Abstract:We use a combination of quenched molecular dynamics and embedded atom method to calculate the activation energy barriers for the hopping and exchange mechanisms of Au, Ag or Cu on Au(100), Ag(100) or Cu(100) stepped surfaces. Our findings show that the Ehrlich–Schwöbel (ES) barriers for an adatom to undergo jump or exchange at a step edge are found to be dependent of the nature of substrate stepped surfaces. We also find that the ES barriers for the hopping processes are too high, except for Cu/Au(100). While … Show more
“…This behavior stems from the presence of a sizeable ES barrier at the step edge which hinders adatom diffusion across the steps 11 . In fact, the ES barrier corresponds to an additional energy needed for an adatom to jump across the terraces 23 , which characterize the (111)A vicinal surface, and decreases the diffusivity in the direction. Therefore, Ga adatoms at T > 400 °C predominantly migrate in the direction along steps in a strongly anisotropic way, this way approaching a quasi-one-dimensional diffusion behavior.Figure 6( a ) AFM image of QDs grown on GaAs(111)A with 2° miscut towards at 300 °C (2 × 2 μm 2 , sample T1), corresponding ( c ) spatial dispersion of neighboring QDs (0.16 × 0.16 μm 2 ) and ( e ) CZD obtained from voronoi tessellation, fitted by GWD.…”
A temperature activated crossover between two nucleation regimes is observed in the behavior of Ga droplet nucleation on vicinal GaAs(111)A substrates with a miscut of 2° towards $$(\bar{1}\bar{1}2)$$
(
1
¯
1
¯
2
)
. At low temperature (<400 °C) the droplet density dependence on temperature and flux is compatible with droplet nucleation by two-dimensional diffusion. Increasing the temperature, a different regime is observed, whose scaling behavior is compatible with a reduction of the dimensionality of the nucleation regime from two to one dimension. We attribute such behavior to a presence of finite width terraces and a sizeable Ehrlich-Schwöbel barrier at the terrace edge, which hinders adatom diffusion in the direction perpendicular to the steps.
“…This behavior stems from the presence of a sizeable ES barrier at the step edge which hinders adatom diffusion across the steps 11 . In fact, the ES barrier corresponds to an additional energy needed for an adatom to jump across the terraces 23 , which characterize the (111)A vicinal surface, and decreases the diffusivity in the direction. Therefore, Ga adatoms at T > 400 °C predominantly migrate in the direction along steps in a strongly anisotropic way, this way approaching a quasi-one-dimensional diffusion behavior.Figure 6( a ) AFM image of QDs grown on GaAs(111)A with 2° miscut towards at 300 °C (2 × 2 μm 2 , sample T1), corresponding ( c ) spatial dispersion of neighboring QDs (0.16 × 0.16 μm 2 ) and ( e ) CZD obtained from voronoi tessellation, fitted by GWD.…”
A temperature activated crossover between two nucleation regimes is observed in the behavior of Ga droplet nucleation on vicinal GaAs(111)A substrates with a miscut of 2° towards $$(\bar{1}\bar{1}2)$$
(
1
¯
1
¯
2
)
. At low temperature (<400 °C) the droplet density dependence on temperature and flux is compatible with droplet nucleation by two-dimensional diffusion. Increasing the temperature, a different regime is observed, whose scaling behavior is compatible with a reduction of the dimensionality of the nucleation regime from two to one dimension. We attribute such behavior to a presence of finite width terraces and a sizeable Ehrlich-Schwöbel barrier at the terrace edge, which hinders adatom diffusion in the direction perpendicular to the steps.
“…[ 38 ] In addition, EAM model is very accurate for highly symmetrical structures (such as fcc). [ 38,39 ] Daw and Baskes [ 37,40 ] developed this method for calculating the potential energy of each atom i as a sum of a pair contribution and an embedding term as given by the following equation:where is the pair potential and is the distance between atom i and atom j ; is the embedding energy function required to place atom i in an electron density characterizing the environment of that atom,where is the sum of the electron densities of all the other atoms j at the location of atom i . This potential is expressed essentially as a function of the separation distance of the atoms in the form of different functions.…”
Section: Simulation Methods and Modelmentioning
confidence: 99%
“…[38] In addition, EAM model is very accurate for highly symmetrical structures (such as fcc). [38,39] Daw and Baskes [37,40] developed this method for calculating the potential energy of each atom i as a sum of a pair contribution and an embedding term as given by the following equation:…”
Herein, a kinetic Monte Carlo (KMC) simulation of the 3D electrodeposition of Ag metal on Ag cathode surface is carried out under galvanostatic, different substrate temperatures, and current density conditions. Both deposition and diffusion processes are considered during the film electrodeposition, where each adatom diffuses via nearest‐neighbor hopping, exchange, and step‐edge atom exchange mechanisms. The interatomic interaction is described within the well‐known embedded atomic method (EAM) framework. The number of hopping, exchange, and step‐edge exchange mechanisms is evaluated using a power law of time
n
hop
∝
t
α
,
n
exch
∝
t
β
, and
n
step
∝
t
γ
, respectively. However, the step‐edge exchange mechanism depends on current density. The effects of deposited atom number, current density, and substrate temperature on the transitions of surface morphologies of the electrodeposited thin film are studied considering different combinations of the mechanisms. The results indicate that surface roughness increases when the number of deposited atoms and the current density increase, but when the substrate temperature increases the roughness decreases. In addition, the resulting surface has been found to be smooth if all diffusion mechanisms are involved in the electrodeposition phenomenon, while roughness occurs when diffusion takes place only via hopping mechanism. Furthermore, the surface roughness behavior is found to be related to clusters and islands distribution.
“…7a with the triangular dots. In this latter simulation, the recombination mechanism was artificially suppressed with the help of forbidding atom transfer from the middle to the lowerst terrace through the lower combinatory step by setting an infinitely high Schwöbel barrier [34].…”
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
