Metalorganic Chemical Vapor Deposition of Ferroelectric Pb(Zr,Ti)O3 Thin Films

Abstract

Ferroelectric Pb(ZrxT1–x)O3, films were successfully and reproducibly deposited by both hot–wall metalorganic chemical vapor deposition (MOCVD) and cold‐wall MOCVD. One of the important problems associated with the MOCVD techniques is the selection of ideal precursors. After an intensive investigation for the most suitable precursors for MOCVD PZT films, the safe and stable precursors, namely lead tetramethylheptadione [Pb(thd)2], zirconium tetramethylheptadione [Zr(thd)4], and titanium ethoxide [Ti(OEt)4], were chosen. The films were deposited at temperatures as low as 550°C and were single‐phase perovskite in the as‐deposited state. Also, the films were smooth, specular, crack‐free, and uniform, and adhered well to the substrates. The stoichiometry of the films can be easily controlled by varying the individual precursor temperature and/or the flow rate of the carrier gas. Auger electron spectroscopic (AES) depth profile showed good compositional uniformity through the thickness of the films. The AES spectra also showed no carbon contamination in the bulk of the films. As‐deposited films were dense and showed uniform and fine grains (≅0.1 μm).The optical properties of the films on the sapphire disks showed high refractive index (n= 2.413) and low extinction coeflicient (k= 0.0008) at a wavelength of 632.8 nm. The PZT (82/18) film annealed at 600°C showed a spontaneous polarization of 23.3 μC/cm2 and a coercive field of 64.5 kV/cm.