LiNbO3 Thin Films through a Sol-Gel/Spin-Coating Approach Using a Novel Heterobimetallic Lithium-Niobium Precursor.

Lithium niobate is a lead-free material which has attracted considerable attention due to its excellent optical, piezoelectric, and ferroelectric properties. This research is devoted to the synthesis through an innovative sol-gel/spin-coating approach of polycrystalline LiNbO3 films on Si substrates. A novel single-source hetero-bimetallic precursor containing lithium and niobium was synthesized and applied to the sol-gel synthesis. The structural, compositional, and thermal characteristics of the precursor have been tested through attenuated total reflection, X-ray photoelectron spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The LiNbO3 films have been characterized from a structural point of view with combined X-ray diffraction and Raman spectroscopy. Field-emission scanning electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy have been used to study the morphological and compositional properties of the deposited films.

Microfabrication of piezoelectric MEMS based on thick LiNbO3single-crystal films.

Microfabrication procedure of piezoelectric micro electro-mechanical systems based on 5µm thick LiNbO3films on SiO2/Si substrate at wafer scale including deep dry etching of thick LiNbO3films by implementing pulsed mode of Ar/SF6gas was developed. In particular, two (YXlt)/128°/90°LiNbO3-Si cantilevers with tip mass were fabricated and characterized in terms of resonance frequency (511 and 817 Hz), actuation and acceleration sensing capabilities. The quality factor of 89.5 and the electromechanical coupling of 4.8% were estimated from measured frequency dependency of electrical impedance, fitted by using Butterworth-Van Dyke model. The fabricated piezoelectric micro-electro-mechanical systems have demonstrated highly linear displacement with good sensitivity (5.28 ± 0.02µm V-1) as a function of applied voltage and high sensitivity to vibrations of 667 mV g-1indicating a suitability of the structure for actuation purposes and for acceleration or frequency sensing with high precision, respectively.

Piezoelectric BiFeO3 Thin Films: Optimization of MOCVD Process on Si.

This paper presents a simple and optimized metal organic chemical vapor deposition (MOCVD) protocol for the deposition of perovskite BiFeO3 films on silicon-based substrates, in order to move toward the next generation of lead-free hybrid energy harvesters. A bi-metal mixture that is composed of Bi(phenyl)3, and Fe(tmhd)3 has been used as a precursor source. BiFeO3 films have been grown by MOCVD on IrO2/Si substrates, in which the conductive IrO2 functions as a bottom electrode and a buffer layer. BiFeO3 films have been analyzed by X-ray diffraction (XRD) for structural characterization and by field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray (EDX) analysis for the morphological and chemical characterizations, respectively. These studies have shown that the deposited films are polycrystalline, pure BiFeO3 phase highly homogenous in morphology and composition all over the entire substrate surface. Piezoelectric force microscopy (PFM) and Piezoelectric Force Spectroscopy (PFS) checked the piezoelectric and ferroelectric properties of the film.