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Observation of negative differential resistance in mesoscopic graphene oxide devices.

ABSTRACT: The fractions of various functional groups in graphene oxide (GO) are directly related to its electrical and chemical properties and can be controlled by various reduction methods like thermal, chemical and optical. However, a method with sufficient controllability to regulate the reduction process has been missing. In this work, a hybrid method of thermal and joule heating processes is demonstrated where a progressive control of the ratio of various functional groups can be achieved in a localized area. With this precise control of carbon-oxygen ratio, negative differential resistance (NDR) is observed in the current-voltage characteristics of a two-terminal device in the ambient environment due to charge-activated electrochemical reactions at the GO surface. This experimental observation correlates with the optical and chemical characterizations. This NDR behavior offers new opportunities for the fabrication and application of such novel electronic devices in a wide range of devices applications including switches and oscillators.

SUBMITTER: Rathi S

PROVIDER: S-EPMC5940784 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Light-induced negative differential resistance in graphene/Si-quantum-dot tunneling diodes.

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| S-EPMC4964343 | biostudies-literature

Differential cytotoxic effects of graphene and graphene oxide on skin keratinocytes.

Project description:Impressive properties make graphene-based materials (GBMs) promising tools for nanoelectronics and biomedicine. However, safety concerns need to be cleared before mass production of GBMs starts. As skin, together with lungs, displays the highest exposure to GBMs, it is of fundamental importance to understand what happens when GBMs get in contact with skin cells. The present study was carried out on HaCaT keratinocytes, an in vitro model of skin toxicity, on which the effects of four GBMs were evaluated: a few layer graphene, prepared by ball-milling treatment (FLG), and three samples of graphene oxide (GOs, a research-grade GO1, and two commercial GOs, GO2 and GO3). Even though no significant effects were observed after 24?h, after 72?h the less oxidized compound (FLG) was the less cytotoxic, inducing mitochondrial and plasma-membrane damages with EC50s of 62.8??g/mL (WST-8 assay) and 45.5??g/mL (propidium iodide uptake), respectively. By contrast, the largest and most oxidized compound, GO3, was the most cytotoxic, inducing mitochondrial and plasma-membrane damages with EC50s of 5.4 and 2.9??g/mL, respectively. These results suggest that only high concentrations and long exposure times to FLG and GOs could impair mitochondrial activity associated with plasma membrane damage, suggesting low cytotoxic effects at the skin level.

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Negative differential resistance in boron nitride graphene heterostructures: physical mechanisms and size scaling analysis.

Project description:Hexagonal boron nitride (hBN) is drawing increasing attention as an insulator and substrate material to develop next generation graphene-based electronic devices. In this paper, we investigate the quantum transport in heterostructures consisting of a few atomic layers thick hBN film sandwiched between graphene nanoribbon electrodes. We show a gate-controllable vertical transistor exhibiting strong negative differential resistance (NDR) effect with multiple resonant peaks, which stay pronounced for various device dimensions. We find two distinct mechanisms that are responsible for NDR, depending on the gate and applied biases, in the same device. The origin of first mechanism is a Fabry-Pérot like interference and that of the second mechanism is an in-plane wave vector matching when the Dirac points of the electrodes align. The hBN layers can induce an asymmetry in the current-voltage characteristics which can be further modulated by an applied bias. We find that the electron-phonon scattering suppresses the first mechanism whereas the second mechanism remains relatively unaffected. We also show that the NDR features are tunable by varying device dimensions. The NDR feature with multiple resonant peaks, combined with ultrafast tunneling speed provides prospect for the graphene-hBN-graphene heterostructure in the high-performance electronics.

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Observation of room-temperature negative differential resistance in Gd-doped Si nanowires on Si(110) surface.

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| S-EPMC3422321 | biostudies-other

Influence of Humidity on Contact Resistance in Graphene Devices.

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| S-EPMC6284205 | biostudies-literature

Electrodiffusioosmosis induced negative differential resistance in micro-to-millimeter size pores through a graphene/copper membrane.

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| S-EPMC9680926 | biostudies-literature

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Adsorption-Induced Expansion of Graphene Oxide Frameworks: Observation by in Situ Neutron Diffraction.

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