A synchrotron-based photoemission study of the MoO3/Co interface

Wang, Yuzhan; Yang, Ming; Qi, Dongchen; Chen, Shi; Chen, Wei; Wee, Andrew Thye Shen; Gao, Xingyu

doi:10.1063/1.3546034

Cited by 16 publications

(9 citation statements)

References 33 publications

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“…In Figure a, the work function of pristine VSe 2 is 4.70 eV, but we found that it varies from 4.70 to 5.10 eV depending on the coverage of VSe 2 on HOPG (see Figure S1). Upon deposition of MoO 3 , the work function gradually increases and reaches 6.43 eV at 14 Å MoO 3 thickness, close to the reported saturation work function (∼6.50–6.86 eV) of MoO 3 , − indicating a complete coverage by MoO 3 , consistent with our STM data. A close inspection of the SECO spectra for 0.5, 1, and 2 Å MoO 3 thicknesses reveals two sets of cutoff edges, which arise from the nonuniform coverage of MoO 3 as a result of the island growth mode.…”

Section: Resultssupporting

confidence: 90%

“…In other words, monolayer VSe 2 behaves like a noble metal. The band alignment at the MoO 3 –VSe 2 interface is proposed in Figure , in which we take the work function of MoO 3 as 6.6 eV according to the literature, − whereas the work function of monolayer VSe 2 is 5.1 eV, the largest experimental value obtained in this work. Without loss of generality, the band gap of MoO 3 is assumed to be 3.0 eV (averaged from the reported values ,,− ), and the energy difference between the VB maximum (VBM) and Fermi level is 2.5 eV, as determined from Figure .…”

Section: Resultsmentioning

confidence: 95%

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Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe₂ with MoO₃ and K?

Zhang

Xing

et al. 2019

ACS Appl. Mater. Interfaces

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Being a metallic transition-metal dichalcogenide, monolayer vanadium diselenide (VSe2) exhibits many novel properties, such as charge density waves and magnetism. Its interfaces with other materials can potentially be used in device applications as well as for manipulating its intrinsic properties. Here, we present a scanning tunneling microscopy and synchrotron-based X-ray photoemission spectroscopy study of the surface charge-transfer doping using efficient electron-withdrawing and electron-donating materials, that is, molybdenum trioxide (MoO3) and potassium (K), on the molecular beam epitaxy-grown monolayer VSe2 on highly oriented pyrolytic graphite (HOPG). We demonstrate that monolayer VSe2 is immune to MoO3- and K-doping effects. However, at the monolayer edges where the local chemical reactivity is higher because of Se deficiency, MoO3 is seen to react with VSe2 to form molybdenum dioxide (MoO2) and vanadium dioxide (VO2). Compared to the obvious charge-transfer doping effects of MoO3 and K on HOPG, the electronic structure of monolayer VSe2 is barely perturbed. This is attributed to the large density of states at the Fermi level of monolayer VSe2 carrying the metallic character. This work provides new insights into the chemical and electronic properties of monolayer VSe2, important for future VSe2-based electronic device design.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 95%

Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe₂ with MoO₃ and K?

Zhang

Xing

et al. 2019

ACS Appl. Mater. Interfaces

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“…A number of studies have demonstrated chemical interactions between oxides and metal electrodeswithin the first few nanometers of an interface-and also dependence of device performance on the electrode material. 66,70,[218][219][220][221][222] Chemically reactive interfaces can give rise to reduction of oxidation state in the oxide buffer layer near the electrode/buffer interface. For instance, MoO 3 on metals with various reactivity gives rise to reduced MoO 3 near the metal/metal-oxide interface, as illustrated in Figure 13.…”

Section: Opportunities and Challenges Of Metal Oxides As Ultrathin Bumentioning

confidence: 99%

Thin-film metal oxides in organic semiconductor devices: their electronic structures, work functions and interfaces

2013

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Thin-film metal oxides are among the key materials used in organic semiconductor devices. As there are no intrinsic charge carriers in a typical organic semiconductor, all charges in the device must be injected from electrode/organic interfaces, whose energetic structure consequentially dictates the performance of devices. The energy barrier at the interface depends critically on the work function of the electrode. For this reason, various types of thin-film metal oxides can be used as a buffer layer to modify the electrode work function. This paper provides a review on recent progress in metal oxide/organic interface energetics, oxide valence structure and work function, as well as the impact of defects and interfacial reactions on oxide work functions. This review provides a rational guide to process engineers in selecting the best suitable electrode/oxide structures for a targeted applications.

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“…A 3.5 Å thick Co oxide layer was found also in the interfacial region of ultra-thin chromia films grown on the Co(0001) surface [182]. Wang et al studied the MoO 3 /Co layered system, finding a reduction of the oxidation state of Mo in the interfacial region, along with the formation of Co oxide [183].…”

Section: Late 3d Transition Metals Substratesmentioning

confidence: 99%

Reactive metal–oxide interfaces: A microscopic view

Picone

Riva

Brambilla

et al. 2016

Surface Science Reports

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Metal-oxide interfaces play a fundamental role in determining the functional properties of artificial layered heterostructures, which are at the root of present and future technological applications. Magnetic exchange and magnetoelectric coupling, spin filtering, metal passivation, catalytic activity of oxide-supported nano-particles are just few examples of physical and chemical processes arising at metal-oxide hybrid systems, readily exploited in working devices. These phenomena are strictly correlated with the chemical and structural characteristics of the metal-oxide interfacial region, making a thorough understanding of the atomistic mechanisms responsible of its formation a prerequisite in order to tailor the device properties. The steep compositional gradient established upon formation of metal-oxide heterostructures drives strong chemical interactions at the interface, making the metal-oxide boundary region a complex system to treat, both from an experimental and a theoretical point of view. However, once properly mastered, interfacial chemical interactions offer a further degree of freedom for tuning the material properties. The goal of the present review is to provide a summary of the latest achievements in the understanding of metal/oxide and oxide/metal layered systems characterized by reactive interfaces. The influence of the interface composition on the structural, electronic and magnetic properties will be highlighted. Particular emphasis will be devoted to the discussion of ultra-thin epitaxial oxides stabilized on highly oxidizable metals, which have been rarely exploited as oxide supports as compared to the much more widespread noble and quasi noble metallic substrates. In this frame, an extensive discussion is devoted to the microscopic characterization of interfaces between epitaxial metal oxides and the Fe(001) substrate, regarded from the one hand as a prototypical ferromagnetic material and from the other hand as a highly oxidizable metal.

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A synchrotron-based photoemission study of the MoO3/Co interface

Cited by 16 publications

References 33 publications

Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe₂ with MoO₃ and K?

Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe₂ with MoO₃ and K?

Thin-film metal oxides in organic semiconductor devices: their electronic structures, work functions and interfaces

Reactive metal–oxide interfaces: A microscopic view

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A synchrotron-based photoemission study of the MoO3/Co interface

Cited by 16 publications

References 33 publications

Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe2 with MoO3 and K?

Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe2 with MoO3 and K?

Thin-film metal oxides in organic semiconductor devices: their electronic structures, work functions and interfaces

Reactive metal–oxide interfaces: A microscopic view

Contact Info

Product

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Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe₂ with MoO₃ and K?

Is Charge-Transfer Doping Possible at the Interfaces of Monolayer VSe₂ with MoO₃ and K?