Sulfur vacancy-induced reversible doping of transition metal disulfides via hydrazine treatment

Chee, Sang Soo; Oh, Chohee; Son, Myungwoo; Son, Gi Cheol; Jang, Hwanchol; Yoo, Tae Jin; Lee, Seungmin; Lee, Wonki; Hwang, Jun Yeon; Choi, Hyunyong; Lee, Byoung Hun; Ham, Moon Ho

doi:10.1039/c7nr01883e

Cited by 68 publications

(68 citation statements)

References 41 publications

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“…The photoresponsivities of both MoS 2 devices also depended on the wavelength of visible light; photoresponsivity increased with decreasing the wavelength as more photogenerated carriers were produced in MoS 2 (Figure S14, Supporting Information). These behaviors have been commonly found in TMDC‐based photodetectors . In spite of similar trends of both devices, the photoresponsivities (390–2160 A W −1 ) of the devices with graphene/Ag contacts were higher than those (180–1040 A W −1 ) of the devices with Ag contacts at all power densities and wavelengths (Figure b; Figure S14, Supporting Information).…”

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confidence: 70%

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS₂ Field‐Effect Transistors

et al. 2018

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2D transition metal dichalcogenides (TMDCs) have emerged as promising candidates for post‐silicon nanoelectronics owing to their unique and outstanding semiconducting properties. However, contact engineering for these materials to create high‐performance devices while adapting for large‐area fabrication is still in its nascent stages. In this study, graphene/Ag contacts are introduced into MoS2 devices, for which a graphene film synthesized by chemical vapor deposition (CVD) is inserted between a CVD‐grown MoS2 film and a Ag electrode as an interfacial layer. The MoS2 field‐effect transistors with graphene/Ag contacts show improved electrical and photoelectrical properties, achieving a field‐effect mobility of 35 cm2 V−1 s−1, an on/off current ratio of 4 × 108, and a photoresponsivity of 2160 A W−1, compared to those of devices with conventional Ti/Au contacts. These improvements are attributed to the low work function of Ag and the tunability of graphene Fermi level; the n‐doping of Ag in graphene decreases its Fermi level, thereby reducing the Schottky barrier height and contact resistance between the MoS2 and electrodes. This demonstration of contact interface engineering with CVD‐grown MoS2 and graphene is a key step toward the practical application of atomically thin TMDC‐based devices with low‐resistance contacts for high‐performance large‐area electronics and optoelectronics.

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confidence: 70%

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS₂ Field‐Effect Transistors

et al. 2018

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“…After UV exposure in N 2 (UV‐N 2 ), the red‐shift of both

E_{2g}^{1}

and A 1g peaks are observed in the corresponding Raman spectrum (Figure b). Considering that the

E_{2g}^{1}

and A 1g modes are sensitive to the strain field and the charge effect, respectively, this result suggests that the UV irradiation under the highly pure nitrogen atmosphere induces tensile strain as well as photon‐assisted electron doping (i.e., n‐doping) in the MoS 2 monolayer . In the case of UV‐N 2 /O 2 , however, the change of the

E_{2g}^{1}

peak position is relatively small, and a blue‐shift is detected in the A 1g mode.…”

Section: Resultsmentioning

confidence: 88%

Atomic Vacancy Control and Elemental Substitution in a Monolayer Molybdenum Disulfide for High Performance Optoelectronic Device Arrays

Chee

Lee

et al. 2020

Adv Funct Materials

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Defect engineering of 2D transition metal dichalcogenides (TMDCs) is essential to modulate their optoelectrical functionalities, but there are only a few reports on defect‐engineered TMDC device arrays. Herein, the atomic vacancy control and elemental substitution in a chemical vapor deposition (CVD)‐grown molybdenum disulfide (MoS2) monolayer via mild photon irradiation under controlled atmospheres are reported. Raman spectroscopy, photoluminescence, X‐ray, and ultraviolet photoelectron spectroscopy comprehensively demonstrate that the well‐controlled photoactivation delicately modulates the sulfur‐to‐molybdenum ratio as well as the work function of a MoS2 monolayer. Furthermore, the atomic‐resolution scanning transmission electron microscopy directly confirms that small portions (2–4 at% corresponding to the defect density of 4.6 × 1012 to 9.2 × 1013 cm−2) of sulfur vacancies and oxygen substituents are generated in the MoS2 while the overall atomic‐scale structural integrity is well preserved. Electronic and optoelectronic device arrays are also realized using the defect‐engineered CVD‐grown MoS2, and it is further confirmed that the well‐defined sulfur vacancies and oxygen substituents effectively give rise to the selective n‐ and p‐doping in the MoS2, respectively, without the trade‐off in device performance. In particular, low‐percentage oxygen‐doped MoS2 devices show outstanding optoelectrical performance, achieving a detectivity of ≈1013 Jones and rise/decay times of 0.62 and 2.94 s, respectively.

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“…All of our devices exhibit typical n‐type characteristics, similar to most of previous literatures on MoS 2 devices. [ 29,30 ] A slight shift in threshold voltage ( V th ) gradually occurs toward positive gate voltage side, in accordance with the order of decreasing number of layers (trilayer → bilayer → monolayer). This reveals an effect of fluorine incorporation leading to p‐type doping effect.…”

Section: Figurementioning

confidence: 70%

Low‐Damaged Layer‐by‐Layer Etching of Large‐Area Molybdenum Disulfide Films via Mild Plasma Treatment

Chee

Ham

2020

Adv Materials Inter

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Controlling the number of layers of 2D transition metal dichalcogenide (TMDC) film is indispensable for optoelectronic applications because of their layer‐dependent optical features. However, most of methodologies on controlling TMDC layers induce undesirable defect formation and are performed on TMDC flakes, obtained from mechanical exfoliation. These limitations make practical TMDC‐based optoelectronic applications more difficult. Herein, layer‐by‐layer etching methodology of molybdenum disulfide (MoS2) films is developed using mild sulfur hexafluoride (SF6) plasma treatment. It is confirmed that the number of layers is successfully controlled from trilayer to monolayer by increasing plasma treatment time, while preserving overall film quality. Such low‐damaged layer‐by‐layer etching is attributed to this mild plasma etching system to only introduce the chemical reaction between ionized fluorine and MoS2, without physical damage to MoS2. Electrical properties of layer‐controlled MoS2 devices are also investigated, achieving comparatively high field‐effect mobilities of 16.2, 8.84, and 2.87 cm2 V−1 s−1 for tri‐, bi‐, and monolayer MoS2, respectively. This finding provides the possibility of realizing layer‐by‐layer engineering of 2D TMDCs.

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Sulfur vacancy-induced reversible doping of transition metal disulfides via hydrazine treatment

Cited by 68 publications

References 41 publications

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS₂ Field‐Effect Transistors

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS₂ Field‐Effect Transistors

Atomic Vacancy Control and Elemental Substitution in a Monolayer Molybdenum Disulfide for High Performance Optoelectronic Device Arrays

Low‐Damaged Layer‐by‐Layer Etching of Large‐Area Molybdenum Disulfide Films via Mild Plasma Treatment

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Sulfur vacancy-induced reversible doping of transition metal disulfides via hydrazine treatment

Cited by 68 publications

References 41 publications

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS2 Field‐Effect Transistors

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS2 Field‐Effect Transistors

Atomic Vacancy Control and Elemental Substitution in a Monolayer Molybdenum Disulfide for High Performance Optoelectronic Device Arrays

Low‐Damaged Layer‐by‐Layer Etching of Large‐Area Molybdenum Disulfide Films via Mild Plasma Treatment

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Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS₂ Field‐Effect Transistors

Lowering the Schottky Barrier Height by Graphene/Ag Electrodes for High‐Mobility MoS₂ Field‐Effect Transistors