Processing and properties of high aspect ratio ferroelectric structures

High aspect ratio (≥50:1) ferroelectric structures are potentially applicable in areas such as tunable photonic devices, sensors and actuators. In this work high aspect ratio structures of Pb(Zr_x, Ti_1-x)O₃, and LaNiO₃/Pb(Zr_x,Ti_1-x)O₃/LaNiO₃ tri-layers were prepared by vacuum infiltration of meso-porous Si templates. Pyrolysis was done at 300°C for 2 min. Reactive ion etching followed by XeF₂ isotropic Si etching was utilized to release the embedded PZT structures from the Si template. The released structures were annealed at 700°C for 1 min. in order to induce crystallization. These 2D ferroelectric photonic structures exhibited a TE-mode band gap in the infrared region between 4.0 - 4.4 microns in wavelength, which was found to be consistent with the theoretical photonic band gap calculations.