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Controllable synthesis of molybdenum tungsten disulfide alloy for vertically composition-controlled multilayer.

Song JG, Ryu GH, Lee SJ, Sim S, Lee CW, Choi T, Jung H, Kim Y, Lee Z, Myoung JM, Dussarrat C, Lansalot-Matras C, Park J, Choi H, Kim H - Nat Commun (2015)

Bottom Line: The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap.Various spectroscopic and microscopic results indicate that the synthesized Mo1-xWxS2 alloys have complete mixing of Mo and W atoms and tunable band gap by systematically controlled composition and layer number.Further, we demonstrate that a VCC Mo1-xWxS2 multilayer photodetector generates three to four times greater photocurrent than MoS2- and WS2-based devices, owing to the broadband light absorption.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.

ABSTRACT
The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap. Here we show a synthesis process for Mo1-xWxS2 alloy using sulfurization of super-cycle atomic layer deposition Mo1-xWxOy. Various spectroscopic and microscopic results indicate that the synthesized Mo1-xWxS2 alloys have complete mixing of Mo and W atoms and tunable band gap by systematically controlled composition and layer number. Based on this, we synthesize a vertically composition-controlled (VCC) Mo1-xWxS2 multilayer using five continuous super-cycles with different cycle ratios for each super-cycle. Angle-resolved X-ray photoemission spectroscopy, Raman and ultraviolet-visible spectrophotometer results reveal that a VCC Mo1-xWxS2 multilayer has different vertical composition and broadband light absorption with strong interlayer coupling within a VCC Mo1-xWxS2 multilayer. Further, we demonstrate that a VCC Mo1-xWxS2 multilayer photodetector generates three to four times greater photocurrent than MoS2- and WS2-based devices, owing to the broadband light absorption.

No MeSH data available.


Characterization of VCC Mo1−xWxS2 multilayer.(a) Sequential super-cycle ALD procedure and schematic structure of a VCC Mo1−xWxS2 multilayer. (b) AFM image and (c) height profiles (along with white dashed line in AFM image) for a VCC Mo1−xWxS2 multilayer. Scale bars, 0.5 μm. (d) Calculated atomic concentration and relative concentration ratio of Mo and W from ARXPS measurement. (e) Raman spectra for a VCC Mo1−xWxS2 multilayer. (f) Raman peak position of A1g and MoS2-like E12g modes from fitted Raman spectra (red and blue solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line). (g) Calculated Raman peak distances between A1g and MoS2-like E12g modes from fitted Raman spectra (red solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line).
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f6: Characterization of VCC Mo1−xWxS2 multilayer.(a) Sequential super-cycle ALD procedure and schematic structure of a VCC Mo1−xWxS2 multilayer. (b) AFM image and (c) height profiles (along with white dashed line in AFM image) for a VCC Mo1−xWxS2 multilayer. Scale bars, 0.5 μm. (d) Calculated atomic concentration and relative concentration ratio of Mo and W from ARXPS measurement. (e) Raman spectra for a VCC Mo1−xWxS2 multilayer. (f) Raman peak position of A1g and MoS2-like E12g modes from fitted Raman spectra (red and blue solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line). (g) Calculated Raman peak distances between A1g and MoS2-like E12g modes from fitted Raman spectra (red solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line).

Mentions: The composition controllability of our ALD-based Mo1−xWxS2 alloy synthesis process enables synthesis of a VCC Mo1−xWxS2 multilayer with a clean interface, strong interlayer coupling and broadband light absorption. We sulfurized a VCC Mo1−xWxOy thin film that was deposited by a sequential super-cycle ALD process, so as to synthesize a VCC Mo1−xWxS2 multilayer, as shown in Fig. 6a. First, we conducted 20 cycles of WO3 ALD on a SiO2 substrate, corresponding to 1l WS2. We immediately performed three super-cycles of Mo1−xWxOy ALD with different super-cycle n and m numbers, in the following order: n=1 and m=6, n=2 and m=4, and n=3 and m=1. Last, we conducted three cycles of MoOx ALD (n=3) corresponding to 1l MoS2. The deposited VCC Mo1−xWxOy thin film was sulfurized to convert it into a VCC Mo1−xWxS2 multilayer. Figure 6b,c shows an AFM image and height profile of the transferred VCC Mo1−xWxS2 multilayer, with a measured thickness of ∼3.5 nm. This thickness, synthesized by five sequential ALD super-cycles, corresponds to a 5l Mo1−xWxS2 alloy, which is consistent with each super-cycle result for the 1l Mo1−xWxS2 alloy.


Controllable synthesis of molybdenum tungsten disulfide alloy for vertically composition-controlled multilayer.

Song JG, Ryu GH, Lee SJ, Sim S, Lee CW, Choi T, Jung H, Kim Y, Lee Z, Myoung JM, Dussarrat C, Lansalot-Matras C, Park J, Choi H, Kim H - Nat Commun (2015)

Characterization of VCC Mo1−xWxS2 multilayer.(a) Sequential super-cycle ALD procedure and schematic structure of a VCC Mo1−xWxS2 multilayer. (b) AFM image and (c) height profiles (along with white dashed line in AFM image) for a VCC Mo1−xWxS2 multilayer. Scale bars, 0.5 μm. (d) Calculated atomic concentration and relative concentration ratio of Mo and W from ARXPS measurement. (e) Raman spectra for a VCC Mo1−xWxS2 multilayer. (f) Raman peak position of A1g and MoS2-like E12g modes from fitted Raman spectra (red and blue solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line). (g) Calculated Raman peak distances between A1g and MoS2-like E12g modes from fitted Raman spectra (red solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line).
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Related In: Results  -  Collection

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f6: Characterization of VCC Mo1−xWxS2 multilayer.(a) Sequential super-cycle ALD procedure and schematic structure of a VCC Mo1−xWxS2 multilayer. (b) AFM image and (c) height profiles (along with white dashed line in AFM image) for a VCC Mo1−xWxS2 multilayer. Scale bars, 0.5 μm. (d) Calculated atomic concentration and relative concentration ratio of Mo and W from ARXPS measurement. (e) Raman spectra for a VCC Mo1−xWxS2 multilayer. (f) Raman peak position of A1g and MoS2-like E12g modes from fitted Raman spectra (red and blue solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line). (g) Calculated Raman peak distances between A1g and MoS2-like E12g modes from fitted Raman spectra (red solid line) and from measured Raman spectra of 1l Mo1−xWxS2 alloy (black dashed line).
Mentions: The composition controllability of our ALD-based Mo1−xWxS2 alloy synthesis process enables synthesis of a VCC Mo1−xWxS2 multilayer with a clean interface, strong interlayer coupling and broadband light absorption. We sulfurized a VCC Mo1−xWxOy thin film that was deposited by a sequential super-cycle ALD process, so as to synthesize a VCC Mo1−xWxS2 multilayer, as shown in Fig. 6a. First, we conducted 20 cycles of WO3 ALD on a SiO2 substrate, corresponding to 1l WS2. We immediately performed three super-cycles of Mo1−xWxOy ALD with different super-cycle n and m numbers, in the following order: n=1 and m=6, n=2 and m=4, and n=3 and m=1. Last, we conducted three cycles of MoOx ALD (n=3) corresponding to 1l MoS2. The deposited VCC Mo1−xWxOy thin film was sulfurized to convert it into a VCC Mo1−xWxS2 multilayer. Figure 6b,c shows an AFM image and height profile of the transferred VCC Mo1−xWxS2 multilayer, with a measured thickness of ∼3.5 nm. This thickness, synthesized by five sequential ALD super-cycles, corresponds to a 5l Mo1−xWxS2 alloy, which is consistent with each super-cycle result for the 1l Mo1−xWxS2 alloy.

Bottom Line: The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap.Various spectroscopic and microscopic results indicate that the synthesized Mo1-xWxS2 alloys have complete mixing of Mo and W atoms and tunable band gap by systematically controlled composition and layer number.Further, we demonstrate that a VCC Mo1-xWxS2 multilayer photodetector generates three to four times greater photocurrent than MoS2- and WS2-based devices, owing to the broadband light absorption.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.

ABSTRACT
The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap. Here we show a synthesis process for Mo1-xWxS2 alloy using sulfurization of super-cycle atomic layer deposition Mo1-xWxOy. Various spectroscopic and microscopic results indicate that the synthesized Mo1-xWxS2 alloys have complete mixing of Mo and W atoms and tunable band gap by systematically controlled composition and layer number. Based on this, we synthesize a vertically composition-controlled (VCC) Mo1-xWxS2 multilayer using five continuous super-cycles with different cycle ratios for each super-cycle. Angle-resolved X-ray photoemission spectroscopy, Raman and ultraviolet-visible spectrophotometer results reveal that a VCC Mo1-xWxS2 multilayer has different vertical composition and broadband light absorption with strong interlayer coupling within a VCC Mo1-xWxS2 multilayer. Further, we demonstrate that a VCC Mo1-xWxS2 multilayer photodetector generates three to four times greater photocurrent than MoS2- and WS2-based devices, owing to the broadband light absorption.

No MeSH data available.