MOCVD precursor design issues. Recent advances in the chemistry and vapor pressure characteristics of Ba(hexafluoroacetylacetonate)2·polyether complexes

Marks, Tobin J.; Belot, John A.; Reedy, Charles J.; McNeely, Richard J.; Studebaker, D. B.; Neumayer, Deborah A.; Stern, Charlotte L.

doi:10.1016/s0925-8388(96)02680-1

Cited by 13 publications

(8 citation statements)

References 32 publications

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“…Metal complexes have been used extensively as metal sources for the material syntheses. − Many experimental and theoretical approaches to the selection (or design) of precursor metal complexes have been demonstrated. − The decomposition of precursor complexes is considered an important reaction determining the quality of products in the material syntheses. Therefore, the understanding of the complex stability is expected to be important for selection of suitable precursors.…”

Section: Introductionmentioning

confidence: 99%

Computational Method for Efficient Screening of Metal Precursors for Nanomaterial Syntheses

Orimoto

Toyota

Furuya

et al. 2009

Ind. Eng. Chem. Res.

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A density functional theory (DFT) based method is proposed for efficient screening of metal precursors for nanomaterial syntheses. For this study, we examined the effectiveness of our DFT approach for predicting bulk properties of precursor metal complexes, which is a key of our method. The DFT calculations were applied for a series of copper(II) β-diketonate complexes to estimate values related to complex stabilities such as complex formation energies ΔE total complex, total energy changes for two-electron reduction ΔE total reduction, and so on. The value of ΔE total complex was compared to the stability constant β2 collected from the relevant literature; ΔE total reduction was compared with reduction potentials measured using cyclic voltammetry. Results obtained from these comparisons revealed that simple DFT calculations predicted the trend of the complex stabilities that were determined experimentally as a bulk property. Our method can predict precursor properties and can greatly contribute to efficient precursor selection for nanomaterial synthesis.

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Section: Introductionmentioning

confidence: 99%

Computational Method for Efficient Screening of Metal Precursors for Nanomaterial Syntheses

Orimoto

Toyota

Furuya

et al. 2009

Ind. Eng. Chem. Res.

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“…However, the success of an MOCVD process depends critically on the availability of volatile, thermally stable precursors which exhibit constant vapor pressure and the capacity to selectively form the desired phase at the substrate surface. Low-melting precursors are preferred because solid compounds can be handled with ease at room temperature, while the liquid form at reservoir operating temperatures affords constant surface area for stable vapor delivery to the reactor. − …”

Section: Introductionmentioning

confidence: 99%

“…Thus far, many growth techniques including MBE, , pulsed laser deposition, , sputtering, − and electron beam evaporation , have been utilized for CeO 2 film growth. However, as noted above, molecule-based metal−organic chemical vapor deposition (MOCVD) techniques offer many attractive features such as conformal coverage, ability to coat complex shapes, simplified apparatus, and lower growth temperatures for thin film growth and device fabrication. − Nevertheless, MOCVD has not been fully optimized for CeO 2 deposition. Although low-temperature film deposition is requisite for multilayer device fabrication, all CeO 2 MOCVD processes reported prior to this contribution have required very high growth temperatures (680−800 °C). ,,, Efforts have been made to improve these CeO 2 growth parameters by using special reactors and/or other methods; , however, high deposition temperatures are still required.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Volatile, Fluorine-Free β-Ketoiminate Lanthanide MOCVD Precursors and Their Implementation in Low-Temperature Growth of Epitaxial CeO₂ Buffer Layers for Superconducting Electronics

et al. 2002

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A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric Ce, Nd, Gd, and Er complexes are coordinatively saturated by a versatile, multidentate ether-functionalized beta-ketoiminato ligand series, the melting point and volatility characteristics of which can be tuned by altering the alkyl substituents on the keto, imino, and ether sites of the ligand. Direct comparison with conventional lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD. Epitaxial CeO(2) buffer layer films can be grown on (001) YSZ substrates by MOCVD at significantly lower temperatures (450-650 degrees C) than previously possible by using one of the newly developed cerium beta-ketoiminate precursors. Films deposited at 540 degrees C have good out-of-plane (Deltaomega = 0.85 degrees ) and in-plane (Deltaphi = 1.65 degrees ) alignment and smooth surfaces (rms roughness approximately 4.3 A). The film growth rate decreases and the films tend to be smoother as the deposition temperature is increased. High-quality yttrium barium copper oxide (YBCO) films grown on these CeO(2) buffer layers by pulsed organometallic molecular beam epitaxy exhibit very good electrical transport properties (T(c) = 86.5 K, J(c) = 1.08 x 10(6) A/cm(2) at 77.4 K).

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“…In spite of these issues, there has been progress with group 2 ALD and CVD precursors. A successful class of CVD precursors for strontium and barium contains fluorinated β-diketonate and neutral polydentate ether ligands . These complexes undergo vapor transport between 120 and 160 °C at reduced pressures .…”

Section: Introductionmentioning

confidence: 99%

“…A successful class of CVD precursors for strontium and barium contains fluorinated β-diketonate and neutral polydentate ether ligands . These complexes undergo vapor transport between 120 and 160 °C at reduced pressures . Fluorine contamination in the thin films is a potential drawback, and thus recent effort has focused on the development of halogen-free precursors.…”

Section: Introductionmentioning

confidence: 99%

Highly Distorted κ³-N,N,H Bonding of Bis(3,5-di-tert-butylpyrazolyl)borate Ligands to the Heavier Group 2 Elements

Saly

Winter

2010

Organometallics

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Treatment of MI 2 (M = Ca, Sr, Ba) with two equivalents of thallium bis(3,5-di-tert-butylpyrazolyl)borate (TlBp tBu2 ) in tetrahydrofuran at ambient temperature afforded CaBp tBu2 2 (67%), SrBp tBu2 2 (79%), and BaBp tBu2 2 (THF) (63%). Sublimation of BaBp tBu2 2 (THF) at 205°C/0.05 Torr afforded BaBp tBu2 2 (37%) along with loss of tetrahydrofuran. Crystal structure determinations of SrBp tBu2 2 , BaBp tBu2 2 (THF), and BaBp tBu2 2 revealed monomeric structures containing highly distorted κ 3 -N,N,H-Bp tBu2 ligands. The M-N-N-B torsion angles in SrBp tBu2 2 , BaBp tBu2 2 (THF), and BaBp tBu2 2 range from 20.00(8)°to 60.90(1)°, which indicate significant deformation of the 3,5-ditert-butylpyrazolyl groups in order to avoid intraligand and interligand tert-butyl group steric repulsions. BH 2 (tBu 2 pz)(tBu 2 pzH) was prepared in 78% yield by treatment of Li(Bp tBu2 )(THF) with pivalic acid, and its X-ray crystal structure was determined. To assess the viability of MBp tBu2 2 (M = Ca, Sr, Ba) as potential thin-film growth precursors, solid-state decomposition studies, thermogravimetric analyses, and preparative sublimations were performed. SrBp tBu2 2 is the most thermally stable among the series, with a solid-state decomposition temperature of 325°C, a sublimation temperature of 190°C/0.05 Torr, and a nonvolatile residue of 3.6% in a preparative sublimation. The TGA traces of CaBp tBu2 2 and SrBp tBu2 2 show weight loss regimes from 150 to 325°C, with final percent residues of 20% and 25%, respectively. Several of the new complexes exhibit much higher thermal stability than existing group 2 chemical vapor deposition precursors and, thus, may serve as film growth precursors.

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MOCVD precursor design issues. Recent advances in the chemistry and vapor pressure characteristics of Ba(hexafluoroacetylacetonate)2·polyether complexes

Cited by 13 publications

References 32 publications

Computational Method for Efficient Screening of Metal Precursors for Nanomaterial Syntheses

Computational Method for Efficient Screening of Metal Precursors for Nanomaterial Syntheses

Synthesis and Characterization of Volatile, Fluorine-Free β-Ketoiminate Lanthanide MOCVD Precursors and Their Implementation in Low-Temperature Growth of Epitaxial CeO₂ Buffer Layers for Superconducting Electronics

Highly Distorted κ³-N,N,H Bonding of Bis(3,5-di-tert-butylpyrazolyl)borate Ligands to the Heavier Group 2 Elements

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MOCVD precursor design issues. Recent advances in the chemistry and vapor pressure characteristics of Ba(hexafluoroacetylacetonate)2·polyether complexes

Cited by 13 publications

References 32 publications

Computational Method for Efficient Screening of Metal Precursors for Nanomaterial Syntheses

Computational Method for Efficient Screening of Metal Precursors for Nanomaterial Syntheses

Synthesis and Characterization of Volatile, Fluorine-Free β-Ketoiminate Lanthanide MOCVD Precursors and Their Implementation in Low-Temperature Growth of Epitaxial CeO2 Buffer Layers for Superconducting Electronics

Highly Distorted κ3-N,N,H Bonding of Bis(3,5-di-tert-butylpyrazolyl)borate Ligands to the Heavier Group 2 Elements

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Product

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Synthesis and Characterization of Volatile, Fluorine-Free β-Ketoiminate Lanthanide MOCVD Precursors and Their Implementation in Low-Temperature Growth of Epitaxial CeO₂ Buffer Layers for Superconducting Electronics

Highly Distorted κ³-N,N,H Bonding of Bis(3,5-di-tert-butylpyrazolyl)borate Ligands to the Heavier Group 2 Elements