RETAINING HIGH Q FACTORS IN ELECTRODE-LESS AlN-ON-Si BULK MODE RESONATORS WITH NON-CONTACT ELECTRICAL DRIVE

This paper reports on an experimental study of actuation techniques of aluminum nitride on silicon (AlN/Si) heterostructure resonant microelectromechanical systems (MEMS) with both bulk and flexural modes, and comparison of their quality factors (Qs) and energy losses induced by different resonant motion excitation schemes. For AlN/Si MEMS resonators without deposited top metal electrodes, we have devised a new scheme to electrically drive the device, enabled by a non-contact overhanging electrode inducing gradient forces, to replace the otherwise required optical excitation for electrode-less devices. For the bulk mode resonance of AlN/Si resonator at 10MHz, almost equal Q of similar to 26,000 is obtained for both the new electrical drive and the optical drive, whereas the electrical drive enables the detection of a similar to 1MHz mode that is not visible when driven optically. For the Si-only device, Q of 257,300 is attained with the non-contact electrical drive, noticeably higher than the Q of 212,225 with the optical drive, suggesting that non-contact electrical excitation results in lower energy dissipation than optical actuation. The present work motivates further studies of transduction mechanisms to achieve higher resonator Qs.

Automated summary

This paper reports on an experimental study of actuation techniques for AlN/Si heterostructure resonant MEMS and compares their quality factors and energy losses. A new scheme with non-contact overhanging electrode inducing gradient forces is developed to electrically drive the devices. The electrical drive enables the detection of unseen resonant modes and results in lower energy dissipation compared to the optical drive.