ORCID Profile
0000-0002-5117-4233
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-03-2018
Abstract: Time-controlled plasma treatment of MoS 2 FETs improves carrier transport due to the presence of a two-dimensional oxide phase.
Publisher: Springer Science and Business Media LLC
Date: 16-02-2016
DOI: 10.1038/SREP21045
Abstract: Two-dimensional (2D) materials usually have a layer-dependent work function, which require fast and accurate detection for the evaluation of their device performance. A detection technique with high throughput and high spatial resolution has not yet been explored. Using a scanning electron microscope, we have developed and implemented a quantitative analytical technique which allows effective extraction of the work function of graphene. This technique uses the secondary electron contrast and has nanometre-resolved layer information. The measurement of few-layer graphene flakes shows the variation of work function between graphene layers with a precision of less than 10 meV. It is expected that this technique will prove extremely useful for researchers in a broad range of fields due to its revolutionary throughput and accuracy.
Publisher: AIP Publishing
Date: 22-10-2019
DOI: 10.1063/1.5115036
Abstract: We report a simple technique for the selective etching of bilayer and monolayer MoS2. In this work, chosen regions of MoS2 were activated for oxygen adsorption and reaction by the application of low doses of He+ at 30 keV in a gas ion microscope. Raman spectroscopy, optical microscopy, and scanning electron microscopy were used to characterize both the etched features and the remaining material. It has been found that by using a pretreatment to introduce defects, MoS2 can be etched very efficiently and with high region specificity by heating in air.
Publisher: IOP Publishing
Date: 27-06-2016
DOI: 10.1088/0957-4484/27/32/325302
Abstract: A focused helium ion beam was used to introduce nano-sized gap chains in graphene. The effect of beam scanning strategies in the fabrication of the nano-gap chains was investigated. The tuning of graphene conductivity has been achieved by modulating the magnitude and uniformity of the ion dose and hence the morphology of the nano-gap chains. A model based on the site-specific and dose-dependent conductivity was built to understand the tuning of the conductivity, taking into account the nanoscale non-uniformity of irradiation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5NR03251B
Abstract: An anisotropic resistance switching behavior has been observed in Fe 3 O 4 thin films on stepped SrTiO 3 substrates.
Publisher: American Chemical Society (ACS)
Date: 27-03-2017
Publisher: American Chemical Society (ACS)
Date: 02-11-2016
Abstract: In this study, an in vitro Caco-2 cell culture assay was employed to evaluate the correlation between emulsion structure and cellular uptake of encapsulated β-carotene. After 4 h of incubation, an emulsion stabilized with whey protein isolate showed the highest intracellular accumulation of β-carotene (1.06 μg), followed by that stabilized with sodium caseinate (0.60 μg) and Tween 80 (0.20 μg), which are 13-, 7.5-, and 2.5-fold higher than that of free β-carotene (0.08 μg), respectively. Emulsions with small droplet size (239 ± 5 nm) showed a higher cellular uptake of β-carotene (1.56 μg) than emulsiond with large droplet size (489 ± 9 nm) (0.93 μg) (p < 0.01). The results suggested that delivery in an emulsion significantly improved the cellular uptake of β-carotene and thus potentially its bioavailability uptake was closely correlated with the interfacial composition and droplet size of emulsions. The findings support the potential for achieving optimal controlled and targeted delivery of bioactive nutrients by structuring emulsions.
Publisher: Elsevier BV
Date: 07-2016
Publisher: Springer Science and Business Media LLC
Date: 13-11-2014
DOI: 10.1038/SREP07032
Publisher: Springer Science and Business Media LLC
Date: 08-02-2016
DOI: 10.1038/SREP20704
Abstract: Cobalt hydrate and doped binary Co 0.9 M 0.1 OOH (M = Ni, Mn, Fe) nanorings of 100–300 nm were fabricated in solution through a facile ambient oxidation method. A transformation from Co 0.9 Ni 0.1 (OH) 2 nanodiscs to hollow Co 0.9 Ni 0.1 OOH nanorings was observed with prolonged reaction time. Core-shell nanodiscs have elemental segregation with a Co(OH) 2 core and Ni(OH) 2 shell. Co 0.9 Ni 0.1 OOH nanorings displayed a higher electrochemical capacitance than Mn and Fe doped nanorings materials or materials with disc-like geometries.
Publisher: AIP Publishing
Date: 14-02-2019
DOI: 10.1063/1.5086366
Abstract: We investigate the effects of lattice disorders on the low frequency Raman spectra of bilayer MoS2. The bilayer MoS2 was subjected to defect engineering by irradiation with a 30 keV He+ ion beam, and the induced morphology change was characterized by transmission electron microscopy. When increasing the ion dose, the shear mode is observed to red-shift, and it is also suppressed sharply compared to other Raman peaks. We use the linear chain model to describe the changes to the Raman spectra. Our observations suggest that the crystallite size and orientation are the dominant factors behind the changes to the Raman spectra.
Publisher: American Chemical Society (ACS)
Date: 15-07-2015
DOI: 10.1021/ACS.NANOLETT.5B01673
Abstract: We report subnanometer modification enabled by an ultrafine helium ion beam. By adjusting ion dose and the beam profile, structural defects were controllably introduced in a few-layer molybdenum disulfide (MoS2) s le and its stoichiometry was modified by preferential sputtering of sulfur at a few-nanometer scale. Localized tuning of the resistivity of MoS2 was demonstrated and semiconducting, metallic-like, or insulating material was obtained by irradiation with different doses of He(+). Amorphous MoSx with metallic behavior has been demonstrated for the first time. Fabrication of MoS2 nanostructures with 7 nm dimensions and pristine crystal structure was also achieved. The damage at the edges of these nanostructures was typically confined to within 1 nm. Nanoribbons with widths as small as 1 nm were reproducibly fabricated. This nanoscale modification technique is a generalized approach that can be applied to various two-dimensional (2D) materials to produce a new range of 2D metamaterials.
Publisher: IOP Publishing
Date: 04-04-2016
DOI: 10.1088/0957-4484/27/19/195302
Abstract: A flexible and efficient method to fabricate nanopores in graphene has been developed. A focused, low-energy (5 keV) electron beam was used to locally activate etching of a graphene surface in a low pressure (0.3 Pa) N2 environment. Nanopores with sub-5 nm diameters were fabricated. The lattice structure of the graphene was observed to recover within 20 nm of the nanopore edge. Nanopore growth rates were investigated systematically. The effects of nitrogen pressure, electron beam dwell time and beam current were characterised in order to understand the etching mechanism and enable optimisation of the etching parameters. A model was developed which describes how the diffusion of ionised nitrogen affects the nanopore growth rate. Etching of other two-dimensional materials was attempted as demonstrated with MoS2. The lack of etching observed supports our model of a chemical reaction-based mechanism. The understanding of the etching mechanism will allow more materials to be etched by selection of an appropriate ion species.
No related grants have been discovered for Pierce Maguire.