Chemically Homogeneous Complex Oxide Thin Films Via Improved Substrate Metallization

Shelton, Christopher T.; Kotula, Paul G.; Brennecka, Geoff L.; Lam, Peter G.; Meyer, Kelsey; Maria, Jon Paul; Gibbons, Brady J.; Ihlefeld, Jon F.

doi:10.1002/adfm.201103077

Cited by 56 publications

(68 citation statements)

References 32 publications

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“…30 Each BCZT seed layer was heat treated at 700 C for 5 min in this work, and thermal Ti gradients through the lms and are responsible for the observed changes in lm dielectric performance. 31 The dielectric constant has strong eld dependence, where typically the dielectric constant decreases with increasing eld. At the bias electric eld of 400 kV cm À1 , the dielectric constant 3 (v) of 900 render to tunability of 28.5%, dened as [3 (0) -3 (v) ]/3 (0) Â 100% for the lm with 10 nm-thick seed layer.…”

Section: Resultsmentioning

confidence: 99%

Microstructure and electric properties of BCZT thin films with seed layers

et al. 2017

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Lead free Ba 0.99 Ca 0.01 Ti 0.98 Zr 0.02 O 3 (BCZT) thin films with seed layers were prepared by using sol-gel processing technique. The seed layers, ranging from 10 nm to 40 nm, were introduced between the BCZT films and the Pt(111)/Ti/SiO 2 /Si substrates. The effects of seed layer thickness on the structure and dielectric properties of the thin films were investigated. With the increase of seed layer thickness, the grain size of the BCZT thin films increases from about 100 nm to 300 nm, accordingly, the dielectric constants decrease at lower frequency. The highest dielectric tunability is 34.5% for the films with a 20 nm-thick seed layer. Improved effective piezoelectric coefficients (d 33 ) were observed in the BCZT thin films. The maximum d 33 value of BCZT thin films with a 30 nm-thick seed layer is approximately 70 pm V À1, which is comparable to that of polycrystalline PZT thin films. The seed layer thickness dependence of the electric properties is attributed to the dipole polarization. This demonstrated the possibility to control the microstructure and improve properties of BCZT thin films, which could be exploited for functional devices that demand high quality.

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Section: Resultsmentioning

confidence: 99%

Microstructure and electric properties of BCZT thin films with seed layers

et al. 2017

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“…[ 9 ] Diffusion and chemical reactions have also been observed, often related to the diffusion of metallic species such as Pb and Ti. Suffi cient diffusion can result in the observation of intermetallic compounds such as Pt 3 Pb and Pt 3 Ti. [10][11][12][13][14][15][16][17][18] However, several questions remain unanswered including the interplay of these various compounds and phenomena, as well as their role in fi lm crystallization and observed ferroelectric properties.…”

Section: Introductionmentioning

confidence: 99%

“…[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 such as perovskite PZT and PbTiO 3 , much has been learned about fi lm-substrate interactions during the heating treatment. For example, PbO and TiO 2 at the interface with the bottom electrode have been shown to induce seeding of preferred orientation of the ferroelectric fi lm during crystallization.…”

Section: Introductionmentioning

confidence: 99%

“…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.…”

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

Jones

LeBeau

Nikkel

et al. 2015

Adv Materials Inter

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(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.

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“…BaTiO 3 thin films were prepared via chemical solution deposition utilizing a varying final anneal temperature to modify the final grain size [145]. A chelate chemistry comprised of barium acetate, titanium isopropoxide, acetylacetonate, propionic acid, and methanol was used and is described in more detail in prior work [272]. Cation precursors were assayed prior to batching to ensure a stoichiometric composition.…”

Section: Batio 3 Film Fabrication and Characterizationmentioning

confidence: 99%

Understanding Phonon Interactions with Defects in Functional Oxide Materials

Donovan¹

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Understanding of nano-scale thermal transport has enabled significant advances in a wide variety of fields including microelectronics, alternative energy, optics, and many more [1][2][3][4]. Utilized in many of these applications are a class of materials known as functional oxides. These materials are oxygen compounds with specific functional properties of interest (e.g., dielectrics [5][6][7][8], piezoelectrics [9][10][11], photovoltaics [12][13][14], thermoelectrics [15][16][17][18][19]). Often it is the defects in these materials that enable functionality and, depending on the processing and operating conditions, the concentration and types of defects that are present in these materials can vary widely [20]. In this dissertation, I aim to identify the role that defects play in functional oxide materials with respect to thermal transport.The major thermal carriers in most functional oxide crystals are collective lattice vibrations, or phonons [21]. Phonon-dominated thermal conductivity is dictated by the scattering of these thermal carriers with a variety of other components or the material system, including defects in the crystal [22,23]. I concentrate on three types of defects that are common in functional oxides: boundaries, extrinsic point defects, and intrinsic point defects.Boundaries such as film boundaries and grain boundaries with nano-scale dimensions can be detrimental to the thermal conductivity of a material. As the length of the uninterrupted crystal reduces to the phonon mean free paths in the crystal, phonons will scatter readily off of nano-scale boundaries and will not be able to propagate as they would in a bulk environment. This becomes particularly relevant in technologies such as the microelectronics industry, where device size scales are well below common phonon mean free paths in the constituent materials. To study this, I turn to one of the more common functional oxides used in the microelectronics industry, BaTiO 3 .I study the effects of nano-scale grains on thin films of BaTiO 3 grown via chemical solution deposition. The films studied are 150 nm and range in grain size from 36 nm -63 nm. I show that the thermal conductivity of these nano-grained films scales with the grain size and film thickness and demonstrate agreement of this trend with analytical models. This result demonstrates that despite a complex crystal structure, there is a mean free path spectrum of phonons in BaTiO 3 that significantly exceeds the dimensions of the grains and film (contrary to the common "gray" mean 2 free path assumption seen in literature).To address the role of extrinsic point defects, or dopants, on the thermal conductivity of functional oxides, I study the effects of dysprosium doping in thin films of cadmium oxide deposited by molecular beam epitaxy. In this experiment, the addition of Dy dopants in CdO actually increases the thermal conductivity initially, owing to a reduction in the equilibrium concentration of oxygen vacancies (a type of defect that is intrinsic to all oxides). The de...

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Chemically Homogeneous Complex Oxide Thin Films Via Improved Substrate Metallization

Cited by 56 publications

References 32 publications

Microstructure and electric properties of BCZT thin films with seed layers

Microstructure and electric properties of BCZT thin films with seed layers

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

Understanding Phonon Interactions with Defects in Functional Oxide Materials

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