Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO<sub>3</sub> Thin‐Films Grown by Pulsed Laser Deposition

Bourlier, Yoan; Frégnaux, Mathieu; Bérini, Bruno; Fouchet, Arnaud; Dumont, Y.; Aureau, Damien

doi:10.1002/cnma.201900017

Cited by 15 publications

(29 citation statements)

References 64 publications

(136 reference statements)

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“…Alternatively, this may imply that the excess cations precipitate to form additional phases, which are disperse enough not to affect electron transport. Precipitates of foreign phases have been observed and analyzed by others in off‐stoichiometric films . While we were unable to observe such defects in our off‐stoichiometric films, in such proximity to 1:1 stoichiometry they might have a low volume fraction, below the detection of XRD.…”

Section: Transport Properties Of the Sample With The Highest Rrr Valumentioning

confidence: 64%

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Scalable Synthesis of the Transparent Conductive Oxide SrVO₃

Shoham

Baskin

Han

et al. 2019

Adv Elect Materials

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as a TCO. [1-3] This material is superior in conductivity to ITO, [1] and it is composed of abundant elements. In addition to its potential as a TCO, SVO constitutes the metallic endmember of several Mott-insulating systems such as La 1−x Sr x VO 3. [4-6] These systems attract interest both for their fundamental physics [7] and their potential for novel types of Mott-electronics. [8,9] It is therefore highly desirable to synthesize high quality films of this material, in order to unlock its full potential as TCO and to allow access to its interesting fundamental physics without the masking of high defect concentrations. To date, the highest quality SVO films have been demonstrated via hybrid molecular beam epitaxy (hMBE), where vanadium is supplied by a metal-organic precursor and strontium by a conventional thermal source. [10-12] In hMBE, by carefully calibrating the growth parameters, a self-limiting growth window can be obtained, [11,13-17] which provides the ultimate route for precise stoichiometry. [18] The lattice constant of epitaxial oxides provides a sensitive probe of their order and stoichiometry. [19] In addition, for many conductive oxides the residual resistivity ratio, RRR, is the most accurate probe, [20] since its sensitivity to defects far exceeds that of most structural and chemical analyses. RRR is the ratio between the room temperature and low temperature (2-5 K) resistivity. Based on Matthiessen's rule, RRR gauges the relative scattering by lattice defects versus the phonon scattering, and high values attest to the quality of the crystal structure and accuracy of the stoichiometry. The hMBE examples above have consistently reported RRR values exceeding 200, demonstrating the unrivaled accuracy of properly calibrated hMBE. Recently, significant efforts have been applied to understand and optimize the pulsed laser deposition (PLD) and growth kinetics of SVO, [21] with a record RRR value of 11.5. [3] While hMBE and PLD can be used to grow epitaxial oxides on conventional semiconductors, [22-25] an insulating interfacial layer forms at the contact with the semiconductor, preventing efficient charge collection from the substrate. Conventional molecular beam epitaxy (MBE) is the only method to date to allow atomically abrupt epitaxial interfaces between conducting oxides and conventional semiconductors such as Si and GaAs. [26] Such abrupt interfaces are crucial for efficient transport of charge across the interface. [27-29] Furthermore, MBE is a scalable method that is being used by the industry The correlated metal SrVO 3 is an attractive earth-abundant transparent conducting oxide (TCO), a critical component of many optoelectronic and renewable energy devices. A key challenge is to synthesize films with low resistivity, due to the prevalence of defects that cause electron scattering. In addition to the material's promise as a TCO, its interesting correlated-electron physics is often obscured by a high defect concentration, which inhibits its further development into new types of devices. A rou...

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Section: Transport Properties Of the Sample With The Highest Rrr Valumentioning

confidence: 64%

“…Precipitates of foreign phases have been observed and analyzed by others in off-stoichiometric films. [12,36] While we were unable to observe such defects in our off-stoichiometric films, in such proximity to 1:1 stoichiometry they might have a low volume fraction, below the detection of XRD.…”

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confidence: 59%

Scalable Synthesis of the Transparent Conductive Oxide SrVO₃

Shoham

Baskin

Han

et al. 2019

Adv Elect Materials

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“…"V2p 3/2 (5+)" exhibits an increase up to 60% at 70°, conversely to the decrease of "V2p 3/2 (4+)" and "V2p 3/2 (3+)" down to 20% at 70°. It indicates that the Srrich surface is also accompanied by a proportion of V 5+ , probably related to V 2 O 5 surface oxide [49], two phases which are impossible to distinguish at this step. Finally, we observe in figure 5c.…”

Section: Figure 2bmentioning

confidence: 98%

“…Such high values highlight the fact that as-grown SVO is strongly governed by Sr-rich phases which can be assimilated to SrO in excess. This phenomenon is commonly explained by a Sr segregation in the first nanometers [47,49], and seems to be inherent to all physical growth process.…”

Section: Figure 2bmentioning

confidence: 99%

XPS monitoring of SrVO3 thin films from demixing to air ageing: The asset of treatment in water

Bourlier

Frégnaux

Bérini

et al. 2021

Applied Surface Science

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In this work, 40 nm-thick films of SrVO 3 (SVO) grown by Pulsed Laser Deposition (PLD) on SrTiO 3 substrates are studied by X-Ray Photoelectron Spectroscopy (XPS). We develop here a systematic fitting procedure for both Sr3d, V2p 3/2 and O1s spectral regions of interest associated to the different chemical environments. Joint angle resolved XPS and Ar ion depth profiling reveal that as-grown SVO thin films exhibits Sr-rich phases at the extreme surface and a near-stoichiometric SVO in the bulk. The removal of segregated Sr is proposed by a treatment in deionized ultrapure water. This step will become an essential technological step in order to obtain reproducible surfaces achieving a stoichiometric SVO oxide phase. Besides, these hydrolyzed SVO surfaces appears VO 2 terminated and then more electrically active. Furthermore, an air-ageing comparative study between as-grown and H 2 O-treated samples reveals that hydrolyzed surfaces are more surface sensitive to air oxidation. Such observations will be crucial and must be carefully considered before performing any passivation process for the integration of SVO thin film into next generation electronics heterostructures.

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“…This Srrich ratio from the SVO layer is in good agreement with a previous study evidencing that Sr-rich phases exist at the extreme surface of these SVO thin films. [55] As Sr-rich phases were found to be readily soluble in water, this will be an asset for its use as a SL. Figure 2c represents AFM analyses of the STO and SVO surfaces.…”

Section: B Study Of Srvo 3 and Srtio 3 Nanothick Layers During Transfermentioning

confidence: 99%

Transfer of Epitaxial SrTiO₃ Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides

Bourlier

Bérini

Frégnaux

et al. 2020

ACS Appl. Mater. Interfaces

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Integration of functional thin film materials with adapted properties is essential for the development of new paradigms in information technology. Among them, complex oxides with perovskite structures have huge potential based on the particularly large diversity of physical properties. Here we demonstrate the possibility of transferring perovskite oxide materials like SrTiO 3 onto silicon substrate using an environmentally friendly process at nanoscale, by means of a water-soluble perovskite sacrificial layer: SrVO 3. Based on in situ monitoring atomic force microscopy and photoemission studies, we reveal that dissolution is initiated from a strontium rich phase at the extreme surface of SrVO 3. The transferred nanothick SrTiO 3 layer on silicon presents an effective morphology and monocrystalline quality, providing a proof of concept for the integration and development of an all perovskite oxide electronics or "oxitronics" onto any Si-based substrates.

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Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO₃ Thin‐Films Grown by Pulsed Laser Deposition

Cited by 15 publications

References 64 publications

Scalable Synthesis of the Transparent Conductive Oxide SrVO₃

Scalable Synthesis of the Transparent Conductive Oxide SrVO₃

XPS monitoring of SrVO3 thin films from demixing to air ageing: The asset of treatment in water

Transfer of Epitaxial SrTiO₃ Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides

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Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO3 Thin‐Films Grown by Pulsed Laser Deposition

Cited by 15 publications

References 64 publications

Scalable Synthesis of the Transparent Conductive Oxide SrVO3

Scalable Synthesis of the Transparent Conductive Oxide SrVO3

XPS monitoring of SrVO3 thin films from demixing to air ageing: The asset of treatment in water

Transfer of Epitaxial SrTiO3 Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides

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Surface Characterizations and Selective Etching of Sr‐Rich Segregation on Top of SrVO₃ Thin‐Films Grown by Pulsed Laser Deposition

Scalable Synthesis of the Transparent Conductive Oxide SrVO₃

Scalable Synthesis of the Transparent Conductive Oxide SrVO₃

Transfer of Epitaxial SrTiO₃ Nanothick Layers Using Water-Soluble Sacrificial Perovskite Oxides