Microwave plasma-based direct synthesis of free-standing N-graphene

2020 ◽  
Vol 22 (8) ◽  
pp. 4772-4787 ◽  
Author(s):  
D. Tsyganov ◽  
N. Bundaleska ◽  
A. Dias ◽  
J. Henriques ◽  
E. Felizardo ◽  
...  
Keyword(s):  
Microwave Plasma ◽  
Direct Synthesis ◽  
Plasma Zone ◽  
Free Standing ◽  
Ammonia Plasma

Scheme of ethanol/ammonia plasma driven decomposition pathways considering injection of the nitrogen precursor in “hot” and “mild” plasma zone.

Direct synthesis of beta gallium oxide nanowires, nanobelts, nanosheets and nanograsses by microwave plasma

2006 ◽  
Vol 137 (4) ◽  
pp. 177-181 ◽  
Author(s):  
Feng Zhu ◽  
Zhong Xue Yang ◽  
Wei Min Zhou ◽  
Ya Fei Zhang
Keyword(s):  
Gallium Oxide ◽  
Microwave Plasma ◽  
Direct Synthesis ◽  
Oxide Nanowires

Nanocrystalline Diamond as a Dielectric for SOD Applications

2007 ◽  
Vol 1039 ◽  
Author(s):  
Mose Bevilacqua ◽  
Niall Tumilty ◽  
Aysha Chaudhary ◽  
Haitao Ye ◽  
James E Butler ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Microwave Plasma ◽  
Chemical Vapour ◽  
Polycrystalline Diamond ◽  
Growth Conditions ◽  
Nanocrystalline Diamond ◽  
Free Standing ◽  
Single Crystal Diamond

AbstractNanocrystalline diamond (NCD) has been grown on oxide coated silicon wafers by microwave plasma assisted chemical vapour deposition using a novel seeding technique followed by optimised growth conditions, and leads to a highly-dense form of this material with grain sizes around 100nm for films approximately 1.5 microns thick. The electrical properties of these films have been investigated using Impedance Spectroscopy, which enables the contributions from sources characterised by differing capacitances, such as grain boundaries and grain interiors, to be isolated. After an initial acid clean the electrical properties of the film are not stable, and both grain boundaries and grains themselves contribute to the frequency dependant impedance values recorded. However, following mild oxidation grain boundary conduction is completely removed and the films become highly resistive (>1013 ohm/sq). This is most unusual, as conduction through NCD material is more normally dominated by grain boundary effects. Interestingly, the AC properties of these films are also excellent with a dielectric loss value (tan δ) as low as 0.002 for frequencies up to 10MHz. The dielectric properties of these NCD films are therefore as good as high quality free-standing (large grain) polycrystalline diamond films, and not too dissimilar to single crystal diamond, and are therefore ideally suited to future ‘silicon-on-diamond’ applications.

Direct Synthesis of Vertically Interconnected 3-D Graphitic Nanosheets on Hemispherical Carbon Particles by Microwave Plasma CVD

Plasmonics ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Jitendra N. Tiwari ◽  
Rajanish N. Tiwari ◽  
Gyan Singh ◽  
Kun-Lin Lin
Keyword(s):  
Microwave Plasma ◽  
Direct Synthesis ◽  
Plasma Cvd ◽  
Carbon Particles ◽  
Microwave Plasma Cvd

The mechanical Properties of CVD Diamond Films, and Diamond Coated Fibres and Wires

1995 ◽  
Vol 383 ◽  
Author(s):  
E D Nicholson ◽  
J E Field ◽  
P G Partridge ◽  
M N R Ashfold
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Microwave Plasma ◽  
Young's Modulus ◽  
Protective Coatings ◽  
Small Diameter ◽  
Cvd Diamond ◽  
Film Stress ◽  
Free Standing ◽  
Film Property

ABSTRACTTwo areas of thin film property measurement are addressed. The first is that of flat films, either on a substrate or free-standing. The film properties only are of interest. Therefore, when the film remains attached to a substrate during testing, an appropriate analysis is used to subtract the effect of the substrate. The films under test are prospective protective coatings and ‘window’ materials for infrared applications, namely CVD diamond (Hot filament Assisted, HFACVD and Microwave plasma assisted, MPACVD) and Germanium carbide (Ge:C). The mechanical properties under investigation are the Young's modulus and the internal film stress.In the second case the substrates are small diameter fibres and wires coated with CVD diamond. The mechanical properties measured were composite, containing contributions from both the substrate and the film. These coated fibres and wires, have possible applications as reinforcement phases in the production of composites. They are silicon carbide (SiC) and Tungsten (W) of diameters varying between 10 and 125μm. A technique has been developed to measure the Young's modulus of individual coated fibres.

scholarly journals Subtractive Low-Temperature Preparation Route for Porous SiO2 Used for the Catalyst-Assisted Growth of ZnO Field Emitters

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3357
Author(s):  
Stefanie Haugg ◽  
Carina Hedrich ◽  
Robert H. Blick ◽  
Robert Zierold
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Silicon Oxide ◽  
Direct Synthesis ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Free Standing ◽  
Field Emitters ◽  
Low Temperature Preparation ◽  
Preparation Route

The possibility to gradually increase the porosity of thin films facilitates a variety of applications, such as anti-reflective coatings, diffusion membranes, and the herein investigated tailored nanostructuring of a substrate for subsequent self-assembly processes. A low-temperature (<160 °C) preparation route for porous silicon oxide (porSiO2) thin films with porosities of about 60% and effective refractive indices down to 1.20 is tailored for bulk as well as free-standing membranes. Subsequently, both substrate types are successfully employed for the catalyst-assisted growth of nanowire-like zinc oxide (ZnO) field emitters by metal organic chemical vapor deposition. ZnO nanowires can be grown with a large aspect ratio and exhibit a good thermal and chemical stability, which makes them excellent candidates for field emitter arrays. We present a method that allows for the direct synthesis of nanowire-like ZnO field emitters on free-standing membranes using a porSiO2 template. Besides the application of porSiO2 for the catalyst-assisted growth of nanostructures and their use as field emission devices, the herein presented general synthesis route for the preparation of low refractive index films on other than bulk substrates—such as on free-standing, ultra-thin membranes—may pave the way for the employment of porSiO2 in micro-electro-mechanical systems.

Infrared optical properties of CVD diamond films

1990 ◽  
Vol 5 (11) ◽  
pp. 2345-2350 ◽  
Author(s):  
X. H. Wang ◽  
L. Pilione ◽  
W. Zhu ◽  
W. Yarbrough ◽  
W. Drawl ◽  
...  
Keyword(s):  
Optical Properties ◽  
Microwave Plasma ◽  
Crystalline Silicon ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Optical Absorption Coefficient ◽  
Wave Number ◽  
Silicon Substrates ◽  
Free Standing ◽  
Infrared Optical Properties

Diamond films of 15–20 μm thicknesses were prepared by microwave plasma enhanced chemical vapor deposition onto crystalline silicon substrates. The growth surfaces of the films were rough with polycrystalline crystallographic habits, while the substrate sides of these films were smooth and featureless as viewed by optical microscopy. A heated cast iron scaife was used to polish the rough growth surfaces, and free-standing films were removed from the silicon substrates by dissolving the silicon in an aqueous HF. Both infrared optical transmission and reflection spectra were measured over the range of 600–4000 cm−1. For polished films, near 70% transmittance was obtained over the whole range, while the transmittance for nonpolished films was much lower and varied strongly with the wave number. Absorptions due to carbon-hydrogen stretching bands as well as a silicon carbide phase were observed in the transmission spectra. The optical absorption coefficient and the refractive index were found to vary from as high as 150 to as low as 7 cm−1 and 2.41 to 2.49, respectively (depending on the film quality and the wave number). A weak signature of the two-phonon absorption band of diamond was observed. The relationship between deposition conditions and infrared optical properties of diamond films before as well as after polishing is discussed.

scholarly journals Direct Synthesis of Large-Area Graphene on Insulating Substrates at Low Temperature using Microwave Plasma CVD

ACS Omega ◽  
2019 ◽  
Vol 4 (6) ◽  
pp. 11263-11270 ◽  
Author(s):  
Riteshkumar Vishwakarma ◽  
Rucheng Zhu ◽  
Amr Attia Abuelwafa ◽  
Yota Mabuchi ◽  
Sudip Adhikari ◽  
...  
Keyword(s):  
Low Temperature ◽  
Microwave Plasma ◽  
Direct Synthesis ◽  
Plasma Cvd ◽  
Large Area ◽  
Microwave Plasma Cvd ◽  
Insulating Substrates

scholarly journals Simultaneous Synthesis and Nitrogen Doping of Free-Standing Graphene Applying Microwave Plasma

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4213
Author(s):  
D. Tsyganov ◽  
N. Bundaleska ◽  
J. Henriques ◽  
E. Felizardo ◽  
A. Dias ◽  
...  
Keyword(s):  
Microwave Plasma ◽  
Optical Emission ◽  
Single Step ◽  
Gas Temperature ◽  
Step Method ◽  
Free Standing ◽  
Theoretical Predictions ◽  
Reactor Geometry ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

An experimental and theoretical investigation on microwave plasma-based synthesis of free-standing N-graphene, i.e., nitrogen-doped graphene, was further extended using ethanol and nitrogen gas as precursors. The in situ assembly of N-graphene is a single-step method, based on the introduction of N-containing precursor together with carbon precursor in the reactive microwave plasma environment at atmospheric pressure conditions. A previously developed theoretical model was updated to account for the new reactor geometry and the nitrogen precursor employed. The theoretical predictions of the model are in good agreement with all experimental data and assist in deeper understanding of the complicated physical and chemical process in microwave plasma. Optical Emission Spectroscopy was used to detect the emission of plasma-generated ‘‘building units’’ and to determine the gas temperature. The outlet gas was analyzed by Fourier-Transform Infrared Spectroscopy to detect the generated gaseous by-products. The synthesized N-graphene was characterized by Scanning Electron Microscopy, Raman, and X-ray photoelectron spectroscopies.

Microwave plasma enabled synthesis of free standing carbon nanostructures at atmospheric pressure conditions

2018 ◽  
Vol 20 (20) ◽  
pp. 13810-13824 ◽  
Author(s):  
N. Bundaleska ◽  
D. Tsyganov ◽  
A. Dias ◽  
E. Felizardo ◽  
J. Henriques ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Carbon Nanostructures ◽  
Microwave Plasma ◽  
Chemical Processes ◽  
Free Standing ◽  
Schematic Representation ◽  
Plasma Environment ◽  
Physico Chemical

Schematic representation of the physico-chemical processes involved in the formation of carbon nanostructures in the microwave plasma environment.

MICROSTRUCTURE AND MECHANICAL PROPERTY CHARACTERIZATION OF MULTILAYER FREE-STANDING DIAMOND/Mo FILMS

2019 ◽  
Vol 27 (02) ◽  
pp. 1950100
Author(s):  
LIANGLIANG LI ◽  
HONGJUN HEI ◽  
YONG MA ◽  
KE ZHENG ◽  
JIE GAO ◽  
...  
Keyword(s):  
Grain Size ◽  
Fracture Strength ◽  
Diamond Film ◽  
Microwave Plasma ◽  
Chemical Vapor ◽  
Film System ◽  
Free Standing ◽  
Columnar Crystal ◽  
Plasma Chemical Vapor Deposition ◽  
Glow Plasma

The monolayer diamond film and free-standing diamond/Mo multilayer films were prepared by combining microwave plasma chemical vapor deposition (MPCVD) and double glow plasma surface alloying (DGPSA) techniques. The result shows that the film grain size decreases from 70–80[Formula: see text][Formula: see text]m to [Formula: see text]–20[Formula: see text][Formula: see text]m with the layer number increasing from the monolayer diamond film with a columnar crystal structure to the seven-layer diamond/Mo films, indicating that the Mo interlayer can effectively reduce the grain size. The Mo2C is formed between the Mo and diamond layers, which can improve the bonding strength. The internal stress of these films depends on the number of Mo interlayers and the Mo2C content. Moreover, the fracture strength and abrasion ratio of multilayer diamond films are effectively improved by adding the Mo interlayer. The four-layer diamond/Mo film system has the highest fracture strength and the seven-layer film system has the highest abrasion ratio.

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