Pyroelectric response of lead zirconate titanate thin films on silicon: Effect of thermal stresses

Abstract

Author(s)Kesim, M. T.; Zhang, J.; Trolier-McKinstry, S.; Mantese, J. V.;Whatmore, Roger W.; Alpay, S. P. Ferroelectric lead zirconate titanate [Pb(Zr x Ti 1-x O) 3 , (PZT x:1-x)] has received considerable interest for applications related to uncooled infrared devices due to its large pyroelectric figures of merit near room temperature, and the fact that such devices are inherently ac coupled, allowing for simplified image post processing. For ferroelectric films made by industry-standard deposition techniques, stresses develop in the PZT layer upon cooling from the processing/growth temperature due to thermal mismatch between the film and the substrate. In this study, we use a non-linear thermodynamic model to investigate the pyroelectric properties of polycrystalline PZT thin films for five different compositions (PZT 40:60, PZT 30:70, PZT 20:80, PZT 10:90, PZT 0:100) on silicon as a function of processing temperature (25-800 C). It is shown that the in-plane thermal stresses in PZT thin films alter the out-of-plane polarization and the ferroelectric phase transformation temperature, with profound effect on the pyroelectric properties. PZT 30:70 is found to have the largest pyroelectric coefficient (0.042 lC cm À2 C Publication date 2013 Original citation À1, comparable to bulk values) at a growth temperature of 550 C; typical to what is currently used for many deposition processes. Our results indicate that it is possible to optimize the pyroelectric response of PZT thin films by adjusting the Ti composition and the processing temperature, thereby, enabling the tailoring of material properties for optimization relative to a specific deposition process. V C 2013 AIP Publishing LLC. [http://dx

Ferroelectrics: A pathway to switchable surface chemistry and catalysis

“…Also, while the compensating charges eliminate the thickness-dependent component of the dipole, surface dipoles remain which can aect adsorption of polar molecules [31]. Ferroelectrics are a class of materials that have a spontaneous electric polarization vector (an order parameter) whose direction can be switched using an electric eld and whose magnitude is temperature-controlled through the pyroelectric eect 2 [32,33]. The modications of ferroelectric surfaces due to the compensation of the surface charge density via adatoms, vacancies, surface dipoles and changes in surface electron density can all, in principle, alter the surface chemistry.…”

Si integrated ferroelectric MEMS sensors using epitaxial PZT thin films on γ-Al2O3/Si substrates

“…Numerous researches about improvement of electrical properties of PZT films on Si substrates have been reported with composition, orientation, and process condition controls while typical PZT films are deposited as randomly oriented poly-crystalline films because of their simple fabrication processes [8][9][10].…”

Diffusion Across M/Pb(Zr,Ti)O3 Interfaces (M=Pt3Pb or Pt) Under Different System Conditions

“…[4][5][6] High-quality PZT films with desired texture are fabricated using a variety of processes [7][8][9][10] including chemical solution deposition (CSD), 5,7 which is a rapid and inexpensive approach. 11 The final structure and the features of the film [12][13][14] have been reported to play a crucial role in controlling the performance and characteristics of the resulting devices. In particular, the (111) oriented PZT thin film exhibits the most desired properties and is one of the most extensively discussed in the literature.…”