Direct integration of CNT forests on solidly mounted resonators and their influence on device performance

Carbon nanotubes (CNTs) have been typically employed as active layers in sensors, however their vertically-aligned (forest) morphology has not been fully explored yet. Here we directly integrate CNT forests on AlN-based solidly mounted resonators and study their influence on the performance of the longitudinal and shear mode of operation. Results show that CNT forests induce quality factor degradation and that too tall forests lead to excessive degradation of the frequency response. A trade-off between device performance and surface area increase for better sensing can be found with forests of heights lower than ~ 10 μm. Additionally, we show that the shear mode is less degraded than the longitudinal mode and that multi-walled CNTs degrade in less extend the devices.