Influence of Sr deficiency on structural and electrical properties of SrTiO3 thin films grown by metal–organic vapor phase epitaxy

Baki, Aykut; Stöver, Julian; Schulz, Tobias; Markurt, Toni; Amari, Houari; Richter, Carsten; Martin, Jens; Irmscher, K.; Albrecht, M.; Schwarzkopf, Jutta

doi:10.1038/s41598-021-87007-2

Cited by 11 publications

(13 citation statements)

References 55 publications

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“…No contrast fluctuations are observed within the film indicating homogeneous and coherent film growth. This is verified by high-resolution transmission electron microscopy (HRTEM) measurements, presented in Figure 2b, which also display an atomically sharp SrSnO 3 /NdScO 3 interface seen along [1][2][3][4][5][6][7][8][9][10] direction and no extended defects in the SrSnO 3 film. On the other side, a strong dark contrast occurs at the interface between the undoped BaSnO 3 and SrSnO 3 layers and a large amount of threading dislocations is visible in the BaSnO 3 film (Figure 2a), which lead to the formation of strong strain fields at the BaSnO 3 /SrSnO 3 interface.…”

Section: Introductionsupporting

confidence: 62%

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Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Pfützenreuter

Kim

Cho

et al. 2022

Adv Materials Inter

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temperature mobility of 320 cm 2 V −1 s −1 at a carrier density of 8.0 × 10 19 cm −3 in a bulk single crystal. [8] Furthermore, BaSnO 3 is a transparent wide bandgap semiconductor with a bandgap of 3.1 eV, which makes it suitable for high power applications like field effect transistors (FET). [9] To exploit the full potential of a FET, a 2D electron gas (2DEG) with high carrier density and mobility is highly desirable. The formation of a 2DEG at the LaInO 3 /BaSnO 3 interface was found and studied experimentally by Kim et al. in 2016 and thereafter [10,11] and has been theoretically investigated using several models. [12][13][14] Analysis of the Seebeck coefficient as well as Poisson-Schrödinger simulations suggested a thickness of ≈1 nm for the 2DEG. [14] Recently, another similar polar interface, namely LaScO 3 /BaSnO 3 , has been investigated. [15,16] In this paper we report on the epitaxial growth of LaInO 3 / BaSnO 3 heterointerfaces using a SrSnO 3 buffer layer on NdScO 3 substrates. We provide clear evidence for the enhancement of the conductance at the LaInO 3 /BaSnO 3 interface for a compensated BaSnO 3 :La channel layer. More importantly, we report on the length scale of the charge accumulation at the heterointerface and with that further support the finding of a 2DEG at the heterointerface. We also present the low temperature electrical properties of the heterointerface, displaying reduced carrier density and increased mobility Results and Discussion Structural Properties of the HeterostructureA high-resolution X-ray diffraction (HRXRD) 2θ−ω scan around the (220) NdScO 3 Bragg reflection shows three contributions, which can be attributed to the BaSnO 3 and SrSnO 3 films as well as to the NdScO 3 substrate (see Figure 1a). The SrSnO 3 film peak appears at 44.7°, which corresponds to a vertical lattice parameter of 4.056 Å. This coincides with the expected vertical lattice parameter of a fully compressively strained film, which is obtained from linear elasticity theory under the assumption of a Poisson ratio of ν = 0.23 and a lattice mismatch of 0.5% in [1-10] direction and 0.8% in [001] direction of the NdScO 3 substrate. [17] An reciprocal space mappings (RSM) measurement (Figure 1c) in the vicinity of the asymmetric (332) NdScO 3 substrate reflection exhibits the SrSnO 3 contribution directly belowThe properties of the conductance at the LaInO 3 /BaSnO 3 heterointerface are reported. The heterointerface is formed by covering the semi-insulating BaSnO 3 :La thin films with 10 nm LaInO 3 films, which are all epitaxially grown on NdScO 3 substrates. Structural properties of BaSnO 3 thin films are investigated by means of X-ray diffraction and transmission electron microscopy and exhibit a threading dislocation density of 6 × 10 10 cm −2 . Via capacitance-voltage (C-V) measurements, clear evidence is present for the accumulation of electrons at the interface within 2.5 nm in the BaSnO 3 layer, confirming the formation of a 2D electron gas (2DEG). Additionally, temperature dependent Hall effect measurem...

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Section: Introductionsupporting

confidence: 62%

“…depending on their chemical composition and crystal structure. [1][2][3][4][5] In addition, electrical properties of perovskites can easily be manipulated by doping and/or incorporation of lattice strain, which enables their use in various applications. [6,7] However, the main challenge has been their high carrier density and low mobility.…”

Section: Introductionmentioning

confidence: 99%

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Pfützenreuter

Kim

Cho

et al. 2022

Adv Materials Inter

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“…Our work evidences the lack of semiconductor-like properties in the absence of such processing. Concurrently, in the last years, it has been found that structural or compositional defects, other than oxygen vacancies/substitutions, can drive the electronic properties of STO towards semiconductor state 49 – 54 . We believe that during high-temperature processes, such defects can unintentionally form and lead to the increased optical absorption and electrical conductivity.…”

Section: Resultsmentioning

confidence: 98%

The electronic properties of SrTiO3-δ with oxygen vacancies or substitutions

Rusevich

Tyunina

Kotomin

et al. 2021

Sci Rep

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The electronic properties, including bandgap and conductivity, are critical for nearly all applications of multifunctional perovskite oxide ferroelectrics. Here we analysed possibility to induce semiconductor behaviour in these materials, which are basically insulators, by replacement of several percent of oxygen atoms with nitrogen, hydrogen, or vacancies. We explored this approach for one of the best studied members of the large family of ABO3 perovskite ferroelectrics — strontium titanate (SrTiO3). The atomic and electronic structure of defects were theoretically investigated using the large-scale first-principles calculations for both bulk crystal and thin films. The results of calculations were experimentally verified by studies of the optical properties at photon energies from 25 meV to 8.8 eV for in-situ prepared thin films. It was demonstrated that substitutions and vacancies prefer locations at surfaces or phase boundaries over those inside crystallites. At the same time, local states in the bandgap can be produced by vacancies located both inside the crystals and at the surface, but by nitrogen substitution only inside crystals. Wide-bandgap insulator phases were evidenced for all defects. Compared to pure SrTiO3 films, bandgap widening due to defects was theoretically predicted and experimentally detected.

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“…As a rule, the novel functional materials are very often created on the platform of complex oxides 1 – 3 . The main advantage of oxides is their chemical stability during operation of the material in an air atmosphere 4 .…”

Section: Introductionmentioning

confidence: 99%

Features of structure, magnetic state and electrodynamic performance of SrFe12−xInxO19

Турченко

Труханов

Костишин

et al. 2021

Sci Rep

119

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Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.

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Influence of Sr deficiency on structural and electrical properties of SrTiO3 thin films grown by metal–organic vapor phase epitaxy

Cited by 11 publications

References 55 publications

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

The electronic properties of SrTiO3-δ with oxygen vacancies or substitutions

Features of structure, magnetic state and electrodynamic performance of SrFe12−xInxO19

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Influence of Sr deficiency on structural and electrical properties of SrTiO3 thin films grown by metal–organic vapor phase epitaxy

Cited by 11 publications

References 55 publications

Confinement of Electrons at the LaInO3/BaSnO3 Heterointerface

Confinement of Electrons at the LaInO3/BaSnO3 Heterointerface

The electronic properties of SrTiO3-δ with oxygen vacancies or substitutions

Features of structure, magnetic state and electrodynamic performance of SrFe12−xInxO19

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Product

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Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface