2-D Material Molybdenum Disulfide Analyzed by XPS

Ganta, D.; Sinha, Susmita; Haasch, Richard T.

doi:10.1116/11.20140401

Cited by 159 publications

(143 citation statements)

References 7 publications

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“…The lower binding energy (B.E.) doublet is ascribed to MoS 2 , with the 3d 5/2 and 3d 3/2 spin-orbit components positioned at 229.1 eV and 232.3 eV (Δ=3.15 eV), respectively, comparable to values reported for natural MoS 2 crystals 45 . Oxidized Mo is observed as a higher B.E.…”

Section: Resultssupporting

confidence: 74%

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Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS₂ by Pulsed Metal–Organic Chemical Vapor Deposition

et al. 2017

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High volume manufacturing of devices based on transition metal dichalcogenide (TMD) ultra-thin films will require deposition techniques that are capable of reproducible wafer-scale growth with monolayer control. To date, TMD growth efforts have largely relied upon sublimation and transport of solid precursors with minimal control over vapor phase flux and gas-phase chemistry, which are critical for scaling up laboratory processes to manufacturing settings. To address these issues, we report a new pulsed metalorganic chemical vapor deposition (MOCVD) route for MoS2 film growth in a research-grade single-wafer reactor. Using bis(tert-butylimido)-bis(dimethylamido)molybdenum and diethyl disulfide we deposit MoS2 films from ≈ 1 nm to ≈ 25 nm in thickness on SiO2/Si substrates. We show that layered 2H-MoS2 can be produced at comparatively low reaction temperatures of 591 °C at short deposition times, approximately 90 s for few-layer films. In addition to the growth studies performed on SiO2/Si, films with wafer-level uniformity are demonstrated on 50 mm quartz wafers. Process chemistry and impurity incorporation from precursors are also discussed. This low-temperature and fast process highlights the opportunities presented by metalorganic reagents in the controlled synthesis of TMDs.

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Section: Resultssupporting

confidence: 74%

“…Spectra were acquired at an analyzer pass energy of 40 eV and the analysis area was approximately 1 mm by 0.5 mm. Spectra were charge calibrated against S 2p 3/2 (S-Mo, 162.0 eV) assigned to MoS 2 45 . A low energy electron gun was used for charge neutralization.…”

Section: Experimental Methodsmentioning

confidence: 99%

Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS₂ by Pulsed Metal–Organic Chemical Vapor Deposition

et al. 2017

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“…On one region (L2), the expected peaks of Mo 3d 5/2 (S 2p 3/2 ) corresponding to n-type MoS 2 are measured at 229.7 eV (162.55 eV), in agreement with the reported binding energies. 12,54 Concurrently, a second feature at lower binding energy is also identified confirming the presence of the second component that may be responsible for the p-type behavior, with core levels shifted to 229.2 eV (162.05 eV) for Mo 3d 5/2 (S 2p 3/2 ). On another area (L1), XPS measurements indicate the presence of both features, expressed by two pronounced single peaks Mo 3d 5/2 (S 2p 3/2 ) located at 229.0 eV (161.9 eV) for p-type peak and at 229.7 eV (162.55 eV) for n-type peak.…”

Section: Resultsmentioning

confidence: 86%

Impurities and Electronic Property Variations of Natural MoS₂Crystal Surfaces

et al. 2015

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Room temperature X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), high resolution Rutherford backscattering spectrometry (HR-RBS), Kelvin probe method, and scanning tunneling microscopy (STM) are employed to study the properties of a freshly exfoliated surface of geological MoS2 crystals. Our findings reveal that the semiconductor 2H-MoS2 exhibits both n- and p-type behavior, and the work function as measured by the Kelvin probe is found to vary from 4.4 to 5.3 eV. The presence of impurities in parts-per-million (ppm) and a surface defect density of up to 8% of the total area could explain the variation of the Fermi level position. High resolution RBS data also show a large variation in the MoSx composition (1.8 < x < 2.05) at the surface. Thus, the variation in the conductivity, the work function, and stoichiometry across small areas of MoS2 will have to be controlled during crystal growth in order to provide high quality uniform materials for future device fabrication.

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“…[25][26] During self-doped (PTSa) polymerization of monomer such as aniline, the sulphonate group in oxidant PTSa is reduced from +6 to +4 to form SO 2 11 and the PANI is free from sulphur oxidant which is an advantage of electropolymerization over chemical synthesis. The S 2p spectra could be assigned to the formation of SO 2 during electropolymerization.…”

Section: X-ray Photoelectron Spectroscopy (Xps) Studiesmentioning

confidence: 99%

Electrochemical synthesis of polyaniline cross-linked NiMoO₄ nanofibre dendrites for energy storage devices

Ramkumar

Minakshi

2016

New J. Chem.

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Electrochemical synthesis of polyaniline deposited on a graphite electrode using ptoluenesulfonic acid has been carried out via potentiodynamic method. The feasibility to store energy in polyaniline has been demonstrated in 1 M Na 2 SO 4 electrolyte using cyclic voltammetry and charge-discharge analyses. The obtained low capacitance (247 mF cm -2 ) for polyaniline limits its practical application. Thereon, as an alternative approach, aniline is polymerized in the presence of novel non-ionic surfactant (Quillaja Saponin) and found a marginal increase in capacitance to 342 mF cm -2 . Adsorption of surfactant on aniline resulted in a profound effect on electrochemical behaviour. To further enhance the capacitance, innovatively, polyaniline is cross-linked with nickel molybdate (NiMoO 4 ) using chitosan as biopolymer. The cross-linked NiMoO 4 showed an improved areal specific capacitance of 1250 mF cm -2 and 85% of its initial capacitance is retained after 2000 cycles. The morphology of the cross-linked NiMoO 4 deduced through field emission scanning and transmission electron microscopes showed the formation of nanofibre like dendrite having porous network. The intra molecular interactions that facilitate the electron transfer path with more active sites for nucleation are attributed to higher capacitance. X-ray photoelectron spectroscopy measurements ascertain the presence of NiMoO 4 in the aniline composite after electropolymerization process. Overall, the role of surfactant exhibited the surface functionality whereas biopolymer tuned the redox reactions of NiMoO 4 electrode.An effective cross-linking strategy for grafting polyaniline with a nanomaterial such as nickel molybdate provides long term cyclability in the fabricated energy storage device.

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2-D Material Molybdenum Disulfide Analyzed by XPS

Cited by 159 publications

References 7 publications

Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS₂ by Pulsed Metal–Organic Chemical Vapor Deposition

Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS₂ by Pulsed Metal–Organic Chemical Vapor Deposition

Impurities and Electronic Property Variations of Natural MoS₂Crystal Surfaces

Electrochemical synthesis of polyaniline cross-linked NiMoO₄ nanofibre dendrites for energy storage devices

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2-D Material Molybdenum Disulfide Analyzed by XPS

Cited by 159 publications

References 7 publications

Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS2 by Pulsed Metal–Organic Chemical Vapor Deposition

Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS2 by Pulsed Metal–Organic Chemical Vapor Deposition

Impurities and Electronic Property Variations of Natural MoS2Crystal Surfaces

Electrochemical synthesis of polyaniline cross-linked NiMoO4 nanofibre dendrites for energy storage devices

Contact Info

Product

Resources

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Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS₂ by Pulsed Metal–Organic Chemical Vapor Deposition

Rapid Wafer-Scale Growth of Polycrystalline 2H-MoS₂ by Pulsed Metal–Organic Chemical Vapor Deposition

Impurities and Electronic Property Variations of Natural MoS₂Crystal Surfaces

Electrochemical synthesis of polyaniline cross-linked NiMoO₄ nanofibre dendrites for energy storage devices