Aluminum Nitride Out-of-Plane Piezoelectric MEMS Actuators

Abstract

Integrating microelectromechanical systems (MEMS) actuators with low-loss suspended silicon nitride waveguides enables the precise alignment of these waveguides to other photonic integrated circuits (PICs). This requires both in-plane and out-of-plane actuators to ensure high-precision optical alignment. However, most current out-of-plane electrostatic actuators are bulky, while electrothermal actuators consume high power. Thus, piezoelectric actuators, thanks to their moderate actuation voltages and low power consumption, could be used as alternatives. Furthermore, piezoelectric actuators can provide displacements in two opposite directions. This study presents a novel aluminum nitride-based out-of-plane piezoelectric MEMS actuator equipped with a capacitive sensing mechanism to track its displacement. This actuator could be integrated within PICs to align different chips. Prototypes of the device were tested over the range of ±60 V, where they provided upward and downward displacements, and achieved a total average out-of-plane displacement of 1.30 ± 0.04 μm. Capacitance measurement showed a linear relation with the displacement, where at −60 V, the average change in capacitance was found to be −13.10 ± 0.89 fF, whereas at 60 V the change was 11.09 ± 0.73 fF. This study also investigates the effect of the residual stress caused by the top metal electrode, on the linearity of the displacement–voltage relation. The simulation predicts that the prototype could be modified to accommodate waveguide routing above it without affecting its performance, and it could also incorporate in-plane lateral actuators.

Origin of the negative longitudinal piezoelectric effect and electric auxetic effect in hexagonal AIBIVCV semiconductors

“…Among the 18 compounds covered in this study, we identify 11 compounds (LiGeN, NaGeN, KGeN, KGeP, LiSnN, NaSnN, NaSnP, NaSnAs, KSnN, KSnP, and KSnAs) with the NLPE. Moreover, we note that the calculated | d 33 | values of 4 compounds (10.05 pC N −1 for NaGeSb, 8.68 pC N −1 for KGeSb, −9.61 pC N −1 for LiSnN, and 7.41 pC N −1 for KSnSb) are comparable in magnitude to that of AlN (a typical piezoelectric material that is widely used as energy harvesters 59 and sensors 60 due to its high d 33 of 5.5 pC N −1 61 ), and hence these materials may have potential applications in electromechanical devices such as piezoelectric actuators 62 due to their relatively large piezoelectric response. It is worth mentioning that the d 33 is related to the e ij via the elastic compliance tensor C ij (), and hence the difference in the | d 33 | may be substantial especially for compounds with a large | d 33 | such as NaGeSb and KGeSb ( d 33 = 10.05 pC N −1 for NaGeSb; d 33 = 8.68 pC N −1 for KGeSb,) even though they are chemically similar (for NaGeSb, Δ χ = 0.71; for KGeSb, Δ χ = 0.73), as shown in Fig.…”

Editorial for the Special Issue on Piezoelectric Transducers: Materials, Devices and Applications, Volume III

“…Also included herein is a research paper about out-of-plane piezoelectric MEMS actuators equipped with a capacitive sensing mechanism to track its displacement, where the measured capacitance shows a linear relationship with the displacement [20]. Rotary and linear ultrasonic motors are also covered in various papers, which discuss, for example, the design, fabrication and characterization of cooperative microactuators featuring hybrid planar conveyance systems based on piezoelectric MEMS resonators with attached 3D-printed legs, demonstrating their application as fast, low-energy conveyors for reconfigurable electronics [21], or a new type of hybrid drive motor combining the characteristics of electromagnetic drive and piezoelectric drive devices [22,23].…”