Surface Pseudorotation in Lewis-Base-Catalyzed Atomic Layer Deposition of SiO2: Static Transition State Search and Born–Oppenheimer Molecular Dynamics Simulation

2012 ◽  
Vol 116 (50) ◽  
pp. 26436-26448 ◽  
Author(s):  
Guoyong Fang ◽  
Shuang Chen ◽  
Aidong Li ◽  
Jing Ma
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Atomic Layer Deposition ◽  
Transition State ◽  
Atomic Layer ◽  
Lewis Base ◽  
Dynamics Simulation ◽  
Layer Deposition ◽  
Transition State Search

scholarly journals Influence of the Geometric Parameters on the Deposition Mode in Spatial Atomic Layer Deposition: A Novel Approach to Area-Selective Deposition

Coatings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 5 ◽  
Author(s):  
César Masse de la Huerta ◽  
Viet Nguyen ◽  
Jean-Marc Dedulle ◽  
Daniel Bellet ◽  
Carmen Jiménez ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Atomic Layer Deposition ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Dynamics Simulation ◽  
Selective Deposition ◽  
Temporal Separation ◽  
Present Contribution ◽  
Chemical Vapor Deposition Growth ◽  
Layer Deposition

Within the materials deposition techniques, Spatial Atomic Layer Deposition (SALD) is gaining momentum since it is a high throughput and low-cost alternative to conventional atomic layer deposition (ALD). SALD relies on a physical separation (rather than temporal separation, as is the case in conventional ALD) of gas-diluted reactants over the surface of the substrate by a region containing an inert gas. Thus, fluid dynamics play a role in SALD since precursor intermixing must be avoided in order to have surface-limited reactions leading to ALD growth, as opposed to chemical vapor deposition growth (CVD). Fluid dynamics in SALD mainly depends on the geometry of the reactor and its components. To quantify and understand the parameters that may influence the deposition of films in SALD, the present contribution describes a Computational Fluid Dynamics simulation that was coupled, using Comsol Multiphysics®, with concentration diffusion and temperature-based surface chemical reactions to evaluate how different parameters influence precursor spatial separation. In particular, we have used the simulation of a close-proximity SALD reactor based on an injector manifold head. We show the effect of certain parameters in our system on the efficiency of the gas separation. Our results show that the injector head-substrate distance (also called deposition gap) needs to be carefully adjusted to prevent precursor intermixing and thus CVD growth. We also demonstrate that hindered flow due to a non-efficient evacuation of the flows through the head leads to precursor intermixing. Finally, we show that precursor intermixing can be used to perform area-selective deposition.

Wettability Transition of a Liquid Droplet on Solid Surface With Nanoscale Inverted Triangular Grooves

2019 ◽  
Author(s):  
Meiling Cai ◽  
Yuxiu Li ◽  
Ying Chen ◽  
Jinliang Xu ◽  
Longyan Zhang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Transition State ◽  
Molecular Interaction ◽  
Liquid Droplet ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Potential Strength ◽  
Solid Liquid ◽  
Wetting Behaviors

Abstract Inspired by a few phenomena in nature such as the lotus leaf, red rose petal, gecko’s feet and Nepenthes Alata plant, much attention has been paid to use simple and feasible means to achieve remarkable wetting behaviour for many applications in various areas including self-cleaning for building exteriors and windshields, oil/water separation, anti-icing, liquid collecting, anti-fogging and anti-corrosion. Based on the established theoretical models, wetting behaviour of a liquid droplet obtained by molecular dynamics simulation method is generally in good agreement with the experimental results. In macro and micro scale, the previous theories can explain and predict the wetting behaviors well. However, these theories are invalid for nanoscale. It is essential to reveal the underlying physical mechanism of the wetting behaviors of the droplet on solid surface with nanoroughness. Extensive studies on nanosale wettability focus on the effect of nano structures on wettability state. Desired wetting behavior of rough material surface achieved by nanosize reentrant geometry like “T” or mushroom shape and other variant geometry with solid overhangs has been widely used in self-cleaning surfaces, heat exchange and many applications. For example, “T” shape groove with different depths and widths under nanoscale has been considered to confer superhydrophobicity to hydrophilic surfaces gradually. In this paper, wettability transition of a liquid droplet on geometrically heterogeneous solid substrate with nanoscale structures of inverted triangular grooves is investigated by using molecular dynamics simulation method under the parameter space spanned by structure geometry and solid-liquid molecular interaction potential strength. Three wettability states, namely Cassie nonwetting state, Cassie-to-Wenzel transition state and Wenzel wetting state, are identified with various geometries and potential strength. For Cassie nonwetting state, increasing height of the triangles has less effect on wettability transition with weak solid-liquid molecular interaction. Besides, the Cassie nonwetting state is less sensitive to different interval between the triangles as solid-liquid molecular interaction is weak. For Cassie-to-Wenzel transition state, increasing height of the triangles and decreasing interval between the triangles decrease wettability. For Wenzel wetting state, increasing interval between the triangles with low height increases wettability. With strong solid-liquid molecular interaction, different interval between the triangles results in wetting state transition from Wenzel to transition state. What’s more, liquid droplet changes its state from Wenzel wetting state to Cassie-to-Wenzel transition state with increasing height of the triangles or decreasing interval between the triangles. Three wettability transition regions are identified in the parameter space.

Influence of Alkalinity and Steric Hindrance of Lewis-Base Catalysts on Atomic Layer Deposition of SiO2

2011 ◽  
Vol 115 (47) ◽  
pp. 23363-23373 ◽  
Author(s):  
Shuang Chen ◽  
Guoyong Fang ◽  
Xu Qian ◽  
Aidong Li ◽  
Jing Ma
Keyword(s):  
Atomic Layer Deposition ◽  
Steric Hindrance ◽  
Atomic Layer ◽  
Lewis Base ◽  
Base Catalysts ◽  
Layer Deposition ◽  
Lewis Base Catalysts

scholarly journals Noble Metal Alloy Thin Films by Atomic Layer Deposition & Rapid Joule Heating

2021 ◽  
Author(s):  
Yuanyuan Guo ◽  
Yiming Zou ◽  
Chunyu Cheng ◽  
Leyan Wang ◽  
Riko I Made ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Atomic Layer Deposition ◽  
Joule Heating ◽  
Atomic Layer ◽  
Metal Alloy ◽  
Dynamics Simulation ◽  
Alloy Films ◽  
X Ray ◽  
Layer Deposition

Abstract Metal alloys are usually fabricated by melting constituent metals together or sintering metal alloy particles made by high energy ball milling (mechanical alloying). All these methods only allow for bulk alloys to be formed. This manuscript details a new method of fabricating Rhodium/Iridium (Rh/Ir) metal alloy films using atomic layer deposition (ALD) and rapid Joule heating induced alloying that gives functional thin film alloys, enabling conformal thin films with high aspect ratios on 3D nanostructured substrate. In this work, ALD was used to deposit Rh thin film on an Al2O3 substrate, followed by an Ir overlayer on top of the Rh film. The multilayered structure was then alloyed / sintered using rapid Joule heating. We can precisely control the thickness of the resultant alloy films down to the atomic scale. The Rh@Ir alloy thin films were characterized using scanning and transmission electron microscopy (SEM/TEM) and energy dispersive spectroscopy (EDS) to study their microstructural characteristics. Grazing-incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS) were also carried out to confirm the composition and formation of Rh-Ir thin film alloys. All the characterization results reveal that the Rh-Ir alloy thin film was prepared successfully with one single phase and homogeneous distribution of Rh and Ir throughout the film. Molecular Dynamics simulation experiments of Rh/Ir alloys using Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) were performed to elucidate the alloying mechanism during the rapid heating process, corroborating the experimental results.

Molecular-Dynamics Simulation of the Initial Period of Cluster Deposition

2002 ◽  
Vol 749 ◽  
Author(s):  
K. Shintani ◽  
T. Nakajima ◽  
Y. Taniguchi
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Initial Period ◽  
Equations Of Motion ◽  
Atomic Layer ◽  
Deposition Process ◽  
Dynamics Simulation ◽  
Soft Landing ◽  
Embedded Atom ◽  
Embedded Atom Method Potential

ABSTRACTThe initial periods of deposition process of metal clusters in the soft-landing regime are investigated by the molecular-dynamics simulation. The embedded-atom method potential is adopted for calculation of the interaction between metallic atoms. The predictor-corrector method for second-order differential equations is employed for integration of the equations of motion. A simulation begins with equilibration of clusters and a substrate at a specified temperature. The lowest atomic layer in the substrate is fixed and the next few atomic layers are set to be velocity-scaling layers during the deposition process. The periodic boundary conditions are imposed in the horizontal directions. A single cluster with no velocity is deposited on the substrate. The simulations are performed at different temperatures of the clusters and substrate and for different sizes of clusters. How the morphological transition of the deposited nanostructures is affected by these parameters is discussed.

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