scholarly journals Influence of The Electrochemical Environment on Diffusion Processes Near Step and Island Edges: Ag(111) and Ag(100)

1999 ◽  
Vol 580 ◽  
Author(s):  
Michael I. Haftel ◽  
T. L. Einstein
Keyword(s):  
Surface Charge ◽  
Diffusion Processes ◽  
Diffusion Barriers ◽  
Step Edge ◽  
Metallic Surfaces ◽  
Embedded Atom ◽  
Powerful Means ◽  
Coarsening Dynamics ◽  
Coarsening Kinetics ◽  
Monotonically Decrease

AbstractThe electrochemical cell provides a potentially powerful means of altering morphology and islanding phenomena on metallic surfaces. Diffusion and attachment processes on terraces and near step and island edges are known to profoundly affect island sizes, shapes and coarsening kinetics. Using the surface-embedded-atom-model (SEAM) for describing metallic surfaces in the electrolytic environment, we calculate the dependence of the activation energies for the aforementioned diffusion processes on the deposited surface charge for the Ag(111) and Ag(100) surfaces in an electrolytic environment. While all these processes show some degree of dependence on the potential, the step-edge barrier and the edge diffusion processes are the most sensitive. Step-edge barriers increase (to over 1 eV) with large positive potential (0.85 V), while edge diffusion barriers monotonically decrease with positive surface charge on Ag(100) and Ag(111). We assess the effect these diffusion barriers have on island size/shapes and coarsening dynamics and discuss the implications on electrochemical tuning of islanding phenomena.

The Ehrlich-Schwoebel Effect for Vacancies: Low-Index Faces of Silver

2000 ◽  
Vol 648 ◽  
Author(s):  
Michael I. Haftel
Keyword(s):  
Diffusion Barrier ◽  
Activation Barrier ◽  
Diffusion Barriers ◽  
Step Edge ◽  
Embedded Atom Method ◽  
Vacancy Diffusion ◽  
Exchange Diffusion ◽  
Embedded Atom ◽  
And Diffusion ◽  
Step Edges

AbstractWe employ surface-embedded-atom-method potentials to investigate the diffusion barriers of vacancies diffusing over and near steps on the low index faces of silver. Barriers for vacancy terrace diffusion, diffusion over step-edges, and diffusion along step edges, including around corners, are calculated. Vacancies are significantly less mobile than adatoms and have large Ehrlich-Schwoebel (ES) barriers on all three faces. For Ag(100) the diffusion barrier for vacancies along step-edges is virtually the same (474 meV) as on the terrace. As in diffusion near the step edge, vacancies encounter a significant increase (213 meV) in the activation barrier when diffusing around the corner of a vacancy island (the corner analogue of the ES barrier), but the excess barrier around a kink all but disappears because exchange diffusion is favorable there. The consequences of the vacancy diffusion barriers on 3D pitting and on island diffusion and coarsening are discussed.

DIFFUSION MECHANISMS AT fcc METAL SURFACES — EMBEDDED ATOM METHOD CALCULATIONS

1995 ◽  
Vol 09 (01) ◽  
pp. 1-44 ◽  
Author(s):  
CHUN-LI LIU
Keyword(s):  
Metal Surfaces ◽  
Diffusion Processes ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Simulation Techniques ◽  
Theoretical Investigations ◽  
Diffusion Mechanisms ◽  
Fcc Metal ◽  
Dynamic Diffusion ◽  
Computer Simulation Techniques

Recent development in theoretical investigations using computer simulation techniques and the embedded atom method (EAM) on diffusion processes critical to nucleation and growth of thin films at fcc metal surfaces is reviewed. Through these investigations, interactions between adatoms and substrate, adatoms and steps, and clusters and substrate and the effect of these interactions on dynamic diffusion processes are further understood. The results from these theoretical investigations are generally consistent with available experimental data and have provided explanations for some experimental observations. Some predictions made a few years ago from these studies have been confirmed by the latest experiments.

Flat-surface, step-edge, facet–facet, and facet–step diffusion barriers in growth of a Pb mesa

2008 ◽  
Vol 602 (13) ◽  
pp. 2284-2294 ◽  
Author(s):  
Yong Han ◽  
Guang-Hong Lu ◽  
Byeong-Joo Lee ◽  
Feng Liu
Keyword(s):  
Flat Surface ◽  
Diffusion Barriers ◽  
Step Edge ◽  
Surface Step

Study of the Reactive Dynamics of Nanometric Metallic Multilayers Using Molecular Dynamics : The Al-Ni System

2012 ◽  
Vol 323-325 ◽  
pp. 89-94
Author(s):  
A. Linde ◽  
Olivier Politano ◽  
F. Baras
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
Solid State Reaction ◽  
Diffusion Processes ◽  
Layer By Layer ◽  
Fixed Temperature ◽  
Embedded Atom ◽  
Specific Geometry ◽  
Reactive Dynamics ◽  
Embedded Atom Method Potential

A molecular dynamics study of a layered Ni-Al-Ni system is developed using an embedded atom method potential. The specific geometry is designed to model a Ni-Al nanometric metallic multilayer. The system is initially thermalized at the fixed temperature of 600 K. We first observe the interdiffusion of Ni and Al at the interfaces, which is followed by the spontaneous phase formation of B2-NiAl in the Al layer. The solid-state reaction is associated with a rapid system's heating which further enhances the diffusion processes. NiAl phase is organized in small regions separated by grain boundaries. This study confirms the hypothesis of a layer-by-layer development of the new phase. For longer times, the temperature is notably higher (> 1000 K) and the system may partly lose some its B2-NiAl microstructure in favor of the formation of Ni3Al in L12 configuration. This work shows the spontaneous development of a real exothermic solid-state reaction in metallic nanosystems mostly constituted by interfaces.

DIFFUSION MECHANISMS DURING EPITAXY OF Cu/Cu(100) — AN ATOMIC VIEW

1994 ◽  
Vol 08 (13) ◽  
pp. 823-832 ◽  
Author(s):  
CHUN-LI LIU
Keyword(s):  
Diffusion Processes ◽  
Diffusion Mechanism ◽  
Atomic Diffusion ◽  
Stable Phase ◽  
Dissociation Energies ◽  
Embedded Atom ◽  
Higher Temperature ◽  
Simulation Results ◽  
Small Clusters ◽  
Eam Potential

Using an embedded atom method (EAM) potential, we have investigated the energetics of atomic diffusion processes of (1) single adatoms on a flat terrace and around steps of different orientations, and (2) small clusters of up to 5 atoms on a flat terrace during epitaxy of Cu/Cu(100). Exchange mechanism for adatoms to cross over descending steps and diffusion mechanism for adatoms to diffuse along step ledges were found to depend on step orientation. The simulation results show that the small clusters are quite mobile at room temperature, but dissociate at much higher temperature, as deduced from the low migration energies and high dissociation energies of the clusters calculated. Under certain conditions, tetramers are only the stable phase during epitaxy of Cu/Cu(100). The simulation results for single adatoms and small clusters obtained in this work are consistent with recent LEED experiments and can explain some experimental observations during epitaxy of Cu/Cu(100).

Surface Photovoltage Monitoring of Silicon Surface Native and Chemical Oxides following Wafer Cleaning and Rinsing Operations

1995 ◽  
Vol 386 ◽  
Author(s):  
John J. Rosato ◽  
R. Mark Hall ◽  
Thad B. Parry ◽  
Paul G. Lindquist ◽  
Taura D. Jarvis
Keyword(s):  
Surface Charge ◽  
Surface Passivation ◽  
Diffusion Processes ◽  
Indirect Measurement ◽  
Surface Photovoltage ◽  
Contamination Level ◽  
Chemical Cleaning ◽  
Wafer Cleaning ◽  
And Diffusion

ABSTRACTWe report on the use of the Surface PhotoVoltage (SPV) technique to monitor the Si surface bonding arrangement, and the impurity metallic contamination level prior to critical diffusion processes via the indirect measurement of surface charge and diffusion length, respectively. We show that the effectiveness of the pre-diffusion wet chemical cleaning and rinsing sequences can be accurately monitored via the real-time, nondestructive SPV measurement. In particular the nature of the surface passivation/chemical oxide formed during the cleaning and rinsing operations can be monitored by quantitative surface charge measurements. The importance of the prior wafer history is highlighted, as is the role of the Si starting material and measurement parameters.

Diffusion Processes and Pre-Exponential Factors in Homo-Epitaxial Growth on Ag(100)

1997 ◽  
Vol 492 ◽  
Author(s):  
Ulrike Kürpick ◽  
Talat S. Rahman
Keyword(s):  
Crystal Growth ◽  
Diffusion Coefficients ◽  
Diffusion Processes ◽  
Step Edge ◽  
Many Body ◽  
Self Diffusion ◽  
Adatom Diffusion ◽  
Exchange Processes ◽  
Exponential Factors ◽  
Vibrational Density

ABSTRACTWe provide a recipe for the evaluation of pre–factors for various diffusion processes relevant to crystal growth on Ag(100), based on explicit calculations of appropriate vibrational density of states using realistic many-body interaction potentials. Our calculated diffusion coefficients show that while hopping processes are favored for terrace self-diffusion, exchange processes dominate step-edge diffusion. We also find the characteristics of adatom diffusion along the < 100 >-step-edge to be strikingly different from the < 110 >-step-edge with interesting consequences for interlayer transport on this surface.

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