Polycrystalline Diamond RFMEMS Resonators with the Highest Quality Factors

This paper reports the highest quality factor (Q) of 116,000 for cantilever beams made from any polycrystalline material, which is also the highest Q for any resonator structure made of polycrystalline diamond (poly-C). These results also include the highest Q of 47,900 for a highly-doped (0.15 Ohm-cm) poly-C resonator structure. A study of the energy dissipation mechanisms was performed in order to understand what limits the Q in poly-C resonators. The results obtained in this work show a decrease in Q with increasing doping level and grain boundaries. The poly-C cantilevers were tested at different temperatures in order to identify a possible thermally activated relaxation process responsible for limiting the Q. The activation energy found for this defect relaxation process is about 1.9 eV. The structures were tested using piezoelectric actuation and light scattering-interferometer detection techniques described elsewhere [ 1].