Microscopic basis for the band engineering of Mo1−xWxS2-based heterojunction

Yoshida, Shoji; Kobayashi, Yu; Sakurada, Ryuji; Mori, Shohei; Miyata, Yasumitsu; Mogi, Hiroyuki; Koyama, Toshie; Takeuchi, Osamu; Shigekawa, Hidemi

doi:10.1038/srep14808

Cited by 53 publications

(74 citation statements)

References 28 publications

(44 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a result, a number of successful strategies for doping 2D materials have been developed, including direct charge injection via electrostatic gating, [222][223][224][225] charge donation from physically or chemically adsorbed molecules or ions, [226][227][228][229][230][231] and covalent bonding 232,233 via edge functionalization or substituted atoms. [4][5][6][7][8][234][235][236][237][238] These doping methods impact the optical, electrical, and optoelectronic properties of 2D TMDs. For examples, physisorbed or chemisorbed molecules on 2D layers act as molecular gates by injecting charge, which can modulate PL intensity through different charge carrier polarity.…”

Section: Doping and Alloyingmentioning

confidence: 99%

A roadmap for electronic grade 2D materials

et al. 2019

View full text Add to dashboard Cite

Since their modern debut in 2004, 2-dimensional (2D) materials continue to exhibit scientific and industrial promise, providing a broad materials platform for scientific investigation, and development of nano-and atomic-scale devices. A significant focus of the last decade's research in this field has been 2D semiconductors, whose electronic properties can be tuned through manipulation of dimensionality, substrate engineering, strain, and doping. 1-8 2D semiconductors such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) have dominated recent interest for potential integration in electronic technologies, due to their intrinsic and tunable properties, atomic-scale thicknesses, and relative ease of stacking to create new and custom structures. However, to go "beyond the bench", advances in large-scale, 2D layer synthesis and engineering must lead to "exfoliation-quality" 2D layers at the wafer scale. This roadmap aims to address this grand challenge by identifying key technology drivers where 2D layers can have an impact, and to discuss synthesis and layer engineering for the realization of electronic-grade, 2D materials. We focus on three fundamental areas of research that must be heavily pursued in both experiment and computation to achieve high-quality materials for electronic and optoelectronic applications. The document is organized as follows:

show abstract

Section: Doping and Alloyingmentioning

confidence: 99%

A roadmap for electronic grade 2D materials

et al. 2019

View full text Add to dashboard Cite

show abstract

“…As an impurity, Mo atoms are well studied and cause bandgap narrowing through the substitution of W sites in monolayer WS 2 . 14,15,23,24) However, there are very few studies on the doping of other transition metals for monolayer TMDCs. In the present study, Nb is selected because its atomic size is comparable to that of Mo and it is reported to generate acceptor states for some TMDCs.…”

mentioning

confidence: 99%

“…These results are similar WS 2 growth by halide-assisted CVD reported previously. 21) For structural characterization, we conducted annular dark field (ADF)-STEM observations of a monolayer sample 13,14,23) It should be noted that the STEM images of the doped samples are different from those of pure WS 2 monolayers as observed previously. 14) Through a statistical analysis of the ADF-STEM images obtained at six different positions of the same grain, the ratio of dark spots is estimated to be 0.55 ± 0.03%.…”

mentioning

confidence: 99%

Growth and optical properties of Nb-doped WS₂ monolayers

Sasaki

Kobayashi

Liu³

et al. 2016

Appl. Phys. Express

Self Cite

View full text Add to dashboard Cite

We report the chemical vapor deposition growth of Nb-doped WS 2 monolayers and their characterization. Electron microscopy observations reveal that the Nb atom was substituted at the W site at a rate of approximately 0.5%. Unlike Mo doping, Nb-doped samples have photoluminescence (PL) peaks at 1.4-1.6 eV at room temperature. The peak energies are lower than the optical bandgap of 1.8 eV, and a saturation behavior of PL intensity is observed with the increase in excitation power. These results indicate that the observed PL peaks are assignable to the emission from impurity states generated by the substitution of Nb. © 2016 The Japan Society of Applied Physics T he optical properties of atomic-layer transition metal dichalcogenides (TMDCs) have recently attracted much attention owing to their wide-range bandgap energies from visible to infrared, 1-3) unique phenomena related to spin-valley physics, 4,5) and single-photon emission. [6][7][8][9] In particular, defect-derived excitonic states have recently received much attention for their applications in single-photon emitters. To date, several groups have reported that atomic-layer TMDCs show photoluminescence (PL) from optically active defects at low temperature (4 ∼ 90 K). 6-11) Such a two-dimensional (2D) single-quantum emission has practical advantages in efficient photon extraction and high integration capability. However, the details of such defect sites are still unclear, and PL can generally be observed only at low temperature. These issues may be resolved by the controlled fabrication of defect states, which is an important challenge in understanding and using TMDC atomic layers as quantum light sources.In general, defect states in low-dimensional materials are created through several mechanisms, including atomic vacancy formation, 12) impurity doping, [13][14][15][16] and chemical functionalization. 17) In this study, we have investigated impuritydoped WS 2 monolayers as a model system. Monolayer WS 2 is a semiconductor with a relatively wide direct bandgap and high air stability, and there have been many reports on its growth process and characterization. 10,[18][19][20][21][22] To implant impurities in WS 2 , we employed halide-assisted chemical vapor deposition (CVD), which was recently developed by Li et al. 21) This method can produce large-area monolayer WS 2 at relatively low temperatures (700°C) and under atmospheric pressure. Importantly, the use of halides can effectively transport precursors of transition metals, which usually have very low vapor pressure. As an impurity, Mo atoms are well studied and cause bandgap narrowing through the substitution of W sites in monolayer WS 2 . 14,15,23,24) However, there are very few studies on the doping of other transition metals for monolayer TMDCs. In the present study, Nb is selected because its atomic size is comparable to that of Mo and it is reported to generate acceptor states for some TMDCs. 16,25) Here, we report the synthesis and characterization of monolayer impurity-doped WS 2 using halide-ass...

show abstract

“…Clean and sharp lateral interfaces in TMD HSs were reported in 2014 by three groups [30,31,32], improving on previous alloy growth M (1) X (1) x − M (2) X (2) 1−x [51,52,53,54,55,56,57] with different metal M (j) and chalcogen X (j) combinations. Recent experiments have shown successful growth of longer interfacial sections with great strain, geometry, and/or electronic band alignment tunability [37,38,36].…”

Section: Methodsmentioning

confidence: 76%

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

Ávalos-Ovando

Mastrogiuseppe

Ulloa

2019

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The growth and exfoliation of two-dimensional (2D) materials have led to the creation of edges and novel interfacial states at the juncture between crystals with different composition or phases. These hybrid heterostructures (HSs) can be built as vertical van der Waals stacks, resulting in a 2D interface, or as stitched adjacent monolayer crystals, resulting in one-dimensional (1D) interfaces. Although most attention has been focused on vertical HSs, increasing theoretical and experimental interest in 1D interfaces is evident. In-plane interfacial states between different 2D materials inherit properties from both crystals, giving rise to robust states with unique 1D non-parabolic dispersion and strong spinorbit effects. With such unique characteristics, these states provide an exciting platform for realizing 1D physics. Here, we review and discuss advances in 1D heterojunctions, with emphasis on theoretical approaches for describing those between semiconducting transition metal dichalcogenides M X 2 (with M =Mo, W and X= S, Se, Te), and how the interfacial states can be characterized and utilized. We also address how the interfaces depend on edge geometries (such as zigzag and armchair) or strain, as lattice parameters differ across the interface, and how these features affect excitonic/optical response. This review is intended to serve as a resource for promoting theoretical and experimental studies in this rapidly evolving field.

show abstract

Microscopic basis for the band engineering of Mo1−xWxS2-based heterojunction

Cited by 53 publications

References 28 publications

A roadmap for electronic grade 2D materials

A roadmap for electronic grade 2D materials

Growth and optical properties of Nb-doped WS₂ monolayers

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

Contact Info

Product

Resources

About

Microscopic basis for the band engineering of Mo1−xWxS2-based heterojunction

Cited by 53 publications

References 28 publications

A roadmap for electronic grade 2D materials

A roadmap for electronic grade 2D materials

Growth and optical properties of Nb-doped WS2 monolayers

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

Contact Info

Product

Resources

About

Growth and optical properties of Nb-doped WS₂ monolayers