The multi-surface structure and catalytic properties of partially reduced WO3, WO2 and WC + O2 or W + O2 as characterized by XPS

Katrib, A.; Hemming, F.; Wehrer, P.; Hilaire, L.; Maire, G.

doi:10.1016/0368-2048(95)02451-4

Cited by 183 publications

(76 citation statements)

References 6 publications

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“…It is therefore necessary to consider the presence of WO x at the metal-WSe 2 interface as a typical device fabrication process will involve contact metal deposition under HV conditions. The binding energy exhibited by the W x+ chemical state in WO x following Au, Ir and Cr deposition under HV conditions suggests x = 5 as these binding energies are between that previously detected from the W 6+ and W 4+ chemical states in WO 3 and WO 2 , respectively [45]. In addition, WO x detected at each metal-WSe 2 interface exhibits O:W ratios between 2.6:1 and 2.7:1.…”

Section: Cr-wse 2 : Substantial Oxidation Of Low-φ Metal and Associatmentioning

confidence: 82%

WSe ₂ -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

et al. 2017

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Contact metals (Au, Ir, and Cr) are deposited on bulk WSe 2 under ultra-high vacuum (UHV, 1 × 10 −9 mbar) and high vacuum (HV, 5 × 10 −6 mbar) conditions and subsequently characterized with x-ray photoelectron spectroscopy (XPS) to elucidate the effects of reactor base pressure on resulting interface chemistry, contact chemistry, and band alignment. Au forms a van der Waals interface with WSe 2 regardless of deposition chamber ambient. In contrast, Ir and Cr form a covalent interface by reducing WSe 2 to form interfacial metal selenides. When Cr is deposited under HV conditions, significant oxygen incorporation is observed resulting in the thermodynamically favorable formation of tungsten oxyselenide and a substantial concentration of Cr x O y . Regardless of contact metal, WO x (2.63 < x < 2.92) forms during deposition under HV conditions which may positively affect interface transport properties. Cr and Ir form unexpectedly large electron and hole Schottky barriers, respectively, when deposited under UHV conditions due to interfacial reactions that contribute to anomalous band alignment. These results reveal the true interface chemistry formed between metals and WSe 2 under UHV and HV conditions and demonstrate the impact on the Fermi level position following contact formation on WSe 2 . PAPEROriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.

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Section: Cr-wse 2 : Substantial Oxidation Of Low-φ Metal and Associatmentioning

confidence: 82%

WSe ₂ -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

et al. 2017

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“…7e f, respectively. The binding energy of O1s of oxygen atoms O 2− is located at 530.87 and 530.6 eV in the bleached and colored states, respectively [35,36]. This O 1s peak is assigned to the oxygen atoms that form the strong W=O bonds in the oxide.…”

Section: Electrochemical Properties Of Wo 3 Film Annealed At 250°cmentioning

confidence: 98%

Efficient electrochromic device based on sol–gel prepared WO3 films

Zhao

Zhang

Dong

et al. 2015

Ionics

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Tungsten oxide (WO 3 ) films were prepared on indium-tin oxide (ITO) glass by sol-gel method. The influence of annealing temperature on the structural, morphological, optical, electrochemical, and electrochromic properties has been investigated. The film annealed at 250°C with an amorphous structure exhibits a noticeable electrochromic performance, such as the highest optical modulation of 58.5 % at 550 nm, high electrochemical stability, and excellent reversibility (Q b /Q c =96.3 %). An electrochromic (EC) device based on WO 3 /NiO complementary structure shows improved performance. It exhibits high optical transmittance modulation of 62 % at 550 nm, excellent cycling stability, and relatively fast electrochromic response time (10 s for coloration and 19 s for bleaching).

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“…On the other hand, bonding with transition metals produces peaks at lower energies than the sp 3 peak of carbon e.g. for Cr [49], Mo [39], Nb [39] or W [54,55], suggesting that the observed subpeaks can be attributed to the respective metal carbides. Moreover, the measurements are made on sub-nmsized layers, i.e.…”

Section: Xps On Ultra Thin Films Of Cr and Momentioning

confidence: 99%

Thermal boundary conductance between refractory metal carbides and diamond

Monachon

Weber

2014

Acta Materialia

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The Thermal Boundary Conductance (TBC) between thin films of Cr, Mo, Nb and W and diamond substrates has been measured using time domain thermoreflectance before and after a high-vacuum heat treatment at 800 o C for 2 h. While no signs of carbide formation could be detected in as-deposited layers by Scanning Transmission Electron Microscopy Energy Dispersive Xray spectroscopy (STEM-EDX) elemental analysis, the heat treatment led to partial (W, Mo) or full conversion (Cr, Nb) of the film into carbide. The measured TBC values on as-deposited samples of 315, 220, 220 and 205 MWm −2 K −1 measured for, respectively, the Cr, Mo, Nb and W samples, were found to not be significantly altered by the heat treatment.

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The multi-surface structure and catalytic properties of partially reduced WO3, WO2 and WC + O2 or W + O2 as characterized by XPS

Cited by 183 publications

References 6 publications

WSe ₂ -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

WSe ₂ -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

Efficient electrochromic device based on sol–gel prepared WO3 films

Thermal boundary conductance between refractory metal carbides and diamond

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The multi-surface structure and catalytic properties of partially reduced WO3, WO2 and WC + O2 or W + O2 as characterized by XPS

Cited by 183 publications

References 6 publications

WSe 2 -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

WSe 2 -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

Efficient electrochromic device based on sol–gel prepared WO3 films

Thermal boundary conductance between refractory metal carbides and diamond

Contact Info

Product

Resources

About

WSe ₂ -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

WSe ₂ -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions