pressures ranging from atmospheric down to the low 10-6 Torr. Typical resonant frequencies ranged from 1 to 20 MHz, in agreement with the Euler-Bernoulli analysis of vibrating structures. The resonant frequency of the nanowires typically showed a 0.25% increase as the nanowires were cooled from T = 293°K to T = 77°K as a result of changing Young´s modulus. We also measured qualities of the resonators over the same temperature range. We discuss the energy dissipation processes that dominate the performance of these devices at various temperatures and pressures. This work was partially supported by Alberta Innovation and Science and by Hewlett-Packard Laboratories.