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

Abstract

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.

Heteroepitaxial Hexagonal (00.1) CuFeO2 Thin Film Grown on Cubic (001) SrTiO3 Substrate Through Translational and Rotational Domain Matching

“…Figure 1a shows a representative out-of-plane X-ray diffraction (XRD) pattern of the CuFeO 2 thin films. The 2θ-ω scans were aligned and calibrated using the (002) SrTiO 3 reflection at 46.470 (a ¼ 3.905 Å). The film exhibits a series of peaks assigned to the (00.3), (00.6), (00.9), and (00.12) planes of the hexagonal delafossite structure of CuFeO 2 .…”

“…[44] In some cases, a structurally modified transition layer has been reported to be formed at the interface to facilitate the heteroepitaxial growth. [45,46] Recently, domain matching epitaxy was observed for orthorhombic (111) Hf 0.5 Zr 0.5 O 2 (HZO) thin films grown on cubic (001) La 2/3 Sr 1/3 MnO 3 (LSMO) epitaxial layer through the introduction of arrays of interface dislocations with short periodic spacing. [47] In this unique case, the crystal planes of the film and substrate show an apparent symmetry dissimilarity, whereas the lattice mismatches along two in-plane matching orientations of HZO [211]//LSMO [110] and HZO [022]//LSMO [110] are calculated to be about 10% and 58%, respectively.…”

Polaron formation in Bi-deficient BaBiO3

“…Reports on BBO thin films are scarce [22][23][24][25][26][27][28][29][30][31]. Most papers report on the growth and properties of BBO on SrTiO 3 (STO) substrates [22,23,25,[28][29][30][31], with both materials presenting a rather large lattice mismatch of ≈12%.…”

“…Reports on BBO thin films are scarce [22][23][24][25][26][27][28][29][30][31]. Most papers report on the growth and properties of BBO on SrTiO 3 (STO) substrates [22,23,25,[28][29][30][31], with both materials presenting a rather large lattice mismatch of ≈12%. It was shown that this misfit is accommodated through the formation of an ultrathin interfacial δ-Bi 2 O 3 layer with a fluorite structure, which forms a coherent interface with the substrate and a semi-coherent interface with BBO [28,31].…”

“…Most papers report on the growth and properties of BBO on SrTiO 3 (STO) substrates [22,23,25,[28][29][30][31], with both materials presenting a rather large lattice mismatch of ≈12%. It was shown that this misfit is accommodated through the formation of an ultrathin interfacial δ-Bi 2 O 3 layer with a fluorite structure, which forms a coherent interface with the substrate and a semi-coherent interface with BBO [28,31]. Recent reports indicate that the electronic structure of BBO on STO is thickness dependent and is affected by chemical and structural effects imposed by the substrate/film interface [29,32].…”