Effect of Ultraviolet-Ozone Treatment on MoS2 Monolayers: Comparison of Chemical-Vapor-Deposited Polycrystalline Thin Films and Mechanically Exfoliated Single Crystal Flakes

Jung, Changki; Yang, Hae In; Choi, Woong

doi:10.1186/s11671-019-3119-3

Cited by 31 publications

(26 citation statements)

References 30 publications

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“…The low I PL near the periphery overlaps with the AFM-observed line defects present in the O 2 -treated MoS 2 . These results suggest that, unlike for samples treated using harsh oxidations [ 18 , 20 , 22 ], physisorbed O 2 at the center of the crystal actually results in an enhancement of I PL , which is in accordance with the previous report [ 17 ]. In contrast, chemically oxygenated species evidenced by line defects form near the periphery and result in the reduced I PL .…”

Section: Resultssupporting

confidence: 92%

“…The effects of environmentally abundant oxygen and water on the optoelectronic properties of MoS 2 have been studied [ 17 , 18 , 19 ], but how these species affect the doping and ε properties of MoS 2 under ambient conditions remains largely unknown, and this is an important issue. Treatments under harsh oxidative conditions such as with oxygen plasma [ 18 ], UV-ozone [ 20 ], and high-temperature annealing (>300 °C) [ 18 , 21 , 22 ] are known to induce oxidation of the basal plane of MoS 2 . Following these treatments, the basal plane of MoS 2 exhibits reduced photoluminescence (PL), while edges and cracked regions display increased PL, suggesting that oxidation plays different roles in governing the properties of the basal plane and periphery.…”

Section: Introductionmentioning

confidence: 99%

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Long-Term Exposure of MoS2 to Oxygen and Water Promoted Armchair-to-Zigzag-Directional Line Unzippings

Song

Park

et al. 2022

Nanomaterials

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Understanding the long-term stability of MoS2 is important for various optoelectronic applications. Herein, we show that the long-term exposure to an oxygen atmosphere for up to a few months results in zigzag (zz)-directional line unzipping of the MoS2 basal plane. In contrast to exposure to dry or humid N2 atmospheres, dry O2 treatment promotes the initial formation of line defects, mainly along the armchair (ac) direction, and humid O2 treatment further promotes ac line unzipping near edges. Further incubation of MoS2 for a few months in an O2 atmosphere results in massive zz-directional line unzipping. The photoluminescence and the strain-doping plot based on two prominent bands in the Raman spectrum show that, in contrast to dry-N2-treated MoS2, the O2-treated MoS2 primarily exhibits hole doping, whereas humid-O2-treated MoS2 mainly exists in a neutral charge state with tension. This study provides a guideline for MoS2 preservation and a further method for generating controlled defects.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Long-Term Exposure of MoS2 to Oxygen and Water Promoted Armchair-to-Zigzag-Directional Line Unzippings

Song

Park

et al. 2022

Nanomaterials

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“…Recently, the transport, electronic, and optoelectronic properties of 2D MoS 2 have been modified by various surface functionalization techniques, including thermal, − oxygen-plasma, − and UV–ozone oxidation. − Some of these functionalization techniques can lead to the complete/partial conversion of the topmost 2D MoS 2 layer(s) into 2D surface oxides, yielding stoichiometric MoO 3 after careful process optimization. There have been few reports of such atomic layer conversion of 2D MoS 2 into 2D MoO 3 with a very limited characterization of the oxide. ,,,, As such, a detailed and comprehensive study of the 2D monolayer MoO 3 has yet to be conducted. Moreover, no report of large-area single-layer MoO 3 has been reported to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

“…There have been few reports of such atomic layer conversion of 2D MoS 2 into 2D MoO 3 with a very limited characterization of the oxide. 39,42,43,47,48 As such, a detailed and comprehensive study of the 2D monolayer MoO 3 has yet to be conducted. Moreover, no report of large-area single-layer MoO 3 has been reported to the best of our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Wafer-Scalable Single-Layer Amorphous Molybdenum Trioxide

et al. 2022

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Molybdenum trioxide (MoO3), an important transition metal oxide (TMO), has been extensively investigated over the past few decades due to its potential in existing and emerging technologies, including catalysis, energy and data storage, electrochromic devices, and sensors. Recently, the growing interest in two-dimensional (2D) materials, often rich in interesting properties and functionalities compared to their bulk counterparts, has led to the investigation of 2D MoO3. However, the realization of large-area true 2D (single to few atom layers thick) MoO3 is yet to be achieved. Here, we demonstrate a facile route to obtain wafer-scale monolayer amorphous MoO3 using 2D MoS2 as a starting material, followed by UV–ozone oxidation at a substrate temperature as low as 120 °C. This simple yet effective process yields smooth, continuous, uniform, and stable monolayer oxide with wafer-scale homogeneity, as confirmed by several characterization techniques, including atomic force microscopy, numerous spectroscopy methods, and scanning transmission electron microscopy. Furthermore, using the subnanometer MoO3 as the active layer sandwiched between two metal electrodes, we demonstrate the thinnest oxide-based nonvolatile resistive switching memory with a low voltage operation and a high ON/OFF ratio. These results (potentially extendable to other TMOs) will enable further exploration of subnanometer stoichiometric MoO3, extending the frontiers of ultrathin flexible oxide materials and devices.

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“…Raman spectrometry was employed to examine the properties of MoS 2 after 30 min incubation in DI water [ 23 ]. As illustrated in Figure S1 , the absolute intensity of the two signature peaks of MoS 2 remained unaffected after the incubation, indicating there was no oxidation taking place.…”

Section: Resultsmentioning

confidence: 99%

Effect of Al2O3 Passive Layer on Stability and Doping of MoS2 Field-Effect Transistor (FET) Biosensors

et al. 2021

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Molybdenum disulfide (MoS2) features a band gap of 1.3 eV (indirect) to 1.9 eV (direct). This tunable band gap renders MoS2 a suitable conducting channel for field-effect transistors (FETs). In addition, the highly sensitive surface potential in MoS2 layers allows the feasibility of FET applications in biosensors, where direct immobilization and detection of biological molecules are conducted in wet conditions. In this work, we report, for the first time, the degradation of chemical vapor deposition (CVD) grown MoS2 FET-based sensors in the presence of phosphate buffer and water, which caused false positive response in detection. We conclude the degradation was originated by physical delamination of MoS2 thin films from the SiO2 substrate. The problem was alleviated by coating the sensors with a 30 nm thick aluminum oxide (Al2O3) layer using atomic layer deposition technique (ALD). This passive oxide thin film not only acted as a protecting layer against the device degradation but also induced a strong n-doping onto MoS2, which permitted a facile method of detection in MoS2 FET-based sensors using a low-power mode chemiresistive I-V measurement at zero gate voltage (Vgate = 0 V). Additionally, the oxide layer provided available sites for facile functionalization with bioreceptors. As immunoreaction plays a key role in clinical diagnosis and environmental analysis, our work presented a promising application using such enhanced Al2O3-coated MoS2 chemiresistive biosensors for detection of HIgG with high sensitivity and selectivity. The biosensor was successfully applied to detect HIgG in artificial urine, a complex matrix containing organics and salts.

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Effect of Ultraviolet-Ozone Treatment on MoS2 Monolayers: Comparison of Chemical-Vapor-Deposited Polycrystalline Thin Films and Mechanically Exfoliated Single Crystal Flakes

Cited by 31 publications

References 30 publications

Long-Term Exposure of MoS2 to Oxygen and Water Promoted Armchair-to-Zigzag-Directional Line Unzippings

Long-Term Exposure of MoS2 to Oxygen and Water Promoted Armchair-to-Zigzag-Directional Line Unzippings

Wafer-Scalable Single-Layer Amorphous Molybdenum Trioxide

Effect of Al2O3 Passive Layer on Stability and Doping of MoS2 Field-Effect Transistor (FET) Biosensors

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