Kinetic Modeling of Ammonia Decomposition at CVD Conditions

2020 ◽  
Author(s):  
Karl Rönnby ◽  
Henrik Pedersen ◽  
Lars Ojamäe
Keyword(s):  
Kinetic Modeling ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Metal Nitrides ◽  
Decomposition Products ◽  
Rapid Decomposition ◽  
Wide Range ◽  
Carrier Gases ◽  
Decomposition Chemistry ◽  
Metal Ratios

Kinetic modeling has been used to study the decomposition chemistry of ammonia at a wide range of temperatures, pressures, concentrations, and carrier gases mimicking the conditions in chemical vapor deposition (CVD) of metal nitrides. The modeling show that only a small fraction of the ammonia molecules will decompose at most conditions studied. This suggests that the high NH<sub>3</sub> to metal ratios often employed in CVD is due to the very low amount of reactive decomposition products rather than due to rapid decomposition of ammonia into stable dinitrogen and dihydrogen as suggested by purely thermodynamic models.

Kinetic Modeling of Ammonia Decomposition at CVD Conditions

2020 ◽  
Author(s):  
Karl Rönnby ◽  
Henrik Pedersen ◽  
Lars Ojamäe
Keyword(s):  
Kinetic Modeling ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Metal Nitrides ◽  
Decomposition Products ◽  
Rapid Decomposition ◽  
Wide Range ◽  
Carrier Gases ◽  
Decomposition Chemistry ◽  
Metal Ratios

Kinetic modeling has been used to study the decomposition chemistry of ammonia at a wide range of temperatures, pressures, concentrations, and carrier gases mimicking the conditions in chemical vapor deposition (CVD) of metal nitrides. The modeling show that only a small fraction of the ammonia molecules will decompose at most conditions studied. This suggests that the high NH<sub>3</sub> to metal ratios often employed in CVD is due to the very low amount of reactive decomposition products rather than due to rapid decomposition of ammonia into stable dinitrogen and dihydrogen as suggested by purely thermodynamic models.

scholarly journals Fabrication of Low-Fouling Surfaces on Alkyne-Functionalized Poly-(p-xylylenes) Using Click Chemistry

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 225
Author(s):  
Pei-Ju Chen ◽  
Hsien-Yeh Chen ◽  
Wei-Bor Tsai
Keyword(s):  
Thin Films ◽  
Conjugated Polymers ◽  
Click Chemistry ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Universal Method ◽  
Surface Immobilization ◽  
Poly Ethylene Glycol ◽  
Wide Range ◽  
Poly Ethylene

A facial, versatile, and universal method that breaks the substrate limits is desirable for antifouling treatment. Thin films of functional poly-p-xylylenes (PPX) that are deposited using chemical vapor deposition (CVD) provide a powerful platform for surface immobilization of molecules. In this study, we prepared an alkyne-functionalized PPX coating on which poly (sulfobetaine methacrylate-co-Az) could be conjugated via click chemistry. We found that the conjugated polymers were very stable and inhibited cell adhesion and protein adsorption effectively. The same conjugation strategy could also be applied to conjugate azide-containing poly (ethylene glycol) and poly (NIPAAm). The results indicate that our method provides a simple and robust tool for fabricating antifouling surfaces on a wide range of substrates using CVD technology of functionalized poly (p-xylylenes) for biosensor, diagnostics, immunoassay, and other biomaterial applications.

Domain size, layer number and morphology control for graphene grown by chemical vapor deposition

2017 ◽  
Vol 10 (04) ◽  
pp. 1730003 ◽  
Author(s):  
Ruiwen Xue ◽  
Irfan H. Abidi ◽  
Zhengtang Luo
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Domain Size ◽  
Past Research ◽  
Production Methods ◽  
The Past ◽  
Number Of Layers ◽  
Size Number ◽  
Wide Range

Over the past a few years, high-quality graphene preparation has been evolved from low-yield micromechanical exfoliation in including a wide range of production methods, in particular by chemical vapor deposition (CVD). Here, we review the state-of-the-art on synthesis of graphene using CVD method and the strategies to control the graphene grain size, number of layers and morphology, mainly focusing on the graphene growth that uses Cu as substrate. We highlight the success of the past research in the field and provide a review of the methods that were used for such controlled synthesis.

Nanostructured Nickel Oxide Films Prepared by Chemical Vapor Deposition and Their Electrochromic Properties

2008 ◽  
Vol 8 (5) ◽  
pp. 2703-2706 ◽  
Author(s):  
J. R. Vargas Garcia ◽  
E. M. Lazcano Ugalde ◽  
F. Hernandez Santiago ◽  
J. M. Hallen Lopez
Keyword(s):  
Chemical Vapor Deposition ◽  
Nickel Oxide ◽  
Vapor Deposition ◽  
Near Infrared ◽  
Chemical Vapor ◽  
Optical Transmittance ◽  
Structural Features ◽  
Electrochromic Properties ◽  
Wide Range ◽  
Nio Films

The influence of the deposition conditions on the structural features and electrochromic properties of nickel oxide (NiO) films prepared by chemical vapor deposition has been investigated. NiO films have been prepared on fluorine doped tin oxide (FTO) coated glass substrates from nickel-acetylacetonate precursor and their electrochromic properties have been studied by cyclic voltammetry in a 0.1 M KOH solution at room temperature. Films exhibiting only the NiO phase were obtained at deposition temperatures higher than 450 °C in a wide range of reactor pressures (0.13 to 66.6 kPa). Particularly, NiO films prepared at 500–550 °C from 0.13 to 53.3 kPa are transparent in nature and exhibit a crystallite size varying from 10 to 60 nm. An appreciable anodic electrochromic change from transparent to black coloured resulted from a very porous surface morphology and film thickness of about 3.5 μm. The electrochromic change was maintained over 3000 switching cycles. Nanostructured 3.5 μm-thick NiO films showed a maximum difference in optical transmittance of about 40% in the near-infrared region. These results make the nanostructured NiO films comparables with those prepared by other deposition techniques.

scholarly journals Direct Synthesis of Oxynitride Nanowires through Atmospheric Pressure Chemical Vapor Deposition

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2507
Author(s):  
Babak Adeli ◽  
Fariborz Taghipour
Keyword(s):  
Solid Solution ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Wide Spectrum ◽  
Direct Synthesis ◽  
Chemical Vapor ◽  
Building Blocks ◽  
Operating Conditions ◽  
Wide Range ◽  
Pressure Chemical

Binary and ternary oxynitride solid alloys were studied extensively in the past decade due to their wide spectrum of applications, as well as their peculiar characteristics when compared to their bulk counterparts. Direct bottom-up synthesis of one-dimensional oxynitrides through solution-based routes cannot be realized because nitridation strategies are limited to high-temperature solid-state ammonolysis. Further, the facile fabrication of oxynitride thin films through vapor phase strategies has remained extremely challenging due to the low vapor pressure of gaseous building blocks at atmospheric pressure. Here, we present a direct and scalable catalytic vapor–liquid–solid epitaxy (VLSE) route for the fabrication of oxynitride solid solution nanowires from their oxide precursors through enhancing the local mass transfer flux of vapor deposition. For the model oxynitride material, we investigated the fabrication of gallium nitride and zinc oxide oxynitride solid solution (GaN:ZnO) thin film. GaN:ZnO nanowires were synthesized directly at atmospheric pressure, unlike the methods reported in the literature, which involved multiple-step processing and/or vacuum operating conditions. Moreover, the dimensions (i.e., diameters and length) of the synthesized nanowires were tailored within a wide range.

scholarly journals Fabrication of Micron Scale Magnetic Nickel Features by Selective Area Organometallic Chemical Vapor Deposition

1997 ◽  
Vol 475 ◽  
Author(s):  
D. Welipitiya ◽  
C. N. Borca ◽  
P. A. Dowben ◽  
I. Gobulukoglu ◽  
Hong Jiang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Magnetic Measurements ◽  
Chemical Vapor ◽  
Gradient Force ◽  
Selective Area ◽  
Wide Range ◽  
Radiation Induced ◽  
Organometallic Chemical Vapor Deposition

AbstractWe demonstrate that it is possible to deposit a wide range of magnetic features, using photoassisted and electron radiation induced selective area organometallic chemical vapor deposition. Large arrays of identical micron to nano scale Ni features were deposited by these methods. Their magnetic properties were studied by alternating gradient force magnetometry as well as magnetic force microscopy. Our morphological and magnetic measurements show that the structures are spatially well defined, and the magnetic properties are related to the structural shapes of the features.

Medium-Range Order in a-Si:H Below and Above the Onset of Microcrystallinity

1999 ◽  
Vol 557 ◽  
Author(s):  
D.L. Williamson
Keyword(s):  
Chemical Vapor Deposition ◽  
Solar Cell ◽  
Substrate Temperature ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Range Order ◽  
Medium Range Order ◽  
Hydrogen Dilution ◽  
Wide Range ◽  
Medium Range

AbstractMedium range order (MRO) and the formation of microcrystallites in a-Si:H prepared by plasma-enhanced chemical vapor deposition (PECVD) and hot-wire chemical vapor deposition (HWCVD) have been probed by systematic x-ray diffraction studies with films as thin as those used in solar cells. Effects of substrate temperature, hydrogen dilution, film thickness, and type of substrate have been examined. High-hydrogen-diluted films of 0.5 μm thickness, using optimized deposition parameters for solar cell efficiency and stability, are found to be partially microcrystalline (μc) if deposited directly on stainless steel (SS) substrates but are fully amorphous provided a thin (20 nm) n-layer of a-Si:H or μc-Si:H is first deposited on the SS. The latter predeposition does not prevent partially microcrystallinity if the films are grown thicker (1.5 to 2.5 μm) and this is consistent with a recently proposed phase diagram of thickness versus hydrogen dilution. Analysis of the first (lowest angle) scattering peak of the a-Si:H phase demonstrates that its width, directly related to MRO, is reduced by heavier hydrogen dilution in PECVD growth or by increased substrate temperature in HWCVD growth. The narrowest width of fully amorphous material correlates with better solar cell stability and this is not likely related to bonded hydrogen content since it is quite different in the optimized PECVD and HWCVD a-Si:H. A wide range of MRO apparently exists in the residual amorphous phase of the mixed a/μc material.

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