Thin-film piezoelectric bimorph actuators with increased thickness using double Pb[Zr,Ti]O₃layers

Abstract

We studied the effects of increasing the thickness of bimorph structures containing double layers of Pb(Zr,Ti)O3 (PZT) thin films. Thick PZT films allow high-voltage application (e.g. in terms of coercive electric field and breakdown voltage) and large generative force, which are effective in microelectromechanical systems (MEMS) applications. Improvement of the deposition conditions and electrode structures facilitates the fabrication of the thin-film PZT/PZT bimorph structure. The PZT/PZT bimorph with a total thickness of 5.8 µm, deposited using a radio-frequency (RF) magnetron sputtering system is much thicker than conventional bimorph structures. The characteristics of the two piezoelectric layers were similar to each other and revealed good electric and ferroelectric characteristics with a remanent polarization of 20 µC cm−2 and a coercive electric field of 50 kV cm−1. PZT/PZT bimorph cantilevers were fabricated in order to evaluate their characteristics for actuator applications. The residual stress of the bimorph cantilever was reduced by an annealing process. The vibration test on the fabricated bimorph cantilevers during electrical voltage application revealed a twice as large displacement as compared with a single layer actuation, and the piezoelectric coefficient value d31 was estimated to be −61 pm V−1, which is better than the value of conventional PZT/PZT bimorph cantilevers (−13 pm V−1). It was also shown that the influence of the temperature change is much less than that in unimorph structures with similar dimensions. The evaluated results demonstrate that the PZT/PZT bimorph structures are effective as MEMS devices.

Multilayer Pb(Zr,Ti)O3 Thin Films for Ultrasonic Transducer

“…Much R&D is done on cMUTs due to their fitness to semiconductor processes, but high driving voltage is a problem. We succeeded in multilayer film fabrication using lead zirconate titanate (PZT: Pb(Zr,Ti)O 3 ) with excellent piezoelectric properties, and confirmed good piezoelectric characteristics in every layer [6,7]. If thin-film piezoelectric materials could be used, then fitness to MEMS batch processes would be improved, while sensitivity and directivity could be increased by arraying, and smaller devices could be expected.…”

“…In our previous research [6,7], we fabricated laminated PZT thin films of two to six layers using Radio …”

Efficient Piezoelectric Energy Harvesters Utilizing (001) Textured Bimorph PZT Films on Flexible Metal Foils

“…To measure the performance of the PCM device, the top electrode of the upper and lower PZT layers were wired in series and connected to a resistor box to tune the load resistivity. [ 25 ] The mechanical damping ratio, ζ = ( f bf a )/2 f r , was 2.07%. A video showing device operation under resonant excitation is shown in Video S1 of the Supporting Information.…”

“…[ 1,2 ] However, mechanical energy harvesting is faced by challenges such as weak base excitations with low natural frequency (<10 Hz) [ 3,4 ] and fragile structures that are susceptible to shock. [ 2,25 ] A PCM energy harvester consists of three parts, as shown schematically in Figure 1 . Numerous methods to improve the output power cantilevers undergo larger strains compared to bridges, for the same input force, the strain distribution along the piezoelectric beam is not uniform.…”

Two-Time Scale Virtual Sensor Design for Vibration Observation of a Translational Flexible-Link Manipulator Based on Singular Perturbation and Differential Games

“…However, owing to the feeble rigidity and heavy deflection, the flexible manipulator easily produces elastic deformation and vibration during operation, which has a terrible effect on the position precision, stability, and service life of the whole system. Thus, it is of vital significance to investigate the vibration characteristics and active vibration control strategy of the flexible manipulator [8]. …”