Nanomechanical Resonant Devices: Surface Chemistry, Challenges, and Opportunities
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The sensitivity of nanomechanical resonant sensors to the applied mass or force is determined in part by their quality factor or Q—a dimensionless quantity that is inversely proportional to the rate of mechanical energy dissipation in the sensor. The Q of megahertz-range silicon resonators is shown to be surprisingly sensitive to surface chemistry; by changing one monolayer on the surface of a 250 nm-thick device, the rate of mechanical energy dissipation can be increased by at least a factor of 2. The chemical dependence of this effect and possible mechanisms are discussed.