Space charge neutralization by electron-transparent suspended graphene

Srisonphan, Siwapon; Kim, Myungji; Kim, Hong Koo

doi:10.1038/srep03764

Cited by 34 publications

(38 citation statements)

References 35 publications

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“…Due to the electron transparency of graphene [10,71,[159][160][161][162], thin layers of deposited GRM sheets might not be visible by Scanning Electron Microscope (SEM), particularly when high accelerating voltages are used; instead the underlying electrode structure may appear even in secondary electron images. Nevertheless, when low accelerating voltages (e.g.…”

Section: Conformabilitymentioning

confidence: 99%

Electrophoretic deposition of graphene-related materials: A review of the fundamentals

Diba

Fam

Boccaccını

et al. 2016

Progress in Materials Science

228

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The Electrophoretic Deposition (EPD) of graphene-related materials (GRM) is an attractive strategy for a wide range of applications. This review paper provides an overview of the fundamentals and specific technical aspects of this approach, highlighting its advantages and limitations. Since obtaining a stable dispersion of charged particles is a pre-requisite for successful EPD, the strategies for suspending GRM in different media are discussed, along with the resulting influence on the deposited film. Most importantly, the kinetics involved in the EPD of GRMs and the factors that cause deviation from linearity in Hamaker's Law are reviewed. Side reactions often influence both efficiency and the nature of the deposited material; examples include the reduction of graphene oxide (GO) and related materials, as well as the decomposition of the suspension medium at high potentials. The microstructural characteristics of GRM deposits, and their degree of reduction, strongly influence their performance in their intended function. These factors will also determine, to a large extent, the commercial potential of this technique for applications involving GRM, and are therefore discussed here.

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Section: Conformabilitymentioning

confidence: 99%

Electrophoretic deposition of graphene-related materials: A review of the fundamentals

Diba

Fam

Boccaccını

et al. 2016

Progress in Materials Science

228

View full text Add to dashboard Cite

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“…The work function of G has been reported to be 4.65-4.70 eV [43,44]. The observed 70 mV improvement of V OC of G based devices is therefore explained with a work function for ITO not larger than 4.58-4.63 eV, which is compatible with device quality, highly conductive ITO [2,45,46].…”

Section: Discussionmentioning

confidence: 88%

Graphene as transparent conducting layer for high temperature thin film device applications

Veronese

Allegrezza

Canino

et al. 2015

Solar Energy Materials and Solar Cells

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“…To increase the electron velocity, a high voltage is paired with a magnetic field or a gate electrode is introduced between cathode and anode which has been of interest recently (Meir et al, 2013;Wanke et al, 2016). A suitable electron transparent grid electrode was suggested by utilizing graphene that exhibited an electron transparency of ∼99.9% (Srisonphan et al, 2014). Mitigation of the electronic space charge has also been reported through the introduction of positive ions which can be generated through impact ionization for lower cathode temperatures of 1,200-1,500°C in an ignited or arc-mode converter (Hernqvist, 1963).…”

Section: Vacuum Thermionic Energy Conversionmentioning

confidence: 99%

Advances in Thermionic Energy Conversion through Single-Crystal n-Type Diamond

Koeck

Nemanich

2017

Front. Mech. Eng.

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Thermionic energy conversion, a process that allows direct transformation of thermal to electrical energy, presents a means of efficient electrical power generation as the hot and cold side of the corresponding heat engine are separated by a vacuum gap. Conversion efficiencies approaching those of the Carnot cycle are possible if material parameters of the active elements at the converter, i.e., electron emitter or cathode and collector or anode, are optimized for operation in the desired temperature range. These parameters can be defined through the law of Richardson-Dushman that quantifies the ability of a material to release an electron current at a certain temperature as a function of the emission barrier or work function and the emission or Richardson constant. Engineering materials to defined parameter values presents the key challenge in constructing practical thermionic converters. The elevated temperature regime of operation presents a constraint that eliminates most semiconductors and identifies diamond, a wide band-gap semiconductor, as a suitable thermionic material through its unique material properties. For its surface, a configuration can be established, the negative electron affinity, that shifts the vacuum level below the conduction band minimum eliminating the surface barrier for electron emission. In addition, its ability to accept impurities as donor states allows materials engineering to control the work function and the emission constant. Singlecrystal diamond electrodes with nitrogen levels at 1.7 eV and phosphorus levels at 0.6 eV were prepared by plasma-enhanced chemical vapor deposition where the work function was controlled from 2.88 to 0.67 eV, one of the lowest thermionic work functions reported. This work function range was achieved through control of the doping concentration where a relation to the amount of band bending emerged. Upward band bending that contributed to the work function was attributed to surface states where lower doped homoepitaxial films exhibited a surface state density of ∼3 × 10 11 cm −2 . With these optimized doped diamond electrodes, highly efficient thermionic converters are feasible with a Schottky barrier at the diamond collector contact mitigated through operation at elevated temperatures.

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Space charge neutralization by electron-transparent suspended graphene

Cited by 34 publications

References 35 publications

Electrophoretic deposition of graphene-related materials: A review of the fundamentals

Electrophoretic deposition of graphene-related materials: A review of the fundamentals

Graphene as transparent conducting layer for high temperature thin film device applications

Advances in Thermionic Energy Conversion through Single-Crystal n-Type Diamond

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