Growth and characterization of large, high quality MoSe2 single crystals

Bougouma, Moussa; Batan, Abdelkrim; Guel, Boubié; Segato, Tiriana; Legma, Jean B.; Reniers, François; Delplancke‐Ogletree, Marie‐Paule; Buess‐Herman, C.; Doneux, Thomas

doi:10.1016/j.jcrysgro.2012.10.026

Cited by 53 publications

(34 citation statements)

References 21 publications

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“…Figure 4b shows the conductivity as a function of the thickness (σ-t). The value of σ increases by over two orders of magnitude, from 4.6 to 1,500 Ω ) [36][37][38] for the thickness in the bulk region (t: 10-100 μm) are also located on the fitted line.…”

Section: Representative Resultsmentioning

confidence: 82%

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Chen

Tang

Shen

et al. 2015

JoVE

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Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal-semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω(-) (1) cm(-) (1), with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

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Section: Representative Resultsmentioning

confidence: 82%

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Chen

Tang

Shen

et al. 2015

JoVE

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“…An AFM phase image of the samples (Fig. S1, Supporting Information) reveals that the surface of the SiO 2 /Si substrate is not completely covered by MoSe 2 possibly due to the loss of Se and Mo and agglomeration during the rapid heating and annealing . It has been reported that annealing temperatures higher than 700 °C lead to enhanced layer growth of MoSe 2 .…”

Section: Resultsmentioning

confidence: 99%

Synthesis, characterization, and electronic structure of few-layer MoSe₂ granular films

Wickramaratne

Bay

Favors

et al. 2014

Phys. Status Solidi A

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Few-layer MoSe 2 granular films were prepared using rapid thermal processing (RTP) of stacked elemental layers (SELs) deposited using electron beam evaporation in the sequence of Mo/Se/Mo. RTP was carried out at various temperatures ranging from 550 to 750 8C, and durations ranging from 90 to 150 s. Morphology and microstructure of granular thin films were characterized by atomic force microscopy and scanning electron microscopy. Compositional and electronic structure analysis of the films were done by X-ray photoelectron, photoluminescence and Raman spectroscopy. The results confirmed the formation of four-layer MoSe 2 granular thin films at 750 8C for 90 s. Density functional theory calculations showed that the direct gap at K is near degenerate with the calculated indirect band gap in the 4L structure. In addition to RTP, Raman laser annealing (RLA) was performed on SELs with various laser powers. Raman spectroscopy results reveal the local formation of MoSe 2 with increasing laser energy.

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“…Single crystals of Mo(Se 1−x Te x ) 2 were formed from polycrystalline powder Mo(Se 1−x Te x ) 2 samples by chemical vapor transport using a furnace with different temperature zones [30]; powder Mo(Se 1−x Te x ) 2 samples were prepared by annealing stoichiometric amounts of Mo, Se, and Te powder at 800…”

Section: Methodsmentioning

confidence: 99%

“…• C for 5 d using a procedure reported elsewhere [30]. TeCl 4 was mixed with a Mo(Se 1−x Te x ) 2 sample as a transport material for preparing single crystals of Mo(Se 1−x Te x ) 2 .…”

Section: Methodsmentioning

confidence: 99%

Transistor properties of exfoliated single crystals of2H−Mo(Se1−xTe<

et al. 2017

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Field-effect transistors (FETs) were fabricated using exfoliated single crystals of Mo(Se 1−x Te x ) 2 with an x range of 0 to 1, and the transistor properties fully investigated at 295 K in four-terminal measurement mode. The chemical composition and crystal structure of exfoliated single crystals were identified by energy-dispersive x-ray spectroscopy (EDX), single-crystal x-ray diffraction, and Raman scattering, suggesting the 2H -structure in all Mo(Se 1−x Te x ) 2 . The lattice constants of a and c increase monotonically with increasing x, indicating the substitution of Se by Te. When x < 0.4 in a FET with a thin single crystal of Mo(Se 1−x Te x ) 2 , n-channel FET properties were observed, changing to p-channel or ambipolar operation for x > 0.4. In contrast, the polarity of a thick single-crystal Mo(Se 1−x Te x ) 2 FET did not change despite an increase in x. The change of polarity in a thin single-crystal FET was well explained by the variation of electronic structure. The absence of such change in the thick single-crystal FET can be reasonably interpreted based on the large bulk conduction due to naturally accumulated electrons. The μ value in the thin single-crystal FET showed a parabolic variation, with a minimum μ at around x = 0.4, which probably originates from the disorder of the single crystal caused by the partial replacement of Se by Te, i.e., a disorder that may be due to ionic size difference of Se and Te.

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Growth and characterization of large, high quality MoSe2 single crystals

Cited by 53 publications

References 21 publications

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Synthesis, characterization, and electronic structure of few-layer MoSe₂ granular films

Transistor properties of exfoliated single crystals of2H−Mo(Se1−xTe<

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Growth and characterization of large, high quality MoSe2 single crystals

Cited by 53 publications

References 21 publications

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Synthesis, characterization, and electronic structure of few-layer MoSe2 granular films

Transistor properties of exfoliated single crystals of2H−Mo(Se1−xTe<

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Synthesis, characterization, and electronic structure of few-layer MoSe₂ granular films