Adatom diffusion on vicinal surfaces with permeable steps

Ranguelov, Bogdan; Markov, Ivan

doi:10.2478/s11534-009-0048-2

Cited by 5 publications

(3 citation statements)

References 31 publications

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“…Lastly, we mention one targeted kinetic Monte Carlo simulation study of a stochastic lattice-gas model which assessed the propensity for step crossing as a function of step attachment barriers and kink separation [25]. Clearly, this crossing propensity is closely related to permeability, and these simulations indicated a qualitative dependence on model parameters consistent with previous studies.…”

Section: Introductionsupporting

confidence: 76%

Permeability and kinetic coefficients for mesoscale BCF surface step dynamics: Discrete two-dimensional deposition-diffusion equation analysis

Zhao

Evans

2016

Phys. Rev. B

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A discrete version of deposition-diffusion equations appropriate for description of step flow on a vicinal surface is analyzed for a two-dimensional grid of adsorption sites representing the stepped surface and explicitly incorporating kinks along the step edges. Model energetics and kinetics appropriately account for binding of adatoms at steps and kinks, distinct terrace and edge diffusion rates, and possibly asymmetric barriers for attachment to steps. Analysis of adatom attachment fluxes as well as limiting values of adatom densities at step edges for non-uniform deposition scenarios allows determination of both permeability and kinetic coefficients. Behavior of these quantities is assessed as a function of key system parameters including kink density, step attachment barriers, and the step edge diffusion rate.

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Section: Introductionsupporting

confidence: 76%

Permeability and kinetic coefficients for mesoscale BCF surface step dynamics: Discrete two-dimensional deposition-diffusion equation analysis

Zhao

Evans

2016

Phys. Rev. B

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“…This mechanism was used also to explain the step-up drift induced SB, for which change of the sign of adatom charge, the nature of the bias, etc., were evoked. The present paradigm was formed with the important input from S. Stoyanovthe destabilization due to a step-up adatom drift is stemming from a specific step propertythe so-called step transparency − (or permeability , )the adatoms, during their diffusion along the surface, almost do not feel the transparent steps as special points on the surface, and this prevents the steps from being sinks/sources of adatoms. This property allows for the adatom fluxes to carry information on the local ordering along the surface over many initial terrace distances across the steps .…”

Section: Introductionmentioning

confidence: 99%

Scaling and Dynamic Stability of Model Vicinal Surfaces

Krzyżewski

Załuska‐Kotur

Krasteva

et al. 2018

Crystal Growth & Design

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We propose an integrated modeling approach to the fundamental problem of vicinal crystal surfaces destabilized by step-down (SD) and step-up (SU) currents with focus on both the initial and the intermediate stages of the process. We reproduce and analyze quantitatively the step bunching (SB) instability, caused by the two opposite drift directions in the two situations of step motion mediating sublimation and growth. For this reason we develop further our atomistic scale model (vicCA) of vicinal crystal growth (Gr) destabilized by SD drift of the adatoms in order to account for also the vicinal crystal sublimation (Sbl) and the SU drift of the adatoms as an alternative mode of destabilization. For each of the four possible casesGr + SD, Gr + SU, Sbl + SD, Sbl + SU, we find a self-similar solutionthe time-scaling of the number of steps in the bunch N, = N T 2 /3, where T is the time, rescaled with a combination of model parameters. In order to study systematically the emergence of the instability, we use N further as a measure and probe the model's stability against SB on a dense grid of points in the parameter space. Stability diagrams are obtained, based on simulations running to fixed moderate rescaled times and with small-size systems. We confirm the value of the numerical prefactor in the time scaling of N, 2/ 3 by results obtained from systems of ordinary differential equations for the step velocity that contain, in contrast to vicCA, step−step repulsions. This last part of our study provides also the possibility to distinguish between diffusion-limited and kinetic-limited versions of the step bunching phenomenon.

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“…[40,58,59] Other authors have theorized that upwards diffusion might be facilitated by step "permeability. [60][61][62][63][64] Normally, step edges are considered stable "sinks" for adatoms due to the formation of lateral bonds. As such, adatoms that have attached are only able to move along the edge, but cannot leave the edge for the terrace, and this would be the case irrespective of whether an adatom approached the edge from the ascending or descending directions.…”

Section: Epitaxymentioning

confidence: 99%

Dynamics of the Early Stages in Metal-on-Insulator Thin Film Deposition

Lü¹

2014

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Thin films consist of nanoscale layers of material that are used in many technological applications to either functionalize a surface or serve as parts in miniaturized devices. The properties of a film are closely related to its microstructure, which in turn can be tuned during film preparation. Thin film growth involves a multitude of atomic-scale processes that cannot always be easily studied experimentally. Therefore, different types of computer simulations have been developed in order to test theoretical models of thin film growth in a highly controlled way. To be able to compare simulation and experimental results, the simulations must be able to model events on experimental time-scales, i.e. several seconds or minutes. This is achievable with the kinetic Monte Carlo method.In this work, kinetic Monte Carlo simulations are used to model the initial growth stages of metal films on insulating, amorphous substrates. This includes the processes of island nucleation, three-dimensional island growth and island coalescence. Both continuous and pulsed vapor fluxes are investigated as deposition sources, and relations between deposition parameters and film morphology are formulated. Specifically, the film thickness at what is known as the "elongation transition" is studied as a function of the temporal profile of the vapor flux, adatom diffusivity and the coalescence rate. Since the elongation transition occurs due to hindrance of coalescence completion, two separate scaling behaviors of the elongation transition film thickness are found: one where coalescence occurs frequently and one where coalescence occurs infrequently. In the latter case, known nucleation behaviors can be used favorably to control the morphology of thin films, as these behaviors are not erased by island coalescence. Experimental results of Ag growth on amorphous SiO 2 that confirm the existence of these two "growth regimes" are also presented for both pulsed and continuous deposition by magnetron sputtering. Knowledge of how to avoid coalescence for different deposition conditions allows nucleation for metal-on-insulator material systems to be studied and relevant physical quantities to be determined in a way not previously possible. This work also aids understanding of the growth evolution of polycrystalline films, which in conjunction with advanced deposition techniques allows thin films to be tailored to specific applications.ii iii PREFACE

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Adatom diffusion on vicinal surfaces with permeable steps

Cited by 5 publications

References 31 publications

Permeability and kinetic coefficients for mesoscale BCF surface step dynamics: Discrete two-dimensional deposition-diffusion equation analysis

Permeability and kinetic coefficients for mesoscale BCF surface step dynamics: Discrete two-dimensional deposition-diffusion equation analysis

Scaling and Dynamic Stability of Model Vicinal Surfaces

Dynamics of the Early Stages in Metal-on-Insulator Thin Film Deposition

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