scholarly journals Atmospheric Pressure Catalytic Vapor Deposition of Graphene on Liquid In and Cu-In Alloy Substrates

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1318
Author(s):  
Maryam A. Saeed ◽  
Ian A. Kinloch ◽  
Brian Derby
Keyword(s):  
Atmospheric Pressure ◽  
Defect Density ◽  
Growth Parameters ◽  
Chemical Vapour ◽  
Growth Conditions ◽  
Growth Time ◽  
Graphene Growth ◽  
Graphene Films ◽  
Reactive Gases

Liquid substrates are great candidates for the growth of high-quality graphene using chemical vapour deposition (CVD) due to their atomically flat and defect free surfaces. A detailed study of graphene growth using atmospheric pressure CVD (APCVD) on liquid indium (In) was conducted. It was found that the effect of the growth parameters on the quality of the graphene produced is highly dependent on the properties of the substrate used. A short residence time of 6.8 sec for the reactive gases led to a high graphene quality, indicating the good catalytic behaviour of In. The role of hydrogen partial pressure was found to be crucial, with monolayer and bilayer graphene films with a low defect density obtained at low PH2 (38.6 mbar), whilst more defective, thicker graphene films with a partial coverage being obtained at high PH2 (74.3 mbar). The graphene deposition was insensitive to growth time as the graphene growth on liquid In was found to self-limit to bilayer. For further investigation, five compositions of Cu-In alloys were made by arc-melting. Graphene was then grown using the optimum conditions for In and the quality of the graphene was found to degrade with increasing Cu wt.%. This work will aid the future optimisation of the growth conditions based upon the substrate’s properties.

The Effects of Reaction Temperature on the Morphology and the Quality of the Carbon Nanotube - Silica Microparticles

2016 ◽  
Vol 1133 ◽  
pp. 467-470
Author(s):  
Raja Nor Othman ◽  
Arthur N. Wilkinson
Keyword(s):  
Carbon Nanotube ◽  
Reaction Temperature ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Growth Conditions ◽  
Growth Time ◽  
Hybrid Particles ◽  
Spherical Silica ◽  
Silica Microparticles

Carbon nanotube has been successfully grafted on the surface of spherical silica gel via floating-catalyst chemical vapour deposition method. The growth conditions were set to be 3 hours growth time and 5 wt. % of ferrocene catalyst (dissolved in toluene) injected into the furnace at a rate of 0.04 ml/min. It was found that the reaction temperature of 760°C yields the best quality hybrid particles. Decreasing and increasing the reaction temperature resulted in the formation of product that consists of thicker tubes, higher defects as analysed by Raman, as well as least carbon formation.

Influence of Diamond CVD Growth Conditions and Interlayer Material on Diamond/GaN Interface

2015 ◽  
Vol 821-823 ◽  
pp. 982-985 ◽  
Author(s):  
Tibor Izak ◽  
Oleg Babchenko ◽  
Vít Jirásek ◽  
Gabriel Vanko ◽  
Marián Vojs ◽  
...  
Keyword(s):  
Diamond Film ◽  
Film Formation ◽  
Diamond Films ◽  
Chemical Vapour ◽  
Growth Conditions ◽  
High Ratio ◽  
Cvd Growth ◽  
Chemical Character ◽  
Thin Interlayer

In this study we present the diamond deposition on AlGaN/GaN substrates focusing on the quality of the diamond/GaN interface. The growth of diamond films was performed using microwave chemical vapour deposition system in different gas mixtures: standard CH4/H2(at low and high ratio of CH4to H2) and addition of CO2to CH4/H2gas chemistry. The diamond films were grown directly on GaN films either without or with thin interlayer. As interlayer, 100 nm thick Si3N4was used. Surprisingly, in the case of standard CH4/H2gas mixture, no diamond film was observed on the GaN with SiN interlayer, while adding of CO2resulted in diamond film formation of both samples with and without SiN interlayer. Moreover, adding of CO2led to higher growth rate. The morphology of diamond films and the quality of the diamond/GaN interface was investigated from the cross-section images by scanning electron microscopy and the chemical character (i.e. sp3versus sp2carbon bonds) was measured by Raman spectroscopy.

scholarly journals Atmospheric Pressure Catalytic Vapor Deposition of Graphene on Liquid Sn and Cu–Sn Alloy Substrates

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2150
Author(s):  
Maryam A. Saeed ◽  
Ian A. Kinloch ◽  
Brian Derby
Keyword(s):  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Defect Density ◽  
Chemical Vapor ◽  
Hydrogen Solubility ◽  
Monolayer Graphene ◽  
High Catalytic Activity ◽  
Graphene Growth ◽  
Hydrogen Flow

The chemical vapor deposition (CVD) of graphene on liquid substrates produces high quality graphene films due to the defect-free and atomically flat surfaces of the liquids. Through the detailed study of graphene growth on liquid Sn using atmospheric pressure CVD (APCVD), the quality of graphene has been found to have a close relationship with hydrogen flow rate that reflects on hydrogen partial pressure inside the reactor (PH2) and hydrogen solubility of the growth substrates. The role of PH2 was found to be crucial, with a low defect density monolayer graphene being obtained in low PH2 (90.4 mbar), while partial graphene coverage occurred at high PH2 (137.3 mbar). To further understand the role of substrate’s composition, binary alloy with compositions of 20, 30, 50, 60 and 80 wt.% tin in copper were made by arc-melting. Graphene quality was found to decrease with increasing the content of copper in the Cu–Sn alloys when grown using the conditions optimised for Sn substrates and this was related to the change in hydrogen solubility and the high catalytic activity of Cu compared to Sn. This shall provide a tool to help optimising CVD conditions for graphene growth based on the properties of the used catalytic substrate.

Heteroepitaxy of Si, Ge, and GaAs Films on CaF2/Si Structures

1986 ◽  
Vol 67 ◽  
Author(s):  
H. Ishiwara ◽  
T. Asano ◽  
H. C. Lee ◽  
Y. Kuriyama ◽  
K. Seki ◽  
...  
Keyword(s):  
Smooth Surface ◽  
Field Effect Transistors ◽  
Growth Parameters ◽  
Growth Conditions ◽  
Heteroepitaxial Growth ◽  
Gate Electrodes ◽  
Gaas Films ◽  
Temperature And Growth ◽  
Si Films

ABSTRACTRecent progress in the research of heteroepitaxial growth of Si, Ge, and GaAs films on CaF2/Si structures is reviewed. Growth conditions and material properties of the Si/CaF2/Si structures are first discussed. It is shown that such growth techniques as the predeposition technique and the recrystallization method are useful to improve the crystalline quality of Si films on the CaF2/Si structures. Then, device application of the Si/CaF2/Si structure to field effect transistors with epitaxial MIS (metal-insulatorsemiconductor) gate electrodes is described. Finally, epitaxial growth of Ge and GaAs films on the CaF2/Si structure are discussed, in which such growth parameters as the substrate temperature and growth rate are optimized to obtain high-quality films with excellent crystallinity and smooth surface.

The role of mixed cubic/hexagonal nucleation layers on threading dislocation reduction in epitaxial GaN films

1996 ◽  
Vol 54 ◽  
pp. 646-647
Author(s):  
X. H. Wu ◽  
L. M. Brown ◽  
D. Kapolnek ◽  
S. Kellert ◽  
B. Kellert ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Flow Reactor ◽  
Defect Density ◽  
Threading Dislocation ◽  
Growth Substrate ◽  
Dislocation Reduction ◽  
Reactor Operating ◽  
Gan Buffer Layer

The defect density and their configuration in epitaxial GaN films on sapphire are strongly related to the optical and electrical properties of the films. The crystalline quality of GaN on sapphire can be greatly improved by introducing a low temperature GaN buffer layer. However, recent studies in our group demonstrate that the pre-growth substrate treatment can significantly change the defects structure and electron properties of the films. In this paper, we present our results on studies of the film microstructures and their corresponding nucleation layers. We propose a novel mechanism for dislocation reduction for GaN on sapphire.The growths for this study were achieved in a horizontal flow reactor operating at atmospheric pressure. Basal plane AI2O3 (Union Carbide) substrates were first cleaned in solvents and then heated in flowing H2 at 1050°C. Sample A was exposed to an ammonia flow of 3 1/min for 60s, sample B for 400s before the temperature was then reduced to 600°C and a nominal 190 Å thick GaN layer was grown.

scholarly journals Flexible and monolithically integrated multicolor light emitting diodes using morphology-controlled GaN microstructures grown on graphene films

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Keundong Lee ◽  
Dongha Yoo ◽  
Hongseok Oh ◽  
Gyu-Chul Yi
Keyword(s):  
Mechanical Stability ◽  
Growth Parameters ◽  
Light Emitting Diode ◽  
Growth Time ◽  
Controlled Growth ◽  
Light Emitting ◽  
Cvd Graphene ◽  
Monolithically Integrated ◽  
Graphene Films ◽  
Led Arrays

AbstractWe report flexible and monolithically integrated multicolor light-emitting diode (LED) arrays using morphology-controlled growth of GaN microstructures on chemical-vapor-deposited (CVD) graphene films. As the morphology-controlled growth template of GaN microstructures, we used position-controlled ZnO nanostructure arrays with different spacings grown on graphene substrates. In particular, we investigated the effect of the growth parameters, including micropattern spacings and growth time and temperature, on the morphology of the GaN microstructures when they were coated on ZnO nanostructures on graphene substrates. By optimizing the growth parameters, both GaN microrods and micropyramids formed simultaneously on the graphene substrates. Subsequent depositions of InGaN/GaN quantum well and p-GaN layers and n- and p-type metallization yielded monolithic integration of microstructural LED arrays on the same substrate, which enabled multicolor emission depending on the shape of the microstructures. Furthermore, the CVD graphene substrates beneath the microstructure LEDs facilitated transfer of the LED arrays onto any foreign substrate. In this study, Cu foil was used for flexible LEDs. The flexible devices exhibited stable electroluminescence, even under severe bending conditions. Cyclic bending tests demonstrated the excellent mechanical stability and reliability of the devices.

Growth Conditions of Erbium-Oxygen-Doped Silicon Grown by MBE

1996 ◽  
Vol 422 ◽  
Author(s):  
J. Stimmer ◽  
A. Reittinger ◽  
G. Abstreiter ◽  
H. Holzbrecher ◽  
Ch. Buchal
Keyword(s):  
Molecular Beam Epitaxy ◽  
Systematic Study ◽  
Molecular Beam ◽  
Growth Parameters ◽  
Light Emitting Diode ◽  
Growth Conditions ◽  
Light Emitting ◽  
Doped Silicon

AbstractWe report on a systematic study of the growth parameters of erbium-oxygen-doped silicon grown by molecular beam epitaxy. The surface quality of the grown layers was measured in situ by RHEED. The samples were characterized by photoluminescence measurements and SIMS. An Er-O-doped Si light emitting diode grown with the optimized parameters is presented.

Impurity Effects in the Growth of 4H-SiC Crystals by Physical Vapor Transport

1999 ◽  
Vol 572 ◽  
Author(s):  
V. Balakrishna ◽  
G. Augustine ◽  
R. H. Hopkins
Keyword(s):  
Electronic Device ◽  
Defect Density ◽  
Growth Parameters ◽  
Large Diameter ◽  
Growth Conditions ◽  
High Resistivity ◽  
Growth Surface ◽  
Second Phase ◽  
Impurity Effects ◽  
Growth Environment

ABSTRACTSiC is an important wide bandgap semiconductor material for high temperature and high power electronic device applications. Purity improvements in the growth environment has resulted in a two-fold benefit during growth: (a) minimized inconsistencies in the background doping resulting in high resistivity (>5000 ohm-cm) wafer yield increase from 10–15% to 70-85%, and (b) decrease in micropipe formation. Growth parameters play an important role in determining the perfection and properties of the SiC crystals, and are extremely critical in the growth of large diameter crystals. Several aspects of growth are vital in obtaining highly perfect, large diameter crystals, such as: (i) optimized furnace design, (ii) high purity growth environment, and (iii) carefully controlled growth conditions. Although significant reduction in micropipe density has been achieved by improvements in the growth process, more stringent device requirements mandate further reduction in the defect density. In-depth understanding of the mechanisms of micropipe formation is essential in order to devise approaches to eliminate them. Experiments have been performed to understand the role of growth conditions and ambient purity on crystal perfection by intentionally introducing arrays of impurity sites on one half of the growth surface. Results clearly suggest that presence of impurities or second phase inclusions during start or during growth can result in the nucleation of micropipes. Insights obtained from these studies were instrumental in the growth of ultra-low micropipe density (less than 2 micropipes cm−2 ) in 1.5 inch diameter boules.

scholarly journals 3C-SiС Hetero-Epitaxially Grown on Silicon Compliance Substrates and New 3C-SiС Substrates for Sustainable Wide-Band-Gap Power Devices (CHALLENGE)

2018 ◽  
Vol 924 ◽  
pp. 913-918 ◽  
Author(s):  
Francesco La Via ◽  
Fabrizio Roccaforte ◽  
Antonino La Magna ◽  
Roberta Nipoti ◽  
Fulvio Mancarella ◽  
...  
Keyword(s):  
Band Gap ◽  
Defect Density ◽  
Narrow Band ◽  
Wide Band ◽  
Growth Conditions ◽  
Power Devices ◽  
Wide Band Gap ◽  
New Material ◽  
Numerical Tools

The cubic polytype of SiC (3C-SiC) is the only one that can be grown on silicon substrate with the thickness required for targeted applications. Possibility to grow such layers has remained for a long period a real advantage in terms of scalability. Even the relatively narrow band-gap of 3C-SiC (2.3eV), which is often regarded as detrimental in comparison with other polytypes, can in fact be an advantage. However, the crystalline quality of 3C-SiC on silicon has to be improved in order to benefit from the intrinsic 3C-SiC properties. In this project new approaches for the reduction of defects will be used and new compliance substrates that can help to reduce the stress and the defect density at the same time will be explored. Numerical simulations will be applied to optimize growth conditions and reduce stress in the material. The structure of the final devices will be simulated using the appropriated numerical tools where new numerical model will be introduced to take into account the properties of the new material. Thanks to these simulations tools and the new material with low defect density, several devices that can work at high power and with low power consumption will be realized within the project.

scholarly journals Time-dependent evolution of the nitrogen configurations in N-doped graphene films

RSC Advances ◽  
2016 ◽  
Vol 6 (108) ◽  
pp. 106914-106920 ◽  
Author(s):  
Boitumelo J. Matsoso ◽  
Kamalakannan Ranganathan ◽  
Bridget K. Mutuma ◽  
Tsenolo Lerotholi ◽  
Glenn Jones ◽  
...  
Keyword(s):  
Chemical Vapour Deposition ◽  
Atmospheric Pressure ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Time Dependent ◽  
Large Area ◽  
Graphene Films ◽  
Pressure Chemical ◽  
Doped Graphene ◽  
Cu Foil

Large-area time-controlled N-doped graphene films were grown on a Cu foil using an ammonia-assisted atmospheric pressure chemical vapour deposition (APCVD) technique.

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