Band-like transport in highly crystalline graphene films from defective graphene oxides

Negishi, Ryota; Akabori, Masashi; Ito, Takahiro; Watanabe, Yoshio; Kobayashi, Yoshihiro

doi:10.1038/srep28936

Cited by 72 publications

(69 citation statements)

References 39 publications

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“…Presumably, in conducting domains, the subsequent annealing of a RGO sample removes defects and increases carrier concentrations [10−12]. Previously, it has been observed that the annealing of the RGO can lead to a Fermi level shift in the disordered graphitic sample due to generation of additional carriers [54,55]. Therefore, we can apply equation (6) in this case as well which can explain the ∆Σ ∝−∆n eff 0.5 behavior in the conducting domains of the RGO.…”

Section: Mmentioning

confidence: 99%

Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide

Shekhar

Lee

Cho

et al. 2019

Carbon

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et al.. Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide. Carbon, Elsevier, 2019, 148, pp. ABSTRACTWe report a nanoscale mapping of noise-source-controlled transport characteristics in the domains of reduced graphene oxide by utilizing noise-source imaging strategies. In this method, current and noise images were measured simultaneously using a scanning noise microscopy and analyzed to map sheet−resistances (R ) and noise−source densities (n eff ). The maps showed the formation of conducting and insulating domains, where the insulating domains exhibited up to three-four orders of higher R and n eff than those of conducting domains. Interestingly, the sheet−conductance (Σ ) and n eff followed rather opposite power−law behaviors like Σ ∝ n eff −0.5 and Σ ∝ n eff 0.5 in conducting and insulating domains, respectively, which could be attributed to the difference in mesoscopic charge transport mechanisms controlled by n eff in domains. Notably, high biases resulted in the increased conductance (∆Σ ) and decreased noise−source density (∆n eff ) following a relationship like ∆Σ ∝−∆n eff 0.5 for both conducting and insulting domains, which could be explained by the passivation of noise−sources at high biases. Furthermore, ∆Σ versus ∆n eff plot on the annealing also followed a power−law dependence (∆Σ ∝−∆n eff 0.5 ) in conducting domains, which could be attributed to carrier generation on the annealing. Our results about mesoscopic charge transports could be significant advancements in fundamental researches and applications.

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Section: Mmentioning

confidence: 99%

Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide

Shekhar

Lee

Cho

et al. 2019

Carbon

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“…11,24,25) Theoretical calculation indicates that the work function of the rGO with an oxygen concentration in the 10-20% range can be tunable between 5.0-5.5 eV. 26) For example, the calculated work function of the hydroxyl group (5.0-5.3 eV) is higher than that of graphene (4.2 eV).…”

Section: Methodsmentioning

confidence: 99%

“…5(a) and 5(b). From the transmission electron microscopy observations in a previous study, 11) we found that such defects as vacancies and amorphous-like π networks composed of a mixture of sp 2 and sp 3 structures remain in the rGO films prepared by a low process temperature below 900°C. The amorphous-like π networks have a larger work function (4.9-5.0 eV) 32) than graphite or graphene.…”

Section: Methodsmentioning

confidence: 99%

“…Under the latter condition, the structural restoration due to healing defects efficiently proceeds by a mixture of carrier gas at 250 standard cubic centimeters per minute (sccm) and ethanol vapor at 0.5 sccm. 10,11) If the ethanol flow rate exceeds the rate used here, the formation of multilayer graphene proceeds through graphene overlayer growth. [19][20][21] 3.…”

Section: Methodsmentioning

confidence: 99%

“…[5][6][7] Since the GO produced by the oxidation of graphite has rich oxygen functional groups and is an insulating material, the reduction process is necessary for electrical device applications. Many reduction processes such as thermal treatment in inert=reactive environments, [8][9][10][11] chemical [12][13][14] and electrochemical 15) reductions have been explored. The crystallinity and amount of oxygen functional groups in reduced graphene oxide (rGO) strongly depend on the reduction conditions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of surface potentials in reduced graphene oxide flake by Kelvin probe force microscopy

Negishi¹,

Takashima²,

Kobayashi³

2018

Jpn. J. Appl. Phys.

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The surface potential (SP) of reduced graphene oxide (rGO) flakes prepared by thermal treatments of GO under several conditions was analyzed by Kelvin probe force microscopy. The low-crystalline rGO flakes in which a significant amount of oxygen functional groups and structural defects remain have a much lower SP than mechanically exfoliated graphene free from oxygen and defects. On the other hand, the highly crystalline rGO flake after a thermal treatment for the efficient removal of oxygen functional groups and healing of structural defects except for domain boundary shows SP equivalent to that of the mechanically exfoliated graphene. These results indicate that the work function of rGO is sensitively modulated by oxygen functional groups and structural defects remaining after the thermal reduction process, but is not affected significantly by the domain boundary remaining after the healing of structural defects through the thermal treatment at high temperature.

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Ultrasensitive Molecular Sensors Based on Real‐Time Impedance Spectroscopy in Solution‐Processed 2D Materials

Moore

Jawaid

Busch

et al. 2021

Adv Funct Materials

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Chemical sensors based on solution‐processed 2D nanomaterials represent an extremely attractive approach toward scalable and low‐cost devices. Through the implementation of real‐time impedance spectroscopy and development of a three‐element circuit model, redox exfoliated MoS2 nanoflakes demonstrate an ultrasensitive empirical detection limit of NO2 gas at 1 ppb, with an extrapolated ultimate detection limit approaching 63 ppt. This sensor construct reveals a more than three orders of magnitude improvement from conventional direct current sensing approaches as the traditionally dominant interflake interactions are bypassed in favor of selectively extracting intraflake doping effects. This same approach allows for an all solution‐processed, flexible 2D sensor to be fabricated on a polyimide substrate using a combination of graphene contacts and drop‐casted MoS2 nanoflakes, exhibiting similar sensitivity limits. Finally, a thermal annealing strategy is used to explore the tunability of the nanoflake interactions and subsequent circuit model fit, with a demonstrated sensitivity improvement of 2× with thermal annealing at 200 °C.

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Band-like transport in highly crystalline graphene films from defective graphene oxides

Cited by 72 publications

References 39 publications

Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide

Nanoscale mapping of noise-source-controlled hopping and tunneling conduction in domains of reduced graphene oxide

Investigation of surface potentials in reduced graphene oxide flake by Kelvin probe force microscopy

Ultrasensitive Molecular Sensors Based on Real‐Time Impedance Spectroscopy in Solution‐Processed 2D Materials

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