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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.


(a) Two terminal Ids-Vds characteristics of the device for Vgs = 0. (b) Transfer characteristics (Ids vs Vg) of the device recorded for varying values of Vds. (c) Transfer characteristics from (b) plotted on a logarithmic curve.
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f3: (a) Two terminal Ids-Vds characteristics of the device for Vgs = 0. (b) Transfer characteristics (Ids vs Vg) of the device recorded for varying values of Vds. (c) Transfer characteristics from (b) plotted on a logarithmic curve.

Mentions: Electrical transport measurements were performed across large channel areas that consisted of multiple grains. A field effect transistor was fabricated as described in section S3 of the Supporting Information. Fig. 3(a) shows drain current vs. drain voltage (Ids vs. Vds) characteristics of the device from a two-terminal measurement with no applied back gate voltage, i.e. Vgs = 0 V. Slightly asymmetric contacts can be observed from the source-drain electrodes, which can be attributed to the presence of contact resistance. Fig. 3(b) shows the transfer characteristics (Ids vs Vgs) of the device for different source-drain voltages ranging from 0.5 to 2 V in increments of 0.5 V. The transfer curve shows strong n-type behaviour, and the current on/off ratio exceeds 103 for all values of source-drain voltage. Furthermore, the off-state of the device has the same level for all the applied source-drain voltages, as shown in Fig. 3(c), meaning distinct on/off states can be observed. The field-effect mobility was estimated from equation (1): where L is the channel length (~ 17.5 μm), W is the channel width (~ 145 μm), Cox is the gate capacitance (~ 11.5 nF), and Vds is the source-drain voltage. The maximum value of the slope, dIds/dVds, was used for calculations. For a bias voltage of 2 V, the field-effect mobility was estimated to be approximately 1.15 cm2 V−1 s−1, which is in line with or superior to values previously reported for both CVD MoS2365051 and mechanically exfoliated MoS2, in the absence of high-k dielectric encapsulation layers752. This is an important result as it shows that large area CVD grown MoS2 is potentially viable for electronic devices despite the presence of grain boundaries.


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) Two terminal Ids-Vds characteristics of the device for Vgs = 0. (b) Transfer characteristics (Ids vs Vg) of the device recorded for varying values of Vds. (c) Transfer characteristics from (b) plotted on a logarithmic curve.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: (a) Two terminal Ids-Vds characteristics of the device for Vgs = 0. (b) Transfer characteristics (Ids vs Vg) of the device recorded for varying values of Vds. (c) Transfer characteristics from (b) plotted on a logarithmic curve.
Mentions: Electrical transport measurements were performed across large channel areas that consisted of multiple grains. A field effect transistor was fabricated as described in section S3 of the Supporting Information. Fig. 3(a) shows drain current vs. drain voltage (Ids vs. Vds) characteristics of the device from a two-terminal measurement with no applied back gate voltage, i.e. Vgs = 0 V. Slightly asymmetric contacts can be observed from the source-drain electrodes, which can be attributed to the presence of contact resistance. Fig. 3(b) shows the transfer characteristics (Ids vs Vgs) of the device for different source-drain voltages ranging from 0.5 to 2 V in increments of 0.5 V. The transfer curve shows strong n-type behaviour, and the current on/off ratio exceeds 103 for all values of source-drain voltage. Furthermore, the off-state of the device has the same level for all the applied source-drain voltages, as shown in Fig. 3(c), meaning distinct on/off states can be observed. The field-effect mobility was estimated from equation (1): where L is the channel length (~ 17.5 μm), W is the channel width (~ 145 μm), Cox is the gate capacitance (~ 11.5 nF), and Vds is the source-drain voltage. The maximum value of the slope, dIds/dVds, was used for calculations. For a bias voltage of 2 V, the field-effect mobility was estimated to be approximately 1.15 cm2 V−1 s−1, which is in line with or superior to values previously reported for both CVD MoS2365051 and mechanically exfoliated MoS2, in the absence of high-k dielectric encapsulation layers752. This is an important result as it shows that large area CVD grown MoS2 is potentially viable for electronic devices despite the presence of grain boundaries.

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.