Large-area high-throughput synthesis of monolayer graphene sheet by Hot Filament Thermal Chemical Vapor Deposition

Hawaldar, Ranjit; Merino, Pablo; Correia, M. R.; Bdikin, Igor; Grácio, J.; Méndez, Javier; Martín‐Gago, José A.; Singh, Manoj K.

doi:10.1038/srep00682

Cited by 151 publications

(126 citation statements)

References 58 publications

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“…A similar situation due to reactions of the water-soluble PEIE with moisture in air was also found in the case of electron-doped graphene shown in Fig. 8(b), where the spectrum of the binding energy of C-1s core electron exhibited an increase of the C-C¼O component (at 288.7 eV) 21,22 with time plus a small trace of the C-OH component (at 285.7 eV). The relevant chemical reaction here may involve either…”

Section: Results and Analysissupporting

confidence: 76%

“…As shown in Fig. 8(a) for hole-doped monolayer graphene in air, the binding energy of the C-1s core electron appeared to increase with time up to 0.15 eV after 30 days, which was accompanied by increasing strengths of the sp 2 hybridized C-OH (at 285.7 eV) and the sp 3 C-O (at 286.6 eV) components of a comparable binding energy 21,22 as indicated by the arrow. The formation of the C-OH and C-O bonds may be understood as the result of the reaction of H 3 O þ with graphene, leading to either H 3 2À .…”

Section: Results and Analysismentioning

confidence: 86%

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Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

Chang

Hsu

Liu

et al. 2016

Journal of Applied Physics

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The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H 2 O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.

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Section: Results and Analysissupporting

confidence: 76%

Section: Results and Analysismentioning

confidence: 86%

Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

Chang

Hsu

Liu

et al. 2016

Journal of Applied Physics

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“…In recent years, there has been great improvement on the synthesis of high quality graphene using various methods, including chemical vapor deposition (CVD) grown graphene on different metal foils [137][138][139][140][141][142][143][144][145], and synthesis of epitaxial graphene on SiC substrates [146][147][148][149]. Moreover, recent low-cost rollto-roll [150,151] and large-area [146,152] synthesis methods have reduced the cost of graphene.…”

Section: Nw Growth On Graphenementioning

confidence: 99%

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

et al. 2014

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This thesis deals with the growth of GaAs nanowires (NWs) by molecular beam epitaxy (MBE) using vapor-liquid-solid method on various substrates including GaAs(111)B, Si(111) and graphene. The growth of the NWs on GaAs substrates was carried out by Au-catalyzed technique, whereas the growths on Si and graphene substrates were carried out using self-catalyzed technique that has been the main focus of this thesis. The long-term goal of this work was to produce p-n radial junction GaAs NWs for solar cell applications.Necessary conditions were established for obtaining vertical self-catalyzed GaAs NWs on Si(111), which is reproducible from run-to-run. One of the major issues in these NWs grown by both Au-and self-catalyzed techniques is their crystal structure. The Au-catalyzed GaAs NWs usually adopt a wurtzite (WZ) crystal phase, whereas the self-catalyzed NWs a zinc blende (ZB) phase. However, in both the cases the NWs contain stacking faults, rotational twins or/and a mixed crystal phase. The ZB and WZ phases show different optical properties, and one phase might be favored over other for certain applications. Therefore the crystal phase was controlled within single NWs by tuning the V/III ratio and introducing GaAsSb inserts. The change of the crystal phases was correlated with the change in the contact angle of the Ga droplet.Since the discovery of graphene, an ultra-thin two-dimensional material, the research on graphene has become an active field in recent years due to its remarkable properties including excellent electrical and thermal conductivities, mechanical strength and flexibility, and optical transparency. By growing the semiconductor NWs on graphene, a completely new hybrid system can be envisioned where the unique properties of both NWs and graphene can be utilized. Therefore we established a method for the growth of semiconductor NWs on graphene by demonstrating epitaxial growth of vertical GaAs and InAs NWs on different graphitic substrates.Core-shell heterostructure, doping, optical properties, and position controlled growth of self-catalyzed GaAs NWs were investigated. Growth of GaAs/GaAsSb coreshell NWs where the Sb content was tuned from about 10% -70% was studied. The effect of growth temperature and the Sb flux on the morphology of GaAsSb shell was investigated. In addition, by utilizing the core-shell geometry where the shell copies the crystal phase of the core, WZ phase of GaAsSb was demonstrated. Successful p-type doping of GaAs core using Be as dopant, and n-type doping of GaAs shell using Si and Te as dopants were achieved. To investigate the optical properties, GaAs/AlGaAs coreshell NWs were grown with different V/III ratios during the core growth. The NWs grown with high V/III ratio, despite containing a higher density of twinned ZB and WZ GaAs with SFs, were found to have superior optical quality as compared to the NWs grown with low V/III ratio that contain pure ZB GaAs. The observed V/III ratio dependent optical quality was correlated to the intrinsic defects such as As vac...

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“…Numerous functional graphene materials have now been synthesized using different structural motifs including metal-organic frameworks, polymers, biomaterials, organic crystals, and inorganic nanostructures. Several synthetic approaches, such as chemical vapor deposition (CVD), [5][6][7] micromechanical exfoliation, [ 5,8 ] epitaxial growth on SiC, [ 8,9 ] solution route wet chemical exfoliation, [ 10 ] sonochemical liquid-phase exfoliation, [ 8,11 ] of Gly·HSO 4 is equal to the total molecular mass of starting glycine and H 2 SO 4 ), being low-cost, and environmentally friendly, and has been applied previously for organocatalysis. [35][36][37] To date, it has not been applied in the electrochemical processing of graphene.…”

Section: Introductionmentioning

confidence: 99%

“…Within this broader processing regime the use of ionic liquids [23][24][25] are of particular interest due to their suitability as electrolytes. Previously, Liu et al [ 23 ] and Lu et al [ 24 ] have demonstrated the preparation of graphene via the electrochemical intercalation of PF 6 − and BF 4 − anions into graphite layers using alkylimidazolium hexafl uorophosphate (RIMPF 6 ) and alkylimidazolium tetrafl uoroborate (RIMBF 4 ) ionic liquids. Ionic liquids have several merits, including negligible vapor pressure, low toxicity, high chemical and thermal stability, and ease of availability.…”

mentioning

confidence: 99%

Soft Processing of Graphene Nanosheets by Glycine‐Bisulfate Ionic‐Complex‐Assisted Electrochemical Exfoliation of Graphite for Reduction Catalysis

Rao

Sentilnathan

Cho

et al. 2014

Adv Funct Materials

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This study demonstrates a mild, environmentally friendly, and cost‐effective soft processing approach for the continuous synthesis of high‐quality, few‐layer graphene nanosheets. This has been achieved via electrochemical exfoliation of graphite, using an environmentally friendly glycine‐bisulfate ionic complex and was performed under ambient reaction conditions. Graphene nanosheets with 2–5 layers were obtained under optimized exfoliation conditions using a 15 wt% glycine‐bisulfate (aqueous) solution, with working biases of +1 V and +3 V applied for 5 min. The role of the glycine‐bisulfate ionic complex in the electrochemical exfoliation process was confirmed through comparison with a control experiment using only sulfuric acid as the electrolyte. A plausible electrochemical exfoliation mechanism that involves the formation of surface molecule nuclei via the polymerization of intercalated monomeric HSO4− and SO42− ions is proposed. The ionic complex plays a key role in the anodic graphite exfoliation via electrochemical‐potential‐induced intercalation, leading to an efficient expansion of graphite sheets via the insertion of oxygen functional groups.

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Large-area high-throughput synthesis of monolayer graphene sheet by Hot Filament Thermal Chemical Vapor Deposition

Cited by 151 publications

References 58 publications

Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

Soft Processing of Graphene Nanosheets by Glycine‐Bisulfate Ionic‐Complex‐Assisted Electrochemical Exfoliation of Graphite for Reduction Catalysis

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