Combined Experimental and Computational Methods Reveal the Evolution of Buried Interfaces during Synthesis of Ferroelectric Thin Films

Abstract

(1 of 10) 1500181 wileyonlinelibrary.com IntroductionFerroelectric thin fi lms have broad application in society ranging from nonvolatile memories to microrobotics and integrated capacitors. As the sizes of devices and the thicknesses of fi lms decrease, the specifi c surface and interfacial areas increase signifi cantly. At these progressively smaller length scales, interfacial phenomena such as interdiffusion and interface reactions are promoted and can have benefi cial or deleterious consequences on the resultant fi lm and device properties and functionality. [1][2][3][4] Thus, an understanding of interfacial phenomena between dissimilar materials is of paramount importance in materials and devices of small length scale.Solution-based chemical routes have become effective for the synthesis of ferroelectric lead zirconate titanate (PZT) thin fi lms on diverse substrates. [5][6][7][8] In these routes, a solution is spin cast on a substrate and then subsequently heated to induce crystallization of the ferroelectric fi lm. For Pb-based ferroelectric fi lms Understanding interfaces between dissimilar materials is crucial to the development of modern technologies, for example, semiconductor-dielectric and thermoelectric-semiconductor interfaces in emerging electronic devices. However, the structural characterization of buried interfaces is challenging because many measurement techniques are surface sensitive by design. When interested in interface evolution during synthesis, the experimental challenges multiply and often necessitate in situ techniques. For solution-derived lead zirconate titanate (PZT) ferroelectric thin fi lms, the evolution of buried interfaces during synthesis (including dielectricmetal and metal-metal) is thought to dramatically infl uence the resultant dielectric and ferroelectric properties. In the present work, multiple experimental and computational methods are combined to characterize interface evolution during synthesis of ferroelectric PZT fi lms on platinized Si wafers-including in situ X-ray diffraction during thermal treatment, aberration-corrected scanning transmission electron microscopy of samples quenched from various synthesis states, and calculations using density functional theory. Substantial interactions at buried interfaces in the PZT/Pt/Ti/SiO x /Si heterostructure are observed and discussed relative to their role(s) in the synthesis process. The results prove that perovskite PZT nucleates directly from the platinum (111)-oriented bottom electrode and reveal the roles of Pb and O diffusion and intermetallic Pt 3 Pb and Pt 3 Ti phases.

High‐energy storage density and excellent temperature stability in antiferroelectric/ferroelectric bilayer thin films

“…The seminal study focused on the orientation of PZT films was investigated by Chen et al., it was reported that the (111)‐oriented PZT films was induced by the formation of PtPb intermetallic phase . However, the recent study have provided a more intuitive evidence for elucidating that (111)‐oriented PZT films nucleates directly on Pt(111) bottom electrode . Our previous studies have indicated that the preferential orientation of PZT film on Pt(111) substrate was induced by the coherent growth of PZT film due to the lattice mismatch between the PZT film and Pt(111) substrate .…”

High energy storage efficiency and thermal stability of A‐site‐deficient and 110‐textured BaTiO3–BiScO3 thin films

“…Earlier studies on Pb‐based ferroelectric thin films showed similar development of a (111) preferred orientation for an annealing temperature above 550°C, which was attributed to heteroepitaxial growth on transient intermetallic Pt 3 Ti . This view was, however, disputed in a more recent study, indicating that perovskite PZT layers grow directly on platinum substrates . The degree of heteroepitaxial growth of perovskite layers can depend on the amount of intermetallic phases on the surface and their exact interaction with the deposited species.…”

“…45,46 This view was, however, disputed in a more recent study, indicating that perovskite PZT layers grow directly on platinum substrates. 47 The degree of heteroepitaxial growth of perovskite layers can depend on the amount of intermetallic phases on the surface and their exact interaction with the deposited species. Similar to the growth of Pb-based films, it may be possible that, for BaTiO 3 -BiScO 3 films, transient Pt-Ti and Bi-Pt intermetallic phases are formed at the interface with the bottom electrode.…”

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

“…In a previous study, the work of adhesion of the PZT(111)/Pt(111) and PZT(111)/Pt 3 Pb(111) interfaces was investigated as a function of PZT termination . The results indicated that the interfaces with Ti‐terminated PZT have the lowest relative adhesion energies .…”

“…Recently, Jones and coworkers utilized in situ X‐ray diffraction to characterize the evolution of PZT during crystallization . They monitored the formation and disappearance of Pt 3 Pb phase at the PZT/Pt interface, a secondary phase that would be undesirable for device functionality . Specifically, Pt 3 Pb was detected during the PZT formation and found to disappear before the PZT was fully crystallized.…”