Caveats in obtaining high-quality 2D materials and property characterization

Subramanian, S.; Briggs, Natalie; Shallenberger, Jeffrey R.; Wetherington, Maxwell

doi:10.1557/jmr.2019.394

Cited by 5 publications

(5 citation statements)

References 46 publications

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“…A redshift in the mean A excitonic peak position from 1.82 to 1.80 eV was noted following irradiation and may indicate a reduction in the band gap of MoS 2 due to tensile strain, potentially stemming from the introduced sulfur vacancies. While this shift exceeds the spectral resolution of the PL measurements (3 × 10 –4 eV), thus indicating statistical significance, shifts of similar or greater magnitude may also be induced by environmental factors; as the sample was irradiated in an ambient environment, correlation of the PL results with additional material characterization ( i.e. , Raman spectroscopy) is necessary for determining the significance of the observed shift.…”

Section: Resultsmentioning

confidence: 90%

“…Together, the PL and Raman spectroscopy results indicate that the pre-irradiation MoS 2 film is both uniform and of high quality and that, while there may be a slight increase in defect density due to irradiation-induced damage, the magnitude of radiation impact appears low even at a TID of 1 Mrad, with little-to-no effect on film uniformity and quality. As the post-irradiation shift in the Raman spectra is on the order of the spectral resolution (∼0.5 cm –1 ), the radiation impact cannot be held as statistically significant despite the apparent significance of the change in the PL peak position (0.02 eV with a spectral resolution of ∼3 × 10 –4 eV); these changes are no more extreme than what can be expected to occur in large-area MoS 2 if it is exposed to air for the same amount of time as it took for irradiation to be completed and may even be artifacts induced by the laser used during spectroscopy . While prior studies on gamma irradiation of MoS 2 have reported a blueshift in the post-irradiation E 2 g 1 and A 1 g peaks of the Raman spectra, , it is important to note that most of these studies were conducted at higher TIDs than the 1 Mrad utilized in this work.…”

Section: Resultsmentioning

confidence: 98%

“…As the post-irradiation shift in the Raman spectra is on the order of the spectral resolution (∼0.5 cm −1 ), the radiation impact cannot be held as statistically significant despite the apparent significance of the change in the PL peak position (0.02 eV with a spectral resolution of ∼3 × 10 −4 eV); these changes are no more extreme than what can be expected to occur in large-area MoS 2 if it is exposed to air for the same amount of time as it took for irradiation to be completed and may even be artifacts induced by the laser used during spectroscopy. 39 While prior studies on gamma irradiation of MoS 2 have reported a blueshift in the post-irradiation E 2g 1 and A 1g peaks of the Raman spectra, 8,28 it is important to note that most of these studies were conducted at higher TIDs than the 1 Mrad utilized in this work. From the work of Singh and Singh, 28 a blueshift in the Raman spectra of monolayer MoS 2 can only be seen when the TID exceeds ∼5 Mrad; conversely, at a TID of 1 Mrad, little-to-no change is seen in the Raman Figure 4a shows the pre-irradiation transfer characteristics, i.e., source-to-drain current (I DS ) vs back-gate voltage (V BG ), of 132 MoS 2 memtransistors taken at a drain voltage (V DS ) of 1 V. The back-gate voltage was swept from 3 to −2 V in steps of 50 mV and back.…”

Section: Figure 1amentioning

confidence: 93%

See 2 more Smart Citations

Radiation Resilient Two-Dimensional Electronics

Schranghamer

Pannone

Ravichandran

et al. 2023

ACS Appl. Mater. Interfaces

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Limitations in cloud-based computing have prompted a paradigm shift toward all-in-one “edge” devices capable of independent data sensing, computing, and storage. Advanced defense and space applications stand to benefit immensely from this due to their need for continual operation in areas where maintaining remote oversight is difficult. However, the extreme environments relevant to these applications necessitate rigorous testing of technologies, with a common requirement being hardness to ionizing radiation. Two-dimensional (2D) molybdenum disulfide (MoS2) has been noted to enable the sensing, storage, and logic capabilities necessary for all-in-one edge devices. Despite this, the investigation of ionizing radiation effects in MoS2-based devices remains incomplete. In particular, studies on gamma radiation effects in MoS2 have been largely limited to standalone films, with few device investigations; to the best of our knowledge, no explorations have been made into gamma radiation effects on the sensing and memory capabilities of MoS2-based devices. In this work, we have used a statistical approach to study high-dose (1 Mrad) gamma radiation effects on photosensitive and programmable memtransistors fabricated from large-area monolayer MoS2. Memtransistors were divided into separate groups to ensure accurate extraction of device characteristics pertaining to baseline performance, sensing, and memory before and after irradiation. All-MoS2 logic gates were also assessed to determine the gamma irradiation impact on logic implementation. Our findings show that the multiple functionalities of MoS2 memtransistors are not severely impacted by gamma irradiation even without dedicated shielding/mitigation techniques. We believe that these results serve as a foundation for more application-oriented studies going forward.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 98%

Section: Figure 1amentioning

confidence: 93%

See 1 more Smart Citation

Radiation Resilient Two-Dimensional Electronics

Schranghamer

Pannone

Ravichandran

et al. 2023

ACS Appl. Mater. Interfaces

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“…Apart from the 791 °C sample, the stoichiometric values are within 5% of the nominal value of 2.0. As the error on the measured stoichiometries is in the 3%-5% range, it is not possible to quantitatively correlate the (opto)electronic properties to the stoichiometry determined by XPS [68]. Nevertheless, due to the large FWHM of the W4f and W3p3/ 2, as well as the Se3d core levels, the strongest defect-induced PL emission is expected for the 791 °C sample, which was indeed confirmed in the low-temperature-PL measurement given in figure 3(a).…”

Section: Resultsmentioning

confidence: 99%

Impact of synthesis temperature and precursor ratio on the crystal quality of MOCVD WSe₂ monolayers

et al. 2023

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Structural defects in transition metal dichalcogenide (TMDC) monolayers (ML) play a significant role in determining their (opto)electronic properties, triggering numerous efforts to control defect densities during material growth or by post-growth treatments. Various types of TMDC have been successfully deposited by MOCVD (metal-organic chemical vapor deposition), which is a wafer-scale deposition technique with excellent uniformity and controllability. However, so far there are no findings on the extent to which the incorporation of defects can be controlled by growth parameters during MOCVD processes of TMDC. In this work, we investigate the effect of growth temperature and precursor ratio during MOCVD of tungsten diselenide (WSe2) on the growth of ML domains and their impact on the density of defects. The aim is to find parameter windows that enable the deposition of WSe2 ML with high crystal quality, i.e. a low density of defects. Our findings confirm that the growth temperature has a large influence on the crystal quality of TMDC, significantly stronger than found for the W to Se precursor ratio. Raising the growth temperatures in the range of 688 °C to 791 °C leads to an increase of the number of defects, dominating photoluminescence (PL) at low temperatures (5.6 K). In contrast, an increase of the molar precursor ratio (DiPSe/WCO) from 1,000 up to 100,000 leads to less defect-related PL at low temperatures.

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“…Recent work has demonstrated high temperature (>BEOL thermal budget) CVD-growth of MoS 2 on sacrificial 300 mm wafers with subsequent film transfer for device fabrication [25]. Moreover, it should be noted that caveats abound in the interpretation of TMD properties, and achieving reliable electronicsgrade devices for logic applications is extremely challenging [52].…”

Section: Introductionmentioning

confidence: 99%

Large-area growth of MoS₂ at temperatures compatible with integrating back-end-of-line functionality

Lin¹,

Monaghan²,

Sakhuja³

et al. 2020

2D Mater.

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Direct growth of transition metal dichalcogenides over large areas within the back-end-of-line (BEOL) thermal budget limit of silicon integrated circuits is a significant challenge for 3D heterogeneous integration. In this work, we report on the growth of MoS 2 films (∼1-10 nm) on SiO 2 , amorphous-Al 2 O 3 , c-plane sapphire, and glass substrates achieved at low temperatures (350 • C-550 • C) by chemical vapor deposition in a manufacturing-compatible 300 mm atomic layer deposition reactor. We investigate the MoS 2 films as a potential material solution for BEOL logic, memory and sensing applications. Hall-effect/4-point measurements indicate that the ∼10 nm MoS 2 films exhibit very low carrier concentrations (10 14 -10 15 cm −3 ), high resistivity, and Hall mobility values of ∼0.5-17 cm 2 V −1 s −1 , confirmed by transistor and resistor test device results. MoS 2 grain boundaries and stoichiometric defects resulting from the low thermal budget growth, while detrimental to lateral transport, can be leveraged for the integration of memory and sensing functions. Vertical transport memristor structures (Au/MoS 2 /Au) incorporating ∼3 nm thick MoS 2 films grown at 550 • C (∼0.75 h) show memristive switching and a stable memory window of 10 5 with a retention time >10 4 s, between the high-low resistive states. The switching set and reset voltages in these memristors demonstrate a significant reduction compared to memristors fabricated from pristine, single-crystalline MoS 2 at higher temperatures, thereby reducing the energy needed for operation. Furthermore, interdigitated electrode-based gas sensors fabricated on ∼5 nm thick 550 • C-grown (∼1.25 h) MoS 2 films show excellent selectivity and sub-ppm sensitivity to NO 2 gas, with a notable self-recovery at room temperature. The demonstration of large-area MoS 2 direct growth at and below the BEOL thermal budget limit, alongside memristive and gas sensing functionality, advances a key enabling technology objective in emerging materials and devices for 3D heterogeneous integration. Recently, transition metal dichalcogenides (TMDs) have emerged from the graphene initiatives due to the diverse functionality offered by the incorporation of this class of 2D layered material. More specifically,

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Caveats in obtaining high-quality 2D materials and property characterization

Abstract: Abstract

Cited by 5 publications

References 46 publications

Radiation Resilient Two-Dimensional Electronics

Radiation Resilient Two-Dimensional Electronics

Impact of synthesis temperature and precursor ratio on the crystal quality of MOCVD WSe₂ monolayers

Large-area growth of MoS₂ at temperatures compatible with integrating back-end-of-line functionality

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Caveats in obtaining high-quality 2D materials and property characterization

Abstract: Abstract

Cited by 5 publications

References 46 publications

Radiation Resilient Two-Dimensional Electronics

Radiation Resilient Two-Dimensional Electronics

Impact of synthesis temperature and precursor ratio on the crystal quality of MOCVD WSe2 monolayers

Large-area growth of MoS2 at temperatures compatible with integrating back-end-of-line functionality

Contact Info

Product

Resources

About

Impact of synthesis temperature and precursor ratio on the crystal quality of MOCVD WSe₂ monolayers

Large-area growth of MoS₂ at temperatures compatible with integrating back-end-of-line functionality