Lead Zirconate Titanate (PZT) is widely used for energy harvesting owing to its strong piezoelectric and electromechanical coupling coefficient as well as high temperature compatibility (Curie point ~ 370°C).1-3 The heterogeneous integration of a PZT thin film on the Si photonics platform can compensate the lack of piezoelectricity in the centro-symmetric Silicon, and enable a wide range of electro-optomechanical applications combining the benefits of a strong piezoelectric material and a matured photonic platform.
In this work, we directly deposit a PZT film on silicon-on-insulator (SOI) using a transparent Lanthanide based seed layer making it photonics compatible,4 unlike the traditional PZT film grown with a metallic Platinum (Pt) buffer layer, which introduces unacceptable optical losses in the device.5 We fabricate unimorph micro- cantilever beams with the hybrid PZT-SOI chip and demonstrate its piezoelectric actuation. The laser Doppler Vibrometry (LDV) measurements on these suspended actuators give a deflection up to 40 nm with an applied RF voltage of Vpp = 10 V at the fundamental resonance frequency. Next, through numerical simulations, we show that a PZT actuator integrated with a directional coupler allows for a strong tuning efficiency.
Thus, we demonstrate a PZT film based actuator that can be directly integrated on the Si photonic plat- form. This opens the possibility of achieving an efficient electro-optomechanical coupling and low-power MEMS applications in Si photonic integrated circuits (PICs).
