Giant effective pyroelectric coefficients from graded ferroelectric devices

Jin, Fei; Auner, Gregory W.; Naik, R.; Schubring, Norman W.; Mantese, J. V.; Catalan, Antonio B.; Micheli, Adolph L.

doi:10.1063/1.122607

Cited by 119 publications

(76 citation statements)

References 10 publications

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“…Figure 3 also reveals that it is possible to improve upon the pyroelectric performance of bulk which has been reported for FE films and heterostructures in previous studies. 6,[56][57][58] The high pyroelectric response of the PZT 30:70 can be explained because the phase transformation temperature is sufficiently remote from RT to achieve a relatively large polarization, yet at the same time close enough to allow substantial polarization change with temperature. We note that experimentally PZT films on Si substrates contain polydomain microstructures that form so as to relax thermal stresses due to the TEC mismatch and the transformational stresses due to the FE-PE phase transformation at T C .…”

Section: Resultsmentioning

confidence: 99%

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

Kesim

Zhang

Trolier-McKinstry

et al. 2013

Journal of Applied Physics

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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

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Section: Resultsmentioning

confidence: 99%

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

Kesim

Zhang

Trolier-McKinstry

et al. 2013

Journal of Applied Physics

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“…Such macroscopic inversion symmetry breaking and the associated novel physical properties have attracted widespread experimental and theoretical attention in the past decade. In contrast to single-component ferroelectrics, the degeneracy between the two polarization states in these materials is broken by a built-in electric field, which has been shown to result in self-poling, 1 shifted hysteresis loops, 2,3 enhanced susceptibilities, [4][5][6][7] and signatures of geometric frustration. 8 Such a built-in bias within the material is typically generated by an inhomogeneous strain through lattice engineering (via multicomponent superlattices) 9,10 or a global composition gradient.…”

Section: Introductionmentioning

confidence: 99%

Large built-in electric fields due to flexoelectricity in compositionally graded ferroelectric thin films

et al. 2013

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TitleLarge built-in electric fields due to flexoelectricity in compositionally graded ferroelectric thin films We investigate the origin of large built-in electric fields that have been reported in compositionally graded ferroelectric thin films using PbZr 1−x Ti x O 3 (0.2 < x < 0.8) as a model system. We show that the built-in electric fields that cause a voltage offset in the hysteresis loops are dependent on strain relaxation (through misfit dislocation formation) and the accompanying polarization distribution within the material. Using a GinzburgLandau-Devonshire phenomenological formalism that includes the effects of compositional gradients, mechanical strain relaxation, and flexoelectricity, we demonstrate that the flexoelectric coupling between the out-of-plane polarization and the gradient of the epitaxial strain throughout the thickness of the film, not other inhomogeneities (i.e., composition or polarization), is directly responsible for the observed voltage offsets. This work demonstrates the importance of flexoelectricity in influencing the properties of ferroelectric thin films and provides a powerful mechanism to control their properties.

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“…Their distinctive electric-field, thermal, and stress susceptibilities make such systems potentially important for a range of devices [2]. Compositionally graded ferroelectrics have been probed both experimentally [3,[5][6][7][8] and theoretically using Slater models [9], phenomenological Landau theory [10][11][12][13], transverse Ising models [14,15], and first-principles calculations [4] in an attempt to understand their internal crystal and polarization structure and the mechanisms underlying the manifestation of exotic properties. In this work, we focus on phenomenological approaches and thus narrow our discussion in this capacity.…”

Section: Introductionmentioning

confidence: 99%

Understanding order in compositionally graded ferroelectrics: Flexoelectricity, gradient, and depolarization field effects

Zhang

Damodaran

et al. 2014

Phys. Rev. B

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A nonlinear thermodynamic formalism based on Ginzburg-Landau-Devonshire theory is developed to describe the total free energy density in (001)-oriented, compositionally graded, and monodomain ferroelectric films including the relative contributions and importance of flexoelectric, gradient, and depolarization energy terms. The effects of these energies on the evolution of the spontaneous polarization, dielectric permittivity, and the pyroelectric coefficient as a function of position throughout the film thickness, temperature, and epitaxial strain state are explored. In general, the presence of a compositional gradient and the three energy terms tend to stabilize a polar, ferroelectric state even in compositions that should be paraelectric in the bulk. Flexoelectric effects produce large built-in fields which diminish the temperature dependence of the polarization and susceptibilities. Gradient energy terms, here used to describe short-scale correlation between dipoles, have minimal impact on the polarization and susceptibilities. Finally, depolarization energy significantly impacts the temperature and strain dependence, as well as the magnitude, of the susceptibilities. This approach provides guidance on how to more accurately model compositionally graded films and presents experimental approaches that could enable differentiation and determination of the constitutive coefficients of interest.

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Giant effective pyroelectric coefficients from graded ferroelectric devices

Cited by 119 publications

References 10 publications

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

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

Large built-in electric fields due to flexoelectricity in compositionally graded ferroelectric thin films

Understanding order in compositionally graded ferroelectrics: Flexoelectricity, gradient, and depolarization field effects

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