Effect of growth defects on microwave properties in epitaxial Ba0.5Sr0.5TiO3thin films grown on (001) MgO by pulsed laser deposition

Tse, Yau Yau; Suherman, P. M.; Jackson, Tim; Jones, I.P.

doi:10.1080/14786430802375642

Cited by 9 publications

(3 citation statements)

References 26 publications

(21 reference statements)

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“…1 have associated the improvement in the dielectric properties to the high structural quality of the as-deposited films while Tse et al . 8 have attributed the increase of 40% in the dielectric tunability to the reduction of 40% in the threading dislocation density due to the post annealing of epitaxial Ba 0.5 Sr 0.5 TiO 3 thin films grown on (001) MgO by pulsed laser deposition.…”

Section: Introductionmentioning

confidence: 99%

Real time in situ x-ray diffraction study of the crystalline structure modification of Ba0.5Sr0.5TiO3 during the post-annealing

Bauer

Rodrigues

Baumbach

2018

Sci Rep

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We report about an in situ study of crystalline structural changes during thermal treatment of a Ba0.5Sr0.5TiO3 (BSTO) film grown on MgO. The study covers the complete cycle of heating, annealing and cooling and reveals simultaneous phenomena of phase transitions and strain evolution, which have been characterized by in situ 2D reciprocal space mapping (2D-RSM) using high-resolution synchrotron x-ray diffraction in coplanar and grazing incidence geometries. In this way, temperature induced phase transformation from the BSTO2 to the BSTO1 phase has been monitored and the appearance of a further crystalline phase was detected. Moreover, for both BSTO phases, transitions between in-plane compressive and tensile states have been determined during thermal treatment. Furthermore, a contraction of the out-of-plane lattice components has been observed during the annealing phase while the in-plane lattice components remain leading to the change of the residual in-plane strain towards tensile state. The in situ 2D-RSM findings provide valuable and versatile insights into strain engineering and structure modification upon thermal treatment.

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Section: Introductionmentioning

confidence: 99%

Real time in situ x-ray diffraction study of the crystalline structure modification of Ba0.5Sr0.5TiO3 during the post-annealing

Bauer

Rodrigues

Baumbach

2018

Sci Rep

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“…Such mechanisms facilitate the nucleation of dislocations in oxide films, which assist the strain relaxation at T dep [68,69]. Note, edge dislocations, uniformly distributed along the entire BST-0.5/LAO interface, and both edge and threading dislocations in BST-0.5/MgO to relieve misfit stresses have been previously observed by high-resolution transmission electron microscopy [70,71]. To estimate the in-plane strains in epitaxial BST-0.5 on single crystal substrates, two assumptions are made, namely, (a) the coefficient of thermal expansions of film and substrate are constant, and (b) additional formation of dislocations during cooling from 720 • C to RT is minimal.…”

Section: Substrate-dependent In-plane Strain In Bst-05 Filmsmentioning

confidence: 69%

“…Apparently, strain fields surrounding the dislocations also enhance the depolarization fields and higher film thicknesses are required for polarization saturation [17]. Indeed, for a 350 nm PLD BST-0.5 film, it has been demonstrated that a reduction in dislocation density, by ex situ annealing in flowing oxygen at 1150 • C for 24 h, has resulted in an increase in permittivity from 870 (as-deposited) to 2000 (annealed) at 20 GHz [71].…”

Section: Factors Influencing Microwave Dielectric Responses Of Bst-05...mentioning

confidence: 99%

Analyses of Substrate-Dependent Broadband Microwave (1–40 GHz) Dielectric Properties of Pulsed Laser Deposited Ba0.5Sr0.5TiO3 Films

Dey

Sudheendran²,

Pavunny

et al. 2021

Crystals

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Ba0.5Sr0.5TiO3 (BST-0.5) thin films (600 nm) were deposited on single crystal MgO, SrTiO3 (STO), and LaAlO3 (LAO) substrates by pulsed laser deposition at an oxygen partial pressure of 80 mTorr and temperature of 720 °C. X-ray diffraction and in situ reflection high-energy electron diffraction routinely ascertained the epitaxial quality of the (100)-oriented nanocrystalline films. The broadband microwave (1–40 GHz) dielectric properties were measured using coplanar waveguide transmission line test structures. The out-of-plane relative permittivity exhibited strong substrate-dependent dielectric (relaxation) dispersions with their attendant peaks in loss tangent (tanδ), with the former dropping sharply from tens of thousands to ~1000 by 10 GHz. Although homogeneous in-plane strain , enhances with at lower frequencies, two crossover points at 8.6 GHz and 18 GHz eventually change the trend to: . The dispersions are qualitatively interpreted using (a) theoretically calculated (T)- phase diagram for single crystal and single domain BST-0.5 film, (b) theoretically predicted -dependent, anomaly that does not account for frequency dependence, and (c) literature reports on intrinsic and extrinsic microstructural effects, including defects-induced inhomogeneous strain and strain gradients. From the Vendik and Zubko model, the defect parameter metric, , was estimated to be 0.51 at 40 GHz for BST-0.5 film on STO.

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Nanoscale defects and microwave properties of (BaSr)TiO3 ferroelectric thin films

Jackson

Jones

2009

J Mater Sci

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Effect of growth defects on microwave properties in epitaxial Ba_0.5Sr_0.5TiO₃thin films grown on (001) MgO by pulsed laser deposition

Cited by 9 publications

References 26 publications

Real time in situ x-ray diffraction study of the crystalline structure modification of Ba0.5Sr0.5TiO3 during the post-annealing

Real time in situ x-ray diffraction study of the crystalline structure modification of Ba0.5Sr0.5TiO3 during the post-annealing

Analyses of Substrate-Dependent Broadband Microwave (1–40 GHz) Dielectric Properties of Pulsed Laser Deposited Ba0.5Sr0.5TiO3 Films

Nanoscale defects and microwave properties of (BaSr)TiO3 ferroelectric thin films

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