scholarly journals Seed-Assisted Synthesis of Graphene Films on Insulating Substrate

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1376
Author(s):  
Qiqi Zhuo ◽  
Yipeng Mao ◽  
Suwei Lu ◽  
Bolu Cui ◽  
Li Yu ◽  
...  
Keyword(s):  
Transfer Process ◽  
Large Scale ◽  
Direct Synthesis ◽  
Carbon Sources ◽  
Poly Vinyl Alcohol ◽  
Direct Production ◽  
Atomic Force ◽  
Graphene Films ◽  
Electronic Microscope ◽  
Insulating Substrates

Synthesizing graphene at a large-scale and of high quality on insulating substrate is a prerequisite for graphene applications in electronic devices. Typically, graphene is synthesized and then transferred to the proper substrate for subsequent device preparation. However, the complicated and skilled transfer process involves some issues such as wrinkles, residual contamination and breakage of graphene films, which will greatly degrade its performance. Direct synthesis of graphene on insulating substrates without a transfer process is highly desirable for device preparation. Here, we report a simple, transfer-free method to synthesize graphene directly on insulating substrates (SiO2/Si, quartz) by using a Cu layer, graphene oxide and Poly (vinyl alcohol) as the catalyst, seeds and carbon sources, respectively. Atomic force microscope (AFM), scanning electronic microscope (SEM) and Raman spectroscopy are used to characterize the interface of insulating substrate and graphene. The graphene films directly grown on quartz glass can attain a high transmittance of 92.8% and a low sheet resistance of 620 Ω/square. The growth mechanism is also revealed. This approach provides a highly efficient method for the direct production of graphene on insulating substrates.

Graphene growth on SiC and other substrates using carbon sources

2011 ◽  
Vol 1284 ◽  
Author(s):  
W. C. Mitchel ◽  
J. H. Park ◽  
Howard E. Smith ◽  
L. Grazulis ◽  
S. Mou ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Carbon Flux ◽  
Carbon Sources ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films ◽  
Additional Control ◽  
P Type ◽  
Type Conduction

ABSTRACTDirect deposition of graphene from carbon sources on foreign substrates without the use of metal catalysts is shown to be an effective process with several advantages over other growth techniques. Carbon source molecular beam epitaxy (CMBE) in particular provides an additional control parameter in carbon flux and enables growth on substrates other than SiC, including oxidized Si and sapphire. CMBE using thermally evaporated C60 and a heated graphite filament on SiC is reported here. The graphene films were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Hall effect. Graphene films on Si-face SiC grown using the C60 source have Bernal-like stacking and n-type conduction while those grown using the graphite filament have turbostratic stacking and p-type conduction. The sheet concentration for both n- and p-type doping is linearly dependent on film thickness.

Versatile Water-Based Transfer of Large-Area Graphene Films onto Flexible Substrates

MRS Advances ◽  
2017 ◽  
Vol 2 (60) ◽  
pp. 3749-3754
Author(s):  
Maria Kim ◽  
Changfeng Li ◽  
Jannatul Susoma ◽  
Juha Riikonen ◽  
Harri Lipsanen
Keyword(s):  
Transfer Process ◽  
Flexible Electronics ◽  
Large Scale ◽  
Hot Water ◽  
Polyethylene Naphthalate ◽  
Large Area ◽  
High Quality ◽  
Flexible Polymer ◽  
Graphene Films ◽  
Water Based

ABSTRACTNext-generation electronic devices are expected to demonstrate greater utility, efficiency and durability. Meanwhile, plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and variety of poly(para-xylylene) polymers enable transformational advantages to device shape, flexibility, weight, transparency and recyclability. Exhibiting a combination of outstanding mechanical, electrical, optical, and chemical properties of graphene with the plastic substrates could propose ideal material for the future flexible electronics. Chemical vapor deposition (CVD) allows cost-effective fabrication of a high-quality large-area graphene films, however, the critical issue is clean and noninvasive transfer of the films onto a desired substrate. The water-based delamination of CVD grown graphene on Cu can be considered as a “green” transfer process utilizing only hot deionized water. We investigated a method requiring only two essential steps: coating of 6-inch monolayer CVD graphene with transparent and flexible polymer, and Cu delamination in hot water. Proposed method is inexpensive, reproducible, environmentally friendly, waste-free and suitable for large-scale, high quality graphene. The transfer process demonstrated films with enhanced charge carrier mobility, high uniformity, free of mechanical defects, and sheet resistance as low as ∼50 Ω/sq with 96.5 % transparency at 550 nm wavelength.

Graphene Growth on SiC and Metal Surfaces by Solid Source Carbon Deposition

2010 ◽  
Vol 1246 ◽  
Author(s):  
W. C. Mitchel ◽  
J. H. Park ◽  
H. E. Smith ◽  
L. Grazulis
Keyword(s):  
Thermal Decomposition ◽  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Carbon Flux ◽  
Carbon Deposition ◽  
Carbon Sources ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films

AbstractGraphene has been grown by direct deposition of carbon from solid sources on both SiC and Ta films on SiC in an MBE environment. Carbon fluxes were obtained from thermally evaporated C60 and from a heated graphite filament. The graphene films were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Graphene films on Si-face SiC grown by carbon source MBE (CSMBE) were compared with graphene grown by the standard epitaxial graphene process using SiC thermal decomposition. CSMBE on SiC was found to grow at lower temperatures (1200°C) and to have fewer pits and a more uniform surface. Uniform graphene films were found to grow on Ta films after exposure to both carbon sources at 1200°C but Raman measurements showed no signs of graphene on films exposed to the same temperature without a carbon flux.

Effect of the Sulfate Concentration on the Graphene Film Produced by Electrochemical Exfoliation

2019 ◽  
Vol 290 ◽  
pp. 127-133
Author(s):  
Yu Zhang Ng ◽  
Khi Poay Beh ◽  
Faris Hidayat Ahmad Suhaimi ◽  
Raed Abdalraheem ◽  
Hwee San Lim ◽  
...  
Keyword(s):  
Large Scale ◽  
Graphene Film ◽  
Electrode System ◽  
Nanometer Scale ◽  
Sulfate Concentration ◽  
High Demand ◽  
Electrochemical Exfoliation ◽  
Exfoliated Graphene ◽  
Atomic Force ◽  
Graphene Films

Studies and production of anodic exfoliated graphene have been blossoming exponentially to meet the high demand for next generation optoelectronics devices. In this study, the effect of sulfate concentration on the graphene film is presented. The electrochemical exfoliation was conducted using a simple two-electrode system to study on the morphological and optical properties of graphene films using Atomic Force Microscope (AFM), Raman Spectroscopy and Ultraviolet–Visible (UV-Vis) spectrophotometer. Preliminary results show the presence of few layers graphene with nanometer-scale lateral dimension. The study suggests an alternative solution for the large-scale manufacturing capabilities of graphene is feasible

Evaluation of the growth and sporulation of different entomopathogenic fungi in different liquid and solid media at varied concentrations

2017 ◽  
Vol 6 (8) ◽  
pp. 5459
Author(s):  
Chandra Teja K. ◽  
Rahman S. J.
Keyword(s):  
Entomopathogenic Fungi ◽  
Large Scale ◽  
Insect Pests ◽  
Culture Media ◽  
Virulent Strain ◽  
Carbon Sources ◽  
Nitrogen Sources ◽  
Maximum Growth ◽  
Nutritional Requirements ◽  
Virulent Strains

Entomopathogenic fungi like Beauveria bassiana, Metarhizium anisopliae and Lecanicillium lecanii are used in biological control of agricultural insect pests. Their specific mode of action makes them an effective alternative to the chemical Insecticides. Virulent strains of Entomopathogenic fungi are effectively formulated and used as bio-insecticides world-wide. Amenable and economical multiplication of a virulent strain in a large scale is important for them to be useful in the field. Culture media plays a major role in the large-scale multiplication of virulent strains of Entomopathogens. Different substrates and media components are being used for this purpose. Yet, each strain differs in its nutritional requirements for the maximum growth and hence it is necessary to standardize the right components and their optimum concentrations in the culture media for a given strain of Entomopathogen. In the current study, three different nitrogen sources and two different carbon sources were tried to standardize the mass multiplication media for seven test isolates of Entomopathogenic fungi. A study was also conducted to determine the ideal grain media for the optimum conidial yields of the test isolates. Yeast extract was found to be the best Nitrogen source for the isolates. The isolates tested, differed in their nutritional requirements and showed variation in the best nitrogen and carbon sources necessary for their growth. Variation was also found in the optimum concentration of both the ingredients for the growth and sporulation of the isolates. In the solid-state fermentation study, rice was found to be the best grain for the growth of most of the fungi followed by barley. The significance of such a study in the development of an effective Myco-insecticide is vital and can be successfully employed in agriculture is discussed.

scholarly journals Large-Scale Analysis of the Spatiotemporal Changes of Net Ecosystem Production in Hindu Kush Himalayan Region

2021 ◽  
Vol 13 (6) ◽  
pp. 1180
Author(s):  
Da Guo ◽  
Xiaoning Song ◽  
Ronghai Hu ◽  
Xinming Zhu ◽  
Yazhen Jiang ◽  
...  
Keyword(s):  
Large Scale ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Carbon Sources ◽  
Spatial Dynamics ◽  
Tibet Plateau ◽  
Geostatistical Model ◽  
Hindu Kush ◽  
Temporal And Spatial ◽  
The Difference

The Hindu Kush Himalayan (HKH) region is one of the most ecologically vulnerable regions in the world. Several studies have been conducted on the dynamic changes of grassland in the HKH region, but few have considered grassland net ecosystem productivity (NEP). In this study, we quantitatively analyzed the temporal and spatial changes of NEP magnitude and the influence of climate factors on the HKH region from 2001 to 2018. The NEP magnitude was obtained by calculating the difference between the net primary production (NPP) estimated by the Carnegie–Ames Stanford Approach (CASA) model and the heterotrophic respiration (Rh) estimated by the geostatistical model. The results showed that the grassland ecosystem in the HKH region exhibited weak net carbon uptake with NEP values of 42.03 gC∙m−2∙yr−1, and the total net carbon sequestration was 0.077 Pg C. The distribution of NEP gradually increased from west to east, and in the Qinghai–Tibet Plateau, it gradually increased from northwest to southeast. The grassland carbon sources and sinks differed at different altitudes. The grassland was a carbon sink at 3000–5000 m, while grasslands below 3000 m and above 5000 m were carbon sources. Grassland NEP exhibited the strongest correlation with precipitation, and it had a lagging effect on precipitation. The correlation between NEP and the precipitation of the previous year was stronger than that of the current year. NEP was negatively correlated with temperature but not with solar radiation. The study of the temporal and spatial dynamics of NEP in the HKH region can provide a theoretical basis to help herders balance grazing and forage.

scholarly journals Long Low-Loss-Litium Niobate on Insulator Waveguides with Sub-Nanometer Surface Roughness

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 910 ◽  
Author(s):  
Rongbo Wu ◽  
Min Wang ◽  
Jian Xu ◽  
Jia Qi ◽  
Wei Chu ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Integrated Circuits ◽  
Large Scale ◽  
Photonic Integrated Circuits ◽  
Surface Patterning ◽  
Propagation Loss ◽  
Direct Writing ◽  
Laser Direct Writing ◽  
Low Loss ◽  
Atomic Force

In this paper, we develop a technique for realizing multi-centimeter-long lithium niobate on insulator (LNOI) waveguides with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium thin film coated on the top surface of LNOI into a hard mask with a femtosecond laser followed by chemo-mechanical polishing for structuring the LNOI into the waveguides. The surface roughness on the waveguides was determined with an atomic force microscope to be 0.452 nm. The approach is compatible with other surface patterning technologies, such as optical and electron beam lithographies or laser direct writing, enabling high-throughput manufacturing of large-scale LNOI-based photonic integrated circuits.

Large-scale nanoelectromechanical switches based on directly deposited nanocrystalline graphene on insulating substrates

Nanoscale ◽  
2016 ◽  
Vol 8 (12) ◽  
pp. 6659-6665 ◽  
Author(s):  
Jian Sun ◽  
Marek E. Schmidt ◽  
Manoharan Muruganathan ◽  
Harold M. H. Chong ◽  
Hiroshi Mizuta
Keyword(s):  
Large Scale ◽  
Insulating Substrates

scholarly journals Natural Carbon Nanodots: Toxicity Assessment and Theranostic Biological Application

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1874
Author(s):  
Ming-Hsien Chan ◽  
Bo-Gu Chen ◽  
Loan Thi Ngo ◽  
Wen-Tse Huang ◽  
Chien-Hsiu Li ◽  
...  
Keyword(s):  
Carbon Source ◽  
Large Scale ◽  
New Technologies ◽  
Cell Damage ◽  
Carbon Sources ◽  
Diagnosis And Treatment ◽  
Carbon Nanodots ◽  
Biological Application ◽  
Treatment Research ◽  
Natural Carbon

This review outlines the methods for preparing carbon dots (CDs) from various natural resources to select the process to produce CDs with the best biological application efficacy. The oxidative activity of CDs mainly involves photo-induced cell damage and the destruction of biofilm matrices through the production of reactive oxygen species (ROS), thereby causing cell auto-apoptosis. Recent research has found that CDs derived from organic carbon sources can treat cancer cells as effectively as conventional drugs without causing damage to normal cells. CDs obtained by heating a natural carbon source inherit properties similar to the carbon source from which they are derived. Importantly, these characteristics can be exploited to perform non-invasive targeted therapy on human cancers, avoiding the harm caused to the human body by conventional treatments. CDs are attractive for large-scale clinical applications. Water, herbs, plants, and probiotics are ideal carbon-containing sources that can be used to synthesize therapeutic and diagnostic CDs that have become the focus of attention due to their excellent light stability, fluorescence, good biocompatibility, and low toxicity. They can be applied as biosensors, bioimaging, diagnosis, and treatment applications. These advantages make CDs attractive for large-scale clinical application, providing new technologies and methods for disease occurrence, diagnosis, and treatment research.

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