Electrical and optical properties of transition metal dichalcogenides on talc dielectrics

Nutting, Darren; Prando, Gabriela Augusta; Severijnen, Marion E.; Barcelos, Ingrid D.; Guo, Shi; Christianen, Peter C. M.; Zeitler, U.; Gobato, Y. Galvão; Withers, Freddie

doi:10.1039/d1nr04723j

Cited by 18 publications

(20 citation statements)

References 60 publications

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“…A similar result is expected for ML TMD-talc heterostructures. Actually, we have observed recently that TMD-talc FET devices with a layer thickness below 40 nm are slightly more p type than MoS 2 and MoSe 2 transistors on h-BN or SiO 2 dielectrics [22]. We anticipate that the FWHM of the X emission of WS 2 -talc can be further reduced by using an appropriate thermal treatment, such as the standard procedures used for h-BN-encapsulated TMD monolayers [29].…”

Section: Resultsmentioning

confidence: 97%

“…The PL spectra are normalized to the intensity of the X peak. The PL spectra of the WS 2 -talc sample are stable [22], and no photodoping effect [24] is observed. Figure S1 within the Supplemental Material [25] shows in more detail the spectra for different laser powers.…”

Section: Resultsmentioning

confidence: 99%

“…More recently, it was observed that MoS 2 -talc samples with a talc thickness of 30 nm presented an enhancement in the PL intensity and a reduced PL linewidth (40-45 meV, depending on the laser position) at 300 K, as compared to MoS 2 /SiO 2 (50-80 meV) [21]. It is also shown that talc is a promising dielectric for 2D devices [22]. However, there are no previous detailed studies of PL and magneto-PL of ML TMD-talc at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Revealing Excitonic Complexes in Monolayer WS2 on Talc Dielectric

et al. 2021

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We report on a detailed study of low-temperature photoluminescence (PL) and magnetophotoluminescence under perpendicular magnetic fields (up to 30 T) and circularly polarized excitation on high-quality monolayer (ML) WS 2 on a thick layer (120 nm) of talc dielectric. Remarkably, we obtained high-quality samples without any evidence of localized exciton emission at low temperature and a PL linewidth comparable to that of WS 2 /h-BN samples. As a consequence, we observe well-resolved emission peaks at low temperature due to the formation of excitonic complexes, including a dark-trion (DT) state and phonon replicas of the DT without the application of an in-plane magnetic field. The nature of the emission peaks, the magnetic field dependence of the degree of polarization, and g factors are discussed in detail and compared with the corresponding results obtained for h-BN encapsulated transition-metal dichalcogenide (TMD) samples. We observe that under σ + -polarized excitation the sign of the circular polarization of biexcitons is reversed under higher magnetic fields. In addition, the dark-trion polarization increases considerably with increasing perpendicular magnetic field, demonstrating different behavior compared with previous studies of dark trions on monolayer WSe 2 . Our results suggest that talc is indeed a promising layered material for the surface protection of ML TMDs and to explore fundamental physics in view of applications in optoelectronic devices.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Revealing Excitonic Complexes in Monolayer WS2 on Talc Dielectric

et al. 2021

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“…Layered materials (LMs) possess exquisite electrical, optical, and mechanical properties that have been predicted theoretically − and measured experimentally by Raman spectroscopy, − infrared spectroscopy, − and other analytical techniques. − The potential use of LMs as building blocks for future ultrathin and flexible devices , has created interest from both scientific and economic perspectives to search for and characterize LMs that are easily obtained in nature. − Talc, also known as soapstone, is an abundant, naturally occurring magnesium hydrosilicate mineral from the phyllosilicate group and is the softest known mineral . It is an electrical insulator (bandgap of ∼5 eV) , and allows for excellent basal cleavage, with layers held together by van der Waals forces, , making it an excellent target for future low-cost optoelectronic applications. Figure a–c presents the optical images of the bulk crystal (mineral “block”); an ultrathin staircase-like exfoliated sample of natural talc; and the schematic crystalline structure, respectively.…”

Section: Introductionmentioning

confidence: 99%

Raman and Far-Infrared Synchrotron Nanospectroscopy of Layered Crystalline Talc: Vibrational Properties, Interlayer Coupling, and Symmetry Crossover

et al. 2023

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Talc is an insulating layered material that is stable at ambient conditions and has high-quality basal cleavage, which is a major advantage for its use in van der Waals heterostructures. Here, we use near-field synchrotron infrared nanospectroscopy, Raman spectroscopy, and first-principles calculations to investigate the structural and vibrational properties of talc crystals, ranging from monolayer to bulk, in the 300–750 and <60 cm–1 spectral windows. We observe a symmetry crossover from mono to bilayer talc samples, attributed to the stacking of adjacent layers. The in-plane lattice parameters and frequencies of intralayer modes of talc display weak dependence on the number of layers, consistent with a weak interlayer interaction. On the other hand, the low-frequency (<60 cm–1) rigid-layer (interlayer) modes of talc are suitable to identify the number of layers in ultrathin talc samples, besides revealing strong in-plane and out-of-plane anisotropy in the interlayer force constants and related elastic stiffnesses of single crystals. The shear and breathing force constants of talc are found to be 66 and 28%, respectively, lower than those of graphite, making talc an excellent lubricant that can be easily exfoliated. Our results broaden the understanding of the structural and vibrational properties of talc at the nanoscale regime and serve as a guide for future ultrathin heterostructures applications.

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“…They can be point defects (vacancies, substitutional or interstitial impurities) or extended defects (grain boundaries, twin planes and stacking faults), strongly affecting the optoelectronic responses of the nanomaterial. Nevertheless, a deeper knowledge of such impurities and defects is essential to identify their eventual influence on a given property allowing their manipulation and tailoring to specific 2D technological applications, such as sensors [18,26,27], electronic devices [9,12,17,[22][23][24]28] and catalysts [29,30].…”

Section: Introductionmentioning

confidence: 99%

High throughput investigation of an emergent and naturally abundant 2D material: Clinochlore

Oliveira

Guallichico

Policarpo

et al. 2022

Applied Surface Science

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Electrical and optical properties of transition metal dichalcogenides on talc dielectrics

Abstract: Advanced van der Waals (vdW) heterostructure devices rely on the incorporation of high quality dielectric materials which need to possess a low defect density as well as being atomically smooth...

Cited by 18 publications

References 60 publications

Revealing Excitonic Complexes in Monolayer WS2 on Talc Dielectric

Revealing Excitonic Complexes in Monolayer WS2 on Talc Dielectric

Raman and Far-Infrared Synchrotron Nanospectroscopy of Layered Crystalline Talc: Vibrational Properties, Interlayer Coupling, and Symmetry Crossover

High throughput investigation of an emergent and naturally abundant 2D material: Clinochlore

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