Substrate-directed synthesis of MoS2 nanocrystals with tunable dimensionality and optical properties

Chowdhury, Tomojit; Kim, Jungkil; Sadler, Erick C.; Li, Chenyang; Lee, Seong Won; Jo, Kiyoung; Xu, Weinan; Gracias, David H.; Drichko, Natalia; Jariwala, Deep; Brintlinger, Todd; Mueller, Tim; Park, Hong Gyu; Kempa, Thomas J.

doi:10.1038/s41565-019-0571-2

Cited by 104 publications

(133 citation statements)

References 48 publications

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“…Interestingly, we found the PL intensity at the edge and grain boundary are much stronger than that at the basal plane. The large variations in PL of edges vs basal plane regions have been made previously in both CVD grown and exfoliated flakes, and many explanations have been pointed out for this including presence of oxidation of the edge site 31,32,47 to local disorder to potential confinement of excitations near the edge. However, these results are not sufficient to explain this solely by oxidation or due to the structural and electronic property difference between basal plane and the edge.…”

Section: Correlation Of Nanoscale Features Using Tip-enhanced Photolumentioning

confidence: 77%

“…For example, it was recently reported that an energetically disordering nanoscale region of~300 nm width is present at the edges and grain boundaries in CVD grown MoS 2 , where the spectral median is blue shifted compared to basal plane "bulk" regions 31 . In another report, 1D MoS 2 nanoribbons were synthesized and were found to emit at higher energies (blue shifted) as compared to 2D MoS 2 when measured via TEPL 32 . In these bottom up synthesized MoS 2 nanoribbons, the near field photoluminescence was measured in <200 nm width regions which fall entirely in the edge-boundary disordered PL quenched region as discussed above report.…”

Section: Introductionmentioning

confidence: 94%

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Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

Moore

Nguyen

et al. 2020

npj 2D Mater Appl

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Developing characterization strategies to better understand nanoscale features in two-dimensional nanomaterials is of crucial importance, as the properties of these materials are many times driven by nanoscale and microscale chemical and structural modifications within the material. For the case of large area monolayer MoSe2 flakes, kelvin probe force microscopy coupled with tip-enhanced photoluminescence was utilized to evaluate such features including internal grain boundaries, edge effects, bilayer contributions, and effects of oxidation/aging, many of which are invisible to topographical mapping. A reduction in surface potential due to n-type behavior was observed at the edge of the flakes as well as near grain boundaries. Potential phase mapping, which corresponds to the local dielectric constant, depicted local biexciton and trion states in optically-active regions of interest such as grain boundaries. Finally, nanoscale surface potential and photoluminescence mapping was performed at several stages of oxidation, revealing that various oxidative states can be evaluated during the aging process. Importantly, all of the characterization performed in this study was non-destructive and rapid, crucial for quality evaluation of an exciting class of two-dimensional nanomaterials.

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Section: Correlation Of Nanoscale Features Using Tip-enhanced Photolumentioning

confidence: 77%

Section: Introductionmentioning

confidence: 94%

Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

Moore

Nguyen

et al. 2020

npj 2D Mater Appl

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“…In this regard, the anisotropic substrate induces symmetry breaking of incipient MoS 2 seed and enables rapid crystal growth in one direction owing to the highly asymmetric energy landscape experienced by the MoS 2 crystal. [ 45 ] In experiment, we just found the well‐aligned MoS 2 grains grown at high temperature, which are proved to have relative strong interaction with substrate, can grow into the rectangle shape. This is reasonable because the strong van der Waals interaction together with the anisotropic substrate structure could passivate the growth of MoS 2 along the [0001] crystallographic direction of substrate, while allowing its 1D growth along [1‐100] crystallographic direction of substrate.…”

Section: Figurementioning

confidence: 99%

Epitaxial Growth of Rectangle Shape MoS₂ with Highly Aligned Orientation on Twofold Symmetry a‐Plane Sapphire

Wang

Deng

et al. 2020

Small

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2D transition-metal dichalcogenides (TMDs) are an emerging class of materials with superior properties that make them highly attractive for fundamental studies of novel physics and for applications ranging from nanoelectronics and nanophotonics to sensing and catalysis. [1][2][3][4][5] As the most extensively Research on transition metal dichalcogenides (TMDs) has been accelerated by the development of large-scale synthesis based on chemical vapor deposition (CVD) growth. However, in most cases, CVD-grown TMDs are composed of randomly oriented grains, and thus contain many distorted grain boundaries (GBs), which seriously degrade their electrical and photoelectrical properties. Here, the epitaxial growth of highly aligned MoS 2 grains is reported on a twofold symmetry a-plane sapphire substrate. The obtained MoS 2 grains have an unusual rectangle shape with perfect orientation alignment along the [1-100] crystallographic direction of a-plane sapphire. It is found that the growth temperature plays a key role in its orientation alignment and morphology evolution, and high temperature is beneficial to the initial MoS 2 seeds rotate to the favorable orientation configurations. In addition, the photoluminescence quenching of the well-aligned MoS 2 grains indicates a strong MoS 2 −substrate interaction which induces the anisotropic growth of MoS 2 , and thus brings the formation of rectangle shape grains. Moreover, the well-aligned MoS 2 grains splice together without GB formation, and thus that has negligible effect on its electrical transport properties. The progress achieved in this work could promote the controlled synthesis of large-area TMDs single crystal film and the scalable fabrication of high-performance electronic devices.

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“…Only in a very recent report has it been shown that the dimensionality of thin MoS 2 nanoribbons could be tuned when it is grown on phosphine pre‐treated Si(001) surfaces. [ 7 ] The nanoribbons are fabricated with a yield of 75%, mixed with triangle nanosheets, and they exhibited optical properties that depended on their dimensionality. The as‐obtained MoS 2 nanoribbons are attached to the substrate in random positions and orientations.…”

Section: Figurementioning

confidence: 99%

“…[5] Moreover, sizedependent effects, have been found when modulating dimensions of MoS 2 nanostructures. [6,7] Indeed, MoS 2 emerges as a highly promising material that may impact many research fields, including electronics, [8] catalysis, [9] energy storage, [10] water treatment, [11] and gas sensing. [12] To realize the full potential of MoS 2 , the first task is to find a convenient and robust means to scalably fabricate MoS 2 with controllable dimensions.…”

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confidence: 99%

Scalable Fabrication of Molybdenum Disulfide Nanostructures and their Assembly

Huang

Kang

et al. 2020

Advanced Materials

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Transition metal dichalcogenides (TMD) have attracted immense research interest owing to their 2D stacking molecular structures and the resulted chemical and physical properties. [1] Among various TMD materials, single-crystal molybdenum disulfide (MoS 2) nanoflakes in the 2H-phase, which constitute the basic unit of various crystalline MoS 2 nanostructures and bulk MoS 2 , possess edge sites and in plane sulfur vacancies which for instance show outstanding catalytic activity with an ultralow hydrogen adsorption Gibbs free energy-similar to that of the most efficient platinum and other noble metals. [2] However, in contrast to platinum, MoS 2 is much cheaper, and because it is a semiconductor, its electric conductivity can be readily tuned by the application of a voltage or light. This has been exploited in a variety of applications. For instance, MoS 2 has been demonstrated as an optical and biochemical sensor material. [3] MoS 2 fieldeffect transistors exhibit an on/off ratio as high as ≈10 8 and near-ideal subthreshold Molybdenum disulfide (MoS 2) is a multifunctional material that can be used for various applications. In the single-crystalline form, MoS 2 shows superior electronic properties. It is also an exceptionally useful nanomaterial in its polycrystalline form with applications in catalysis, energy storage, water treatment, and gas sensing. Here, the scalable fabrication of longitudinal MoS 2 nanostructures, i.e., nanoribbons, and their oxide hybrids with tunable dimensions in a rational and well-reproducible fashion, is reported. The nano ribbons, obtained at different reaction stages, that is, MoO 3 , MoS 2 /MoO 2 hybrid, and MoS 2 , are fully characterized. The growth method presented herein has a high yield and is particularly robust. The MoS 2 nanoribbons can readily be removed from its substrate and dispersed in solution. It is shown that functionalized MoS 2 nanoribbons can be manipulated in solution and assembled in controlled patterns and directly on microelectrodes with UV-click-chemistry. Owing to the high chemical purity and polycrystalline nature, the MoS 2 nanostructures demonstrate rapid optoelectronic response to wavelengths from 450 to 750 nm, and successfully remove mercury contaminants from water. The scalable fabrication and manipulation followed by light-directed assembly of MoS 2 nanoribbons, and their unique properties, will be inspiring for device fabrication and applications of the transition metal dichalcogenides.

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Substrate-directed synthesis of MoS2 nanocrystals with tunable dimensionality and optical properties

Cited by 104 publications

References 48 publications

Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

Epitaxial Growth of Rectangle Shape MoS₂ with Highly Aligned Orientation on Twofold Symmetry a‐Plane Sapphire

Scalable Fabrication of Molybdenum Disulfide Nanostructures and their Assembly

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Substrate-directed synthesis of MoS2 nanocrystals with tunable dimensionality and optical properties

Cited by 104 publications

References 48 publications

Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

Uncovering topographically hidden features in 2D MoSe2 with correlated potential and optical nanoprobes

Epitaxial Growth of Rectangle Shape MoS2 with Highly Aligned Orientation on Twofold Symmetry a‐Plane Sapphire

Scalable Fabrication of Molybdenum Disulfide Nanostructures and their Assembly

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Epitaxial Growth of Rectangle Shape MoS₂ with Highly Aligned Orientation on Twofold Symmetry a‐Plane Sapphire