Highly Oriented, Chemically Prepared Pb(Zr, Ti)O₃ Thin Films

Abstract

We have fabricated highly oriented, chemically prepared thin films of Pb(Zr,,aTio,m)03 (PZT 40/60) on both insulating and conducting substrates. While (100) MgO single crystals were used as the insulating substrates, the conducting substrates were fabricated by RF magnetron sputter deposition of 100-nm-thick (100) Pt films onto (100) MgO substrates. For comparison, we also fabricated PZT 40/60 films that had no significant preferential orientation on platinized MgO substrates. Sputter deposition of an underlying amorphous Pt film was used to fabricate randomly oriented PZT 40/60 films. Highly (001) oriented PZT 40/60 films had higher remanent polarization (61 pC/cm2 compared to 41 pC/cm2) and lower relative dielectric constant (368 compared to 466) than PZT 40160 films that were randomly oriented.

Sintering of sol-gel films

“…Orientation can reportedly be improved by imposing a temperature gradient, so that the substrate heats first [63]. It is also advantageous to work with thinner layers, since that reduces the volume in which homogeneous nucleation can occur; for example, Barb6 et al [68] obtained good orientation in a multilayer deposit of potassium titanyl phosphate if each layer was fired before the next was applied; however, if several layers were deposited and fired together, unoriented polycrystalline films resulted.…”

“…When Ti was deposited on Pt, it formed a Pt3Ti alloy that has close matching of the Ti positions with PLZT, and that led to enhanced orientation; if the Ti was oxidized by prior heat-treatment, the orientation was degraded. Similarly, Tuttle et al [63] obtained epitaxial PZT by depositing directly onto MgO single crystals, but randomly oriented films developed if random Pt films were deposited onto the MgO. In some cases, techniques such as laser ablation or ion beam deposition are used to provide "template" layers that control the orientation and phase of the sol-gel film [64].…”

Ferroelectric properties of sol-gel delivered epitaxial Pb(Zrx,Ti1−x)O3 thin films on Si using epitaxial γ-Al2O3 Layers

“…7 Accordingly, utilization of ferroelectric films with properly controlled crystalline orientations is essential for device applications. Although sol-gel derived oriented and epitaxial thin films of lead-based ferroelectric materials have been reported, [8][9][10][11][12] there have been few studies of the preparation and properties of sol-gel derived PZT thin films with nearsingle-crystal qualities. Crystallinity and orientation of substrates are very important in the control of orientation of bottom electrode and PZT films, and MgO single crystal substrates and SrTiO 3 single crystal substrate have been reported.…”

X-Ray Texture Analysis of Oriented PZT Thin Films

“…In order to maximize the remanent polarization a (001) and (111) texture are desired for the tetragonal and rhombohedral phases of PZT, respectively. Several research groups have demonstrated that the substrate material [1], orientation [1,2], PZT composition (Ti:Zr ratio) [3,4], and subsequent heating schedule [1][2][3][4][5][6][7][8] can all influence the texture of polycrystalline PZT thin films. Specifically, the pyrolysis and rapid thermal processing steps appear to have a significant influence on the final film orientation, and consequently, the ferroelectric properties.…”