Quality factor issues in silicon carbide nanomechanical resonators

Nanomechanical resonators with fundamental mode resonance frequencies in the Very-High Frequency (VHF), Ultra-High Frequency (UHF) range and microwave L-band are fabricated from monocrystalline silicon carbide thin film material, and measured by magnetomotive transduction, combined with a balanced bridge read out circuit. For resonators made from the same film, we measured the frequency (i.e., geometry) dependence of the quality factor. It is found that the quality factor of these resonators decreases when the frequency increases. This indicates the importance of clamping loss in this regime. In addition, from studies of resonators made from different chips with varying surface roughness, we found a strong correlation between surface roughness of the silicon carbide thin film material and the quality factor of the resonators made from it. Understanding the dissipation mechanisms, and thus improving the quality factor of these resonators, is important for implementing applications promised by these devices.