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Transition metal dichalcogenide growth via close proximity precursor supply.

O'Brien M, McEvoy N, Hallam T, Kim HY, Berner NC, Hanlon D, Lee K, Coleman JN, Duesberg GS - Sci Rep (2014)

Bottom Line: TMD monolayers were realized using a close proximity precursor supply in a CVD microreactor setup.A model describing the growth mechanism, which is capable of producing TMD monolayers on arbitrary substrates, is presented.Furthermore, through patterning of the precursor supply, we achieve patterned growth of monolayer TMDs in defined locations, which could be adapted for the facile production of electronic device components.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Chemistry, Trinity College Dublin, Dublin 2, Ireland [2] Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and Advanced Materials and BioEngineering Research (AMBER) Centre, Trinity College Dublin, Dublin 2, Ireland.

ABSTRACT
Reliable chemical vapour deposition (CVD) of transition metal dichalcogenides (TMDs) is currently a highly pressing research field, as numerous potential applications rely on the production of high quality films on a macroscopic scale. Here, we show the use of liquid phase exfoliated nanosheets and patterned sputter deposited layers as solid precursors for chemical vapour deposition. TMD monolayers were realized using a close proximity precursor supply in a CVD microreactor setup. A model describing the growth mechanism, which is capable of producing TMD monolayers on arbitrary substrates, is presented. Raman spectroscopy, photoluminescence, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy, scanning electron microscopy and electrical transport measurements reveal the high quality of the TMD samples produced. Furthermore, through patterning of the precursor supply, we achieve patterned growth of monolayer TMDs in defined locations, which could be adapted for the facile production of electronic device components.

No MeSH data available.


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(a) Optical image of as-grown CVD monolayer MoS2 dots (b) Optical image of a MoS2 continuous layer grown by the pattern transfer technique with no observable subsequent island growth on the terminated monolayer. (c) Further enhanced magnification of the area shown in (b) over which Raman and PL scans were taken. Note that the Raman/PL maps are shown at an orientation of 90° to this area. The red box shows the area corresponding to AFM scans. Scale bar is 9 µm (d) A1 exciton maximum photoluminescence map (e) B1 exciton maximum photoluminescence map (f) photoluminescence spectra at points 1 and 2 as indicated in (d), and the average spectrum over the entire scanned area, consisting of 14,400 individual point spectra. (g) Map of E' Raman peak sum (h) Map of A'1 Raman peak sum. Scale bar is 6 µm for all Raman and PL maps. (i) Average Raman spectrum over 14,400 points taken in the scanned area the film, showing a peak separation of 18 cm−1, which is in agreement with literature reports for monolayer MoS2.
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f4: (a) Optical image of as-grown CVD monolayer MoS2 dots (b) Optical image of a MoS2 continuous layer grown by the pattern transfer technique with no observable subsequent island growth on the terminated monolayer. (c) Further enhanced magnification of the area shown in (b) over which Raman and PL scans were taken. Note that the Raman/PL maps are shown at an orientation of 90° to this area. The red box shows the area corresponding to AFM scans. Scale bar is 9 µm (d) A1 exciton maximum photoluminescence map (e) B1 exciton maximum photoluminescence map (f) photoluminescence spectra at points 1 and 2 as indicated in (d), and the average spectrum over the entire scanned area, consisting of 14,400 individual point spectra. (g) Map of E' Raman peak sum (h) Map of A'1 Raman peak sum. Scale bar is 6 µm for all Raman and PL maps. (i) Average Raman spectrum over 14,400 points taken in the scanned area the film, showing a peak separation of 18 cm−1, which is in agreement with literature reports for monolayer MoS2.

Mentions: We have extended this growth procedure to the in-situ CVD patterning of MoS2 by pre-patterning the MoO3 seed layer before synthesis. This was done by sputtering MoO3 layers through a patterned metal shadow mask. This results in patterns of MoS2 monolayers that can be grown directly on a target substrate. The features demonstrated here are circles of closed MoS2 films with a diameter of approximately 100 μm as shown in Fig. 4(a). The resulting patterns are of approximately the same diameter as the original square patterns, with some loss of square structure due to the initial spread of material during sputtering, and then the subsequent evaporation into a vapour source followed by re-deposition as MoS2. This patterned growth is possible due to the close proximity of the oxide precursor. These patterned monolayers have the same high quality as the larger scale films as shown previously in Fig. 1(a). Although the resolution of the process is limited, as shown in Fig. 4(b), by a slight spread in growth, the method can produce multiple patterns without having to expose the monolayers to additional processing steps. This methodology could potentially be used to fabricate channels and other device components without the need for post growth processing steps.


Transition metal dichalcogenide growth via close proximity precursor supply.

O'Brien M, McEvoy N, Hallam T, Kim HY, Berner NC, Hanlon D, Lee K, Coleman JN, Duesberg GS - Sci Rep (2014)

(a) Optical image of as-grown CVD monolayer MoS2 dots (b) Optical image of a MoS2 continuous layer grown by the pattern transfer technique with no observable subsequent island growth on the terminated monolayer. (c) Further enhanced magnification of the area shown in (b) over which Raman and PL scans were taken. Note that the Raman/PL maps are shown at an orientation of 90° to this area. The red box shows the area corresponding to AFM scans. Scale bar is 9 µm (d) A1 exciton maximum photoluminescence map (e) B1 exciton maximum photoluminescence map (f) photoluminescence spectra at points 1 and 2 as indicated in (d), and the average spectrum over the entire scanned area, consisting of 14,400 individual point spectra. (g) Map of E' Raman peak sum (h) Map of A'1 Raman peak sum. Scale bar is 6 µm for all Raman and PL maps. (i) Average Raman spectrum over 14,400 points taken in the scanned area the film, showing a peak separation of 18 cm−1, which is in agreement with literature reports for monolayer MoS2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260218&req=5

f4: (a) Optical image of as-grown CVD monolayer MoS2 dots (b) Optical image of a MoS2 continuous layer grown by the pattern transfer technique with no observable subsequent island growth on the terminated monolayer. (c) Further enhanced magnification of the area shown in (b) over which Raman and PL scans were taken. Note that the Raman/PL maps are shown at an orientation of 90° to this area. The red box shows the area corresponding to AFM scans. Scale bar is 9 µm (d) A1 exciton maximum photoluminescence map (e) B1 exciton maximum photoluminescence map (f) photoluminescence spectra at points 1 and 2 as indicated in (d), and the average spectrum over the entire scanned area, consisting of 14,400 individual point spectra. (g) Map of E' Raman peak sum (h) Map of A'1 Raman peak sum. Scale bar is 6 µm for all Raman and PL maps. (i) Average Raman spectrum over 14,400 points taken in the scanned area the film, showing a peak separation of 18 cm−1, which is in agreement with literature reports for monolayer MoS2.
Mentions: We have extended this growth procedure to the in-situ CVD patterning of MoS2 by pre-patterning the MoO3 seed layer before synthesis. This was done by sputtering MoO3 layers through a patterned metal shadow mask. This results in patterns of MoS2 monolayers that can be grown directly on a target substrate. The features demonstrated here are circles of closed MoS2 films with a diameter of approximately 100 μm as shown in Fig. 4(a). The resulting patterns are of approximately the same diameter as the original square patterns, with some loss of square structure due to the initial spread of material during sputtering, and then the subsequent evaporation into a vapour source followed by re-deposition as MoS2. This patterned growth is possible due to the close proximity of the oxide precursor. These patterned monolayers have the same high quality as the larger scale films as shown previously in Fig. 1(a). Although the resolution of the process is limited, as shown in Fig. 4(b), by a slight spread in growth, the method can produce multiple patterns without having to expose the monolayers to additional processing steps. This methodology could potentially be used to fabricate channels and other device components without the need for post growth processing steps.

Bottom Line: TMD monolayers were realized using a close proximity precursor supply in a CVD microreactor setup.A model describing the growth mechanism, which is capable of producing TMD monolayers on arbitrary substrates, is presented.Furthermore, through patterning of the precursor supply, we achieve patterned growth of monolayer TMDs in defined locations, which could be adapted for the facile production of electronic device components.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Chemistry, Trinity College Dublin, Dublin 2, Ireland [2] Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and Advanced Materials and BioEngineering Research (AMBER) Centre, Trinity College Dublin, Dublin 2, Ireland.

ABSTRACT
Reliable chemical vapour deposition (CVD) of transition metal dichalcogenides (TMDs) is currently a highly pressing research field, as numerous potential applications rely on the production of high quality films on a macroscopic scale. Here, we show the use of liquid phase exfoliated nanosheets and patterned sputter deposited layers as solid precursors for chemical vapour deposition. TMD monolayers were realized using a close proximity precursor supply in a CVD microreactor setup. A model describing the growth mechanism, which is capable of producing TMD monolayers on arbitrary substrates, is presented. Raman spectroscopy, photoluminescence, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy, scanning electron microscopy and electrical transport measurements reveal the high quality of the TMD samples produced. Furthermore, through patterning of the precursor supply, we achieve patterned growth of monolayer TMDs in defined locations, which could be adapted for the facile production of electronic device components.

No MeSH data available.


Related in: MedlinePlus