Electronic properties of cleaved molybdenum disulphide surfaces

McGovern, I.T.; Williams, R. H.; Mee, C. H. B.

doi:10.1016/0039-6028(74)90318-5

Cited by 29 publications

(20 citation statements)

References 14 publications

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“…Reported values of the work function for MoS 2 , ϕ MoS 2 , range from 4.48 eV to 5.2 eV11121314. The literature values for polycrystalline Au and Pd work functions, ϕ Au and ϕ Pd , are very similar, about 5.1 eV151617.…”

Section: Resultsmentioning

confidence: 92%

Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

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Deppe

Boyd

et al. 2013

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Semiconducting molybdenum disulfphide has emerged as an attractive material for novel nanoscale optoelectronic devices due to its reduced dimensionality and large direct bandgap. Since optoelectronic devices require electron-hole generation/recombination, it is important to be able to fabricate ambipolar transistors to investigate charge transport both in the conduction band and in the valence band. Although n-type transistor operation for single-layer and few-layer MoS2 with gold source and drain contacts was recently demonstrated, transport in the valence band has been elusive for solid-state devices. Here we show that a multi-layer MoS2 channel can be hole-doped by palladium contacts, yielding MoS2 p-type transistors. When two different materials are used for the source and drain contacts, for example hole-doping Pd and electron-doping Au, the Schottky junctions formed at the MoS2 contacts produce a clear photovoltaic effect.

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Section: Resultsmentioning

confidence: 92%

Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

Fontana

Deppe

Boyd

et al. 2013

Sci Rep

466

450

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“…However, p-type behavior was also reported on bulk crystals. 12,[23][24]37 . The 2H-MoS 2 phase is the most stable among the three established polytypes of MoS 2 (1T, 2H, and 3R) 38 and it is also well known that the intercalation of alkali metals such as Li, Na, or K into 2H-MoS 2 cause a phase transformation to the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 distorted 1T'-MoS 2 which exhibits a metallic nature.…”

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confidence: 98%

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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“…Although MoS 2 films can be synthesized nowadays by chemical vapor deposition (CVD) [11,12] and other techniques [13,14], there are still many studies that use mechanically exfoliated films from mineral crystals for the measurement of physical properties [5][6][7][15][16][17][18][19]. Even though the mineral crystals are more or less considered to be inert, there have been few studies on the impurities of MoS 2 surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…Even though the mineral crystals are more or less considered to be inert, there have been few studies on the impurities of MoS 2 surfaces. Carbon contamination was reported to affect the band-bending of the MoS 2 crystal [15], and the change of the work function suggests contamination of the surface [18,19]. The desorption of sulfur atoms from MoS 2 by annealing [20] and vacancy formation [21], and changes in polytypism [22] by exposure to an electron beam could indicate a certain instability of the surface.…”

Section: Introductionmentioning

confidence: 99%

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PEEM and Micro-UPS Studies of Cleaved and Exfoliated Molybdenum Disulfide Surfaces

Kadowaki

Sano

Abukawa

2017

e-J. Surf. Sci. Nanotech.

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Thin films of molybdenum disulfide (MoS2) are generally exfoliated from a mineral crystal. Impurities and contaminants of mineral origin may spoil the expected functions of MoS2 thin-film devices because they have a strong influence on the properties of the exfoliated films. The effects of surface contaminants on cleaved or exfoliated MoS2 surfaces were investigated using photoemission electron microscopy and selected-area ultraviolet photoelectron spectroscopy under several exfoliation conditions. The chemical composition and crystallinity of surfaces were also investigated using Auger electron spectroscopy and electron diffraction. The bulk crystal included a limited number of contaminated interfaces, at which the crystal was easily cleaved. Therefore, repeated exfoliations are required to expose a clean surface for exfoliated films. Annealing at ca. 400• C in a vacuum was effective to reduce contamination of the cleaved MoS2 surface.

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Electronic properties of cleaved molybdenum disulphide surfaces

Cited by 29 publications

References 14 publications

Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

Impurities and Electronic Property Variations of Natural MoS₂Crystal Surfaces

PEEM and Micro-UPS Studies of Cleaved and Exfoliated Molybdenum Disulfide Surfaces

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Electronic properties of cleaved molybdenum disulphide surfaces

Cited by 29 publications

References 14 publications

Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

Electron-hole transport and photovoltaic effect in gated MoS2 Schottky junctions

Impurities and Electronic Property Variations of Natural MoS2Crystal Surfaces

PEEM and Micro-UPS Studies of Cleaved and Exfoliated Molybdenum Disulfide Surfaces

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Impurities and Electronic Property Variations of Natural MoS₂Crystal Surfaces