Rapid and mass-producible synthesis of high-crystallinity MoSe2 nanosheets by ampoule-loaded chemical vapor deposition

Nanoscale ◽  
2020 ◽  
Vol 12 (13) ◽  
pp. 6991-6999 ◽  
Author(s):  
Na Liu ◽  
Woong Choi ◽  
Hyeongi Kim ◽  
Chulseung Jung ◽  
Jeonghun Kim ◽  
...  
Keyword(s):  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Rapid Growth ◽  
Chemical Vapor ◽  
High Crystallinity

Rapid growth of high-crystalline MoSe2 nanosheets with grain size of up to ∼100 μm and yield of milligrams per hour.

Quantitative Modelling of Nucleation Kinetics in Experiments for Poly-Si Growth on Sio2 by Hot-Wire Chemical Vapor Deposition

2001 ◽  
Vol 664 ◽  
Author(s):  
Maribeth Swiatek ◽  
Jason K. Holt ◽  
Harry A. Atwater
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Nucleation Density ◽  
Hot Wire ◽  
Nucleation Kinetics ◽  
Temperature Dependent ◽  
Cluster Density

ABSTRACTWe apply a rate-equation pair binding model of nucleation kinetics [1] to the nucleation of Si islands grown by hot-wire chemical vapor deposition on SiO2 substrates. Previously, we had demonstrated an increase in grain size of polycrystalline Si films with H2 dilution from 40 nm using 100 mTorr of 1% SiH4 in He to 85 nm with the addition of 20 mTorr H2. [2] This increase in grain size is attributed to atomic H etching of Si monomers rather than stable Si clusters during the early stages of nucleation, decreasing the nucleation density. Atomic force microscopy (AFM) measurements show that the nucleation density increases sublinearly with time at low coverage, implying a fast nucleation rate until a critical density is reached, after which grain growth begins. The nucleation density decreases with increasing H2 dilution (H2:SiH4), which is an effect of the etching mechanism, and with increasing temperature, due to enhanced Si monomer diffusivity on SiO2. From temperature-dependent measurements, we estimate the activation energy for surface diffusion of Si monomers on SiO2 to be 0.47 ± 0.09 eV. Simulations of the temperature-dependent supercritical cluster density lead to an estimated activation energy of 0.42 eV ± 0.01 eV and a surface diffusion coefficient prefactor of 0.1 ± 0.03 cm2/s. H2-dilution-dependent simulations of the supercritical cluster density show an approximately linear relationship between the H2 dilution and the etch rate of clusters.

Chemical Vapor Deposition of Binary Metal Germanides

1990 ◽  
Vol 187 ◽  
Author(s):  
M.J. Hampden-Smith ◽  
J. Garvey ◽  
D. Lei ◽  
J.C. Huffman
Keyword(s):  
Thermal Decomposition ◽  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Transition Metal ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Solution Model ◽  
Binary Metal ◽  
Decomposition Experiments

AbstractA series of transition metal substituted germacyclopent-3-ene compounds containing transition metal-germanium bonds have been prepared with supporting ligands which are designed to be easily removed either thermally or photochemically. In solution, model thermal decomposition experiments show that either the geramanium or the transition metal substituents may be removed, depending on the nature of the metal. Preliminary hot-wall CVD experiments using manganese and cobalt derivatives result in films with small grain size.

Effects of Process Parameters on Graphene Growth Via Low-Pressure Chemical Vapor Deposition

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Byoungdo Lee ◽  
Weishen Chu ◽  
Wei Li
Keyword(s):  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Process Parameters ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
High Growth ◽  
Low Pressure ◽  
Large Set ◽  
Graphene Growth ◽  
Pressure Chemical

Abstract Graphene has attracted enormous research interest due to its extraordinary material properties. Process control to achieve high-quality graphene is indispensable for graphene-based applications. This research investigates the effects of process parameters on graphene quality in a low-pressure chemical vapor deposition (LPCVD) graphene growth process. A fractional factorial design of experiment is conducted to provide understanding on not only the main effect of process parameters, but also the interaction effect among them. Graphene quality including the number of layers and grain size is analyzed. To achieve monolayer graphene with large grain size, a condition with low CH4–H2 ratio, short growth time, high growth pressure, high growth temperature, and slow cooling rate is recommended. This study considers a large set of process parameters with their interaction effects and provides guidelines to optimize graphene growth via LPCVD focusing on the number of graphene layers and the grain size.

On the oxidation resistance of superhard Ti–Si–C–N coatings

2008 ◽  
Vol 23 (9) ◽  
pp. 2420-2428 ◽  
Author(s):  
Yan Guo ◽  
Shengli Ma ◽  
Kewei Xu ◽  
Tom Bell ◽  
Xiaoying Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Chemical Vapor Deposition ◽  
Oxidation Resistance ◽  
Vapor Deposition ◽  
Silicon Content ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Chemical Vapor ◽  
Surface Morphologies ◽  
The Relationship

The oxidation behavior of three types of plasma-enhanced chemical vapor deposition (PECVD) processed Ti–Si–C–N coatings with silicon content ranging from 4.3 to 11.6 at.% has been investigated at high temperatures. Systematic characterization was conducted to study the evolution of composition, phase constituents, hardness, surface morphologies, microstructures, and grain size during oxidation. A two-stage oxidation process was observed between 700 and 1000 °C for all three coatings. Experimental results indicate that a superhardness of 40 GPa can be maintained up to 700, 800, and 850 °C for 4.3, 7.4, and 11.6 at.% Si coatings, respectively; the dual-phased 7.4 and 11.6 at.% Si coatings show a better oxidation resistance than the single-phased 4.3 at.% Si coating. On the basis of the results, a mechanism is proposed to explain the relationship between the nanostructure and oxidation behavior.

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