Room-temperature epitaxy of metal thin films on tungsten diselenide

Cooley, Kayla A.; Alsaadi, Rajeh; Gurunathan, Ramya; Domask, Anna C.; Kerstetter, Lauren; Saidi, Wissam A.; Mohney, Suzanne E.

doi:10.1016/j.jcrysgro.2018.09.040

Cited by 14 publications

(15 citation statements)

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“…Therefore, thermodynamic analysis can be carried out for projections of expected metal reactions with selenides and tellurides, and indeed, a recent experimental report of metal epitaxy and reactivity with few-layer WSe 2 was consistent with calculated isothermal phase diagrams. 21 Defect sites may also enhance a 2D material's reactivity, 18,79 which is an important consideration as selenides and tellurides tend to be more defective than sulfides, and CVD-grown 2D materials tend to be more defective than exfoliated 2D materials. 55 Additionally, since the bond energy is weaker for Mo−Te and Mo−Se than Mo−S, 55,80 it is reasonable to expect that they would be even more susceptible to metal evaporation-induced damage and reactions at their contacts.…”

Section: Resultsmentioning

confidence: 99%

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confidence: 88%

“…However, it is unclear how many layers deep the reactions penetrate the 2D material, which is important for contacts to monolayer versus multilayer materials. A previous study points to the lack of interfacial reaction as a requirement for epitaxy of metals on 2D materials, and Ag, Au, Pb, Pd, Pt, Al, Cu, and Zn films were found (by TEM) to grow epitaxially on MoS 2 , indicating that these metals do not react with MoS 2 . Other studies have reported large strain effects from thin (1–3 nm) evaporated metals on MoS 2 using Raman spectroscopy. − However, Raman analysis provides only an indirect measurement of strain by assuming shifts in MoS 2 Raman peaks are solely due to strain, so quantification using a direct lattice constant measurement technique, such as X-ray diffraction (XRD), remains necessary.…”

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Uncovering the Effects of Metal Contacts on Monolayer MoS₂

et al. 2020

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Metal contacts are a key limiter to the electronic performance of two-dimensional (2D) semiconductor devices. Here we present a comprehensive study of contact interfaces between seven metals (Y, Sc, Ag, Al, Ti, Au, Ni, with work functions from 3.1 to 5.2 eV) and monolayer MoS 2 grown by chemical vapor deposition. We evaporate thin metal films onto MoS 2 and study the interfaces by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and electrical characterization. We uncover that, 1) ultrathin oxidized Al dopes MoS 2 ntype (>2×10 12 cm -2 ) without degrading its mobility, 2) Ag, Au, and Ni deposition causes varying levels of damage to MoS 2 (broadening Raman E' peak from <3 cm -1 to >6 cm -1 ), and 3) Ti, Sc, and Y react with MoS 2 . Reactive metals must be avoided in contacts to monolayer MoS 2 , but control studies reveal the reaction is mostly limited to the top layer of multilayer films. Finally, we find that 4) thin metals do not significantly strain MoS 2 , as confirmed by X-ray diffraction. These are important findings for metal contacts to MoS 2 , and broadly applicable to many other 2D semiconductors.

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Uncovering the Effects of Metal Contacts on Monolayer MoS₂

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“…19 Alternatively, 2DC/metal interfaces with crystallographic registry can be formed through van der Waals epitaxy. 20 During physical vapor deposition, thin metal films tend to preferentially align on 2DCs, 21,22 which results in periodic (Moiré) structural and electronic variations at the interface due to the lattice mismatch. We demonstrate a platform that brings together concepts from each of these areas: aligned 2DC/metal interfaces, SPP-exciton coupling, and 2D quantum emitters.…”

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confidence: 99%

Enabling remote quantum emission in 2D semiconductors via porous metallic networks

et al. 2020

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The interaction between two-dimensional crystals (2DCs) and metals is ubiquitous in 2D material research. Here we report how 2DC overlayers influence the recrystallization of relatively thick metal films and the subsequent synergetic benefits this provides for coupling surface plasmon-polaritons (SPPs) to photon emission in 2D semiconductors. We show that annealing 2DC/Au films on SiO2 results in a 'reverse epitaxial' process where initially nanocrystalline Au films become highly textured and in close crystallographic registry to the 2D crystal overlayer.With continued annealing, the metal underlayer dewets to form an oriented pore enabled network (OPEN) film in which the 2DC overlayer remains suspended above or coats the inside of the metal pores. This OPEN film geometry supports SPPs launched by either direct laser excitation or by light emitted from the TMD semiconductor itself, where energy in-coupling and out-coupling occurs at the metal pore sites such that dielectric spacers between the metal and 2DC layer are unnecessary. At low temperatures a high density of single-photon emitters (SPEs) is present across an OPEN-WSe2 film, and we demonstrate non-local excitation of SPEs at a distance of 17 m with minimal loss of photon purity. Our results suggest the OPEN film geometry is a versatile platform that could facilitate the use of layered materials in quantum optics systems.

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“…For example, Cooley et al [4] noted that aluminum does not follow the mechanism of epitaxial growth on WSe 2 crystal surface, unlike such metals as Au, Ag, Cu, Pd and Co. Authors explain this effect with the fact that aluminum forms strong chemical bonds with selenium and becomes immobile on this substrate.…”

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Initial Stages of Metal Films Growth on a SiO2-Cristobalite Surface

Zavodinsky

Kuzmenko

2019

J. Mater. Sci. Technol. Res.

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Using the density functional theory approach and pseudopotentials we studied energetics and electron structures of metal layers (Al, Cu, Ni, and Cr) deposited on a cristobalite surface. We have found that the properties of the first adsorbed layers decide by interaction of metal atoms with oxygen atoms of a substrate surface. Aluminum as an easily oxidized metal, is characterized by the high adhesion, it is followed by nickel and chromium, and copper closes the studied group of metals. Further plating is characterized by significant reduction of binding energy; the properties of films tend to properties of bulk metals.

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Room-temperature epitaxy of metal thin films on tungsten diselenide

Cited by 14 publications

References 36 publications

Uncovering the Effects of Metal Contacts on Monolayer MoS₂

Uncovering the Effects of Metal Contacts on Monolayer MoS₂

Enabling remote quantum emission in 2D semiconductors via porous metallic networks

Initial Stages of Metal Films Growth on a SiO2-Cristobalite Surface

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Room-temperature epitaxy of metal thin films on tungsten diselenide

Cited by 14 publications

References 36 publications

Uncovering the Effects of Metal Contacts on Monolayer MoS2

Uncovering the Effects of Metal Contacts on Monolayer MoS2

Enabling remote quantum emission in 2D semiconductors via porous metallic networks

Initial Stages of Metal Films Growth on a SiO2-Cristobalite Surface

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Product

Resources

About

Uncovering the Effects of Metal Contacts on Monolayer MoS₂

Uncovering the Effects of Metal Contacts on Monolayer MoS₂