The investigation of NbO2 and Nb2O5 electronic structure by XPS, UPS and first principles methods

Zhang, Weibin; Wu, Weidong; Wang, Xueming; Cheng, Xinlu; Yan, Donghang; Shen, Chen; Li-Ping, Peng; Wang, Yuying; Li, Bai

doi:10.1002/sia.5253

Cited by 123 publications

(69 citation statements)

References 46 publications

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“…1b for the 20 mTorr sample can then be ascribed to (101), (181) [10], 0.5 eV [32], 0.7 eV [11], 0.88 eV [33], and at least 1.0 eV [9]. The sample grown in 20 mTorr pressure showed no significant absorption within the photon energy range, in agreement with the higher Nb 2 O 5 band gap energy ranging from 3.5 to 4.8 eV [11,34,35]. The small, broad peaks near 0.65 eV and 0.9 eV are due to water absorption in air.…”

Section: Resultsmentioning

confidence: 99%

“…Recently there has been a growing interest in materials demonstrating metal-insulator transitions (MITs) because of their possible applications in electronic devices [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Among these materials is NbO 2 which exhibits one of the highest MIT temperatures of 1081K [16][17], accompanied by a structural transition from a distorted rutile (low temperature) to a rutile structure (high temperature phase).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Preparation, characterization, and electrical properties of epitaxial NbO₂thin film lateral devices

Joshi¹,

Senty²,

Borisov³

et al. 2015

J. Phys. D: Appl. Phys.

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Epitaxial NbO 2 (110) films, 20 nm thick, were grown by pulsed laser deposition on Al 2 O 3 (0001) substrates. The Ar/O 2 total pressure during growth was varied to demonstrate the gradual transformation between NbO 2 and Nb 2 O 5 phases, which was verified using x-ray diffraction, x-ray photoelectron spectroscopy, and optical absorption measurements. Electric resistance threshold switching characteristics were studied in a lateral geometry using interdigitated Pt top electrodes in order to preserve the epitaxial crystalline quality of the films.Volatile and reversible transitions between high and low resistance states were observed in epitaxial NbO 2 films, while irreversible transitions were found in case of Nb 2 O 5 phase. Electric field pulsed current measurements confirmed thermally-induced threshold switching.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation, characterization, and electrical properties of epitaxial NbO₂thin film lateral devices

Joshi¹,

Senty²,

Borisov³

et al. 2015

J. Phys. D: Appl. Phys.

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“…Any particular niobate or tantalate can be characterized by a set of binding energies (BE) related to maximums of Nb 3d or Ta 4f and O 1s lines. However, a significant scattering exists in binding energy values reported in the literature Nb 3d 3/2 (210 eV) and Nb 3d 5/2 (207 eV) or Ta 4f 5/2 (28 eV) and Ta 4f 7/2 (26 eV) components even for such stable compounds as Nb 2 O 5 or Ta 2 O 5 . The binding energy differences Δ(O―Nb) = B E (O 1s) − B E (Nb 3d 5/2 ) and Δ(O―Ta) = B E (O 1s) − B E (Ta 4f 7/2 ) are suitable parameters to characterize average Nb―O bonding in niobates (322.2‐323.6 eV) and Ta―O bonding in tantalates (502.7‐504.4 eV) …”

Section: Introductionmentioning

confidence: 97%

X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films

Bruncková

Kolev

Kaňuchová

2018

Surface & Interface Analysis

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Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol‐gel/spin‐coating process on Al2O3 substrate with LaNbO4/PbZrO3 interlayer and annealing at 1000°C. Surface chemistry was investigated by X‐ray photoelectron spectroscopy (XPS). The core‐level XPS studies of sol‐gel NNO and NTO were performed for the first time. The binding energy differences Δ(O―Nb) and Δ(O―Ta) were used to characterize average energies of Nb―O bonding in NNO (322.9 eV) and Ta―O bonding in NTO (504.2 eV). The XPS demonstrated single valence state of Nd (Nd3+) in precursors. Nd concentration (at. %) decreases from 22% in precursors to 7% in films considering the substrate contains C, Al, Si, Pb, and Zr elements (37%) at Nb or Ta (5%) and O (51%). The X‐ray diffraction analyses verified formation of the monoclinic (M‐NdNbO4 or M′‐NdTaO4), orthorhombic (O‐NdNbO4) and tetragonal (T‐NdTaO4) phases in precursors and films. Single valence state of Nd3+ was confirmed in these films designed for the application in environmental electrolytic thin film devices.

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“…Oxide films of niobium and its compounds are covered by a great amount of works, i.e. [2][3][4][5]. However, there are no works covering layer phase profiling of oxidized thin films of niobium compounds.…”

mentioning

confidence: 99%

An XPS method for layer profiling of NbN thin films

et al. 2016

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Abstract. Layer chemical and phase profiling of niobium nitride thin films on a silicon substrate oxidized on air was performed with the help of a method designed by us. The method includes: a new method of background subtraction of multiple inelastically scattered photoelectrons considering depth inhomogeneity of electron inelastic scattering; a new method of photoelectron line decomposition into component peaks considering physical nature of different decomposition parameters; joint solution of the background subtraction and photoelectron line decomposition problems; control of line decomposition accuracy with the help of a suggested performance criterion; calculation of layer thicknesses for a multilayer target using a simple formula.The interest in thin films of niobium and its compounds is caused by their superconductive properties used in cryogenic electronic instrumentation. For example, niobium nitride thin films are attracting rising attention in recent submillimeter and THz receiver research [1]. As an oxidation result of films of niobium or its compounds (originally homogeneous) multilayer and multiphase films are built. The superconductive properties of niobium compounds become worse with increase of surface niobium oxide layer thickness. Oxide films of niobium and its compounds are covered by a great amount of works, i.e. [2][3][4][5]. However, there are no works covering layer phase profiling of oxidized thin films of niobium compounds.This work presents layer phase profiling of oxidized thin films of niobium nitride on a silicon substrate by the means of XPS. Thin niobium nitride films were sputtered onto a silicon substrate by the magnetron method. The films were oxidized during unload from the vacuum chamber. X-ray photoemission spectra were obtained with the electron-ion spectroscopy module based on the platform Nanofab 25 (NT-MDT). In the analytical chamber, an ultrahigh oil-free vacuum about 10 -8 Pa was achieved. The spectra were recorded with an electrostatic semi-spherical energy analyzer SPECS Phoibos 225.Layer profiling on the base of XPS spectra of multilayer multicomponent thin films interpretation is a complex inverse problem with a lot of unknown parameters. For correct solution of this problem new methods and approaches designed by the authors are suggested:

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The investigation of NbO₂ and Nb₂O₅ electronic structure by XPS, UPS and first principles methods

Cited by 123 publications

References 46 publications

Preparation, characterization, and electrical properties of epitaxial NbO₂thin film lateral devices

Preparation, characterization, and electrical properties of epitaxial NbO₂thin film lateral devices

X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films

An XPS method for layer profiling of NbN thin films

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The investigation of NbO2 and Nb2O5 electronic structure by XPS, UPS and first principles methods

Cited by 123 publications

References 46 publications

Preparation, characterization, and electrical properties of epitaxial NbO2thin film lateral devices

Preparation, characterization, and electrical properties of epitaxial NbO2thin film lateral devices

X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films

An XPS method for layer profiling of NbN thin films

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Product

Resources

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The investigation of NbO₂ and Nb₂O₅ electronic structure by XPS, UPS and first principles methods

Preparation, characterization, and electrical properties of epitaxial NbO₂thin film lateral devices

Preparation, characterization, and electrical properties of epitaxial NbO₂thin film lateral devices