Unusual Scaling Observations in the Quality Factors of Cantilevered Carbon Nanotube Resonators

This work examines the quality factors (Q factors) of resonance associated with the axial and transverse vibrations of single-wall carbon nanotube (SWCNT) resonators through the use of molecular dynamics (MD) simulation. Specifically, the work investigates the effect of device length, diameter, and chirality, as well as temperature, on the resonant frequency and quality factor of these devices, and benchmarks the results of MD simulation against classical theories of energy dissipation. Of note are the facts that the quality factors associated with transverse vibration decrease with increasing device diameter and are largely insensitive to chirality. Additionally, quality factors increase with increasing device length for transverse vibrations, but remain almost constant for axial vibrations. The predicted size dependence of the quality factors associated with axial vibration agrees well with classical theory, if the nanoscale size effect of thermal conductivity is properly accounted for. However, the size dependence of the quality factors associated with transverse vibrations deviates significantly from classical theory.