Double-layer buffer template to grow commensurate epitaxial BaBiO3 thin films

Lee, Han Gyeol; Kim, Yoonkoo; Hwang, Sang Woon; Kim, Gideok; Kang, Thomas H.‐K.; Kim, Minu; Kim, Miyoung; Noh, Tae Won

doi:10.1063/1.4972133

Cited by 15 publications

(10 citation statements)

References 30 publications

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“…In contrast to the studies on the synthesis of BBO single crystals, reports on epitaxial growth of BBO thin films are limited. It has been shown that, aside from the growth on MgO substrates (lattice mismatch of ≈1.4%), smooth and well‐ordered BBO thin films can be deposited on SrTiO 3 substrates (lattice mismatch of ≈12%) through domain matching epitaxy even without the use of buffer layers such as BaO and BaCeO 3 /BaZrO 3 . BBO films can be further used as buffer layers for the stabilization of the energetically unfavorable, but electronically nontrivial perovskite phase in the YBiO system .…”

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confidence: 99%

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO₃ Thin Films Grown on SrTiO₃ Substrates

Jin

Zapf

Stübinger

et al. 2020

Physica Rapid Research Ltrs

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The electronic structures of BaBiO3 (BBO) thin films grown on SrTiO3 substrates are found to be thickness dependent. The origin of this behavior remains under debate and has been suggested to be attributed to the structural and compositional modifications at the BBO/SrTiO3 interface during the first stage of film growth. Though a wetting layer with thickness of ≈1 nm has been experimentally identified at the interface, details on the microstructures of such a layer and their effect on the subsequent film growth are lacking so far, particularly at the atomic scale. Herein, atomic‐resolution scanning transmission electron microscopy is used to study the interface structure of a 30 nm‐thick BBO film grown on an Nb‐doped SrTiO3 (STO) substrate through domain matching epitaxy. An interfacial δ‐Bi2O3 (BO)‐like phase with fluorite structure is identified, showing a layer‐by‐layer spacing of ≈3.2 Å along the growth direction. The orientation relationship between the BO‐like phase and surrounding perovskites (P) is found to be <001>BO||<001>P and <110>BO||<100>P. The presence of the BO‐like phase results in two types of interfaces, i.e., a coherent BO/STO and a semicoherent BBO/BO interface. Thickness variations are observed in the BO‐like layer, resulting in the formation of antiphase domains in the BBO films.

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confidence: 99%

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO₃ Thin Films Grown on SrTiO₃ Substrates

Jin

Zapf

Stübinger

et al. 2020

Physica Rapid Research Ltrs

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“…To realize the energetically unfavourable perovskite phase, the use of a buffer layer is investigated. In literature buffer layers are often used to con-trol the in-plane strain [13,14], quality [15,16] and crystal orientation [17] of the film deposited on top. BaBiO 3 (BBO) is suggested as suitable buffer layer material, since it has a lattice constant (a=4.35 Å [18]) comparable to the predicted perovskite YBO and it is stable in the perovskite phase.…”

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confidence: 99%

Stabilization of the Perovskite Phase in the Y–Bi–O System By Using a BaBiO₃ Buffer Layer

Bouwmeester

Hond

Gauquelin³

et al. 2019

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A topological insulating phase has theoretically been predicted for the thermodynamically unstable perovskite phase of YBiO 3 . Here, it is shown that the crystal structure of the Y-Bi-O system can be controlled by using a BaBiO 3 buffer layer. The BaBiO 3 film overcomes the large lattice mismatch of 12% with the SrTiO 3 substrate by forming a rocksalt structure in between the two perovskite structures. Depositing an YBiO 3 film directly on a SrTiO 3 substrate gives a fluorite structure. However, when the Y-Bi-O system is deposited on top of the buffer layer with the correct crystal phase and comparable lattice constant, a single oriented perovskite structure with the expected lattice constants is observed.Topological materials are at the focus of a relatively young field in material science, aiming to find both new topological materials as well as discovering novel applications for this new class of matter. The most prominent phenomena that emerge in topological materials include a chiral spin structure and topologically protected surface states. [1,2] The spin-momentum locking makes topological matter interesting for spintronic applications [1,3,4] and possibly quantum computation. [5] Therefore, global research is conducted towards further developing known topological materials and trying to find new compounds that have a non-trivial topology in their band structure.So far, only a handful of materials have been identified as topological insulators (TIs). Within a year after the theoretical prediction of Bernevig et al., [1] König et al. [3] observed the quantum spin Hall state in CdTe/HgTe/CdTe quantum wells À the first system known with a non-trivial band structure. Bi 1-x Sb x was the first three-dimensional TI that was experimentally observed, [6] followed by Bi 2 Se 3 , [7] and Bi 2 Te 3 . [4] The relatively heavy bismuth gives rise to strong spin-orbit coupling (SOC) effects, which in turn results in a band inversion at an odd

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“…K). A number of reports on the growth of undoped or hole-doped BBO films by molecular beam epitaxy (MBE) and pulsed laser deposition have recently appeared [9,10,16,[24][25][26][27][28][29]. One challenge is to find perovskite substrates to match BBOs large pseudocubic lattice parameter ∼4.35 Å. SBO has a smaller pseudocubic lattice parameter ∼4.25 Å resulting in a reasonable lattice match to some large lattice-parameter perovskite substrates such as BaSnO 3 (∼4.12 Å) and LaLuO 3 (∼4.18 Å).…”

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Epitaxial growth of perovskite SrBiO3 film on SrTiO3 by oxide molecular beam epitaxy

Davidson

Sutarto

et al. 2019

Phys. Rev. Materials

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Hole-doped perovskite bismuthates such as Ba1−xKxBiO3 and Sr1−xKxBiO3 are well-known bismuth-based oxide high-transition-temperature superconductors. Reported thin bismuthate films show relatively low quality, likely due to their large lattice mismatch with the substrate and a low sticking coefficient of Bi at high temperatures. Here, we report the successful epitaxial thin film growth of the parent compound strontium bismuthate SrBiO3 on SrO-terminated SrTiO3 (001) substrates by molecular beam epitaxy. Two different growth methods, high-temperature co-deposition or recrystallization cycles of low-temperature deposition plus high-temperature annealing, are developed to improve the epitaxial growth. SrBiO3 has a pseudocubic lattice constant ∼4.25Å, an ∼8.8% lattice mismatch on SrTiO3 substrate, leading to a large strain in the first few unit cells. Films thicker than 6 unit cells prepared by both methods are fully relaxed to bulk lattice constant and have similar quality. Compared to high-temperature co-deposition, the recrystallization method can produce higher quality 1-6 unit cell films that are coherently or partially strained. Photoemission experiments reveal the bonding and antibonding states close to the Fermi level due to Bi and O hybridization, in good agreement with density functional theory calculations. This work provides general guidance to the synthesis of high-quality perovskite bismuthate films.Hole-doped perovskite bismuthates Ba 1−x K x BiO 3 (x = 0.4) and Sr 1−x K x BiO 3 (x = 0.6) become superconducting below ∼30 K and ∼12 K, respectively [1,2]. Their parent compounds BaBiO 3 (BBO) and SrBiO 3 (SBO) have drawn intense interest [3][4][5][6][7][8][9][10][11][12][13][14][15][16] owing to the hightemperature superconductivity and also because of their indirect bandgap semiconductor nature rather than metals as would be expected from the half-filled Bi 6s band assuming the formal 4+ valence of Bi. The most common explanation of the nonmetallic behavior invokes the concept of charge disproportionation of Bi 4+ into the more stable and closed-shell atomic configurations of Bi 3+ (6s 2 ) and Bi 5+ (6s 0 ) [3,4,17]. This would inevitably result in a long Bi 3+ -O and a short Bi 5+ -O bond lengths ordered in the simplest conceivable structure with bond length alternation along the three crystallographic axes. Such bond disproportionation is observed in neutron and x-ray diffraction (XRD) [4,11] and in the resulting band structure [6,8]. However, x-ray photoemission spectroscopy (XPS) and density functional theory (DFT) calculations show that the charge difference between the two inequivalent Bi sites is trivial, at most a few tenths of one electron [8,10,[18][19][20][21]. By DFT calculation, Foyevtsova et al. recently demonstrates that the bands straddling the Fermi level are in fact strongly hybridized Bi 6s with O 2p molecular orbitals with A 1g symmetry and contain more O 2p character than Bi 6s character, resulting in the bonding states at ∼10 eV below the Fermi energy and the unoccupied antibonding ...

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Double-layer buffer template to grow commensurate epitaxial BaBiO3 thin films

Cited by 15 publications

References 30 publications

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO₃ Thin Films Grown on SrTiO₃ Substrates

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO₃ Thin Films Grown on SrTiO₃ Substrates

Stabilization of the Perovskite Phase in the Y–Bi–O System By Using a BaBiO₃ Buffer Layer

Epitaxial growth of perovskite SrBiO3 film on SrTiO3 by oxide molecular beam epitaxy

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Double-layer buffer template to grow commensurate epitaxial BaBiO3 thin films

Cited by 15 publications

References 30 publications

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO3 Thin Films Grown on SrTiO3 Substrates

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO3 Thin Films Grown on SrTiO3 Substrates

Stabilization of the Perovskite Phase in the Y–Bi–O System By Using a BaBiO3 Buffer Layer

Epitaxial growth of perovskite SrBiO3 film on SrTiO3 by oxide molecular beam epitaxy

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Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO₃ Thin Films Grown on SrTiO₃ Substrates

Atomic‐Scale Interface Structure in Domain Matching Epitaxial BaBiO₃ Thin Films Grown on SrTiO₃ Substrates

Stabilization of the Perovskite Phase in the Y–Bi–O System By Using a BaBiO₃ Buffer Layer