3,755 research outputs found
Kinetic modelling of epitaxial film growth with up- and downward step barriers
The formation of three-dimensional structures during the epitaxial growth of
films is associated to the reflection of diffusing particles in descending
terraces due to the presence of the so-called Ehrlich-Schwoebel (ES) barrier.
We generalize this concept in a solid-on-solid growth model, in which a barrier
dependent on the particle coordination (number of lateral bonds) exists
whenever the particle performs an interlayer diffusion. The rules do not
distinguish explicitly if the particle is executing a descending or an
ascending interlayer diffusion. We show that the usual model, with a step
barrier in descending steps, produces spurious, columnar, and highly unstable
morphologies if the growth temperature is varied in a usual range of mound
formation experiments. Our model generates well-behaved mounded morphologies
for the same ES barriers that produce anomalous morphologies in the standard
model. Moreover, mounds are also obtained when the step barrier has an equal
value for all particles independently if they are free or bonded. Kinetic
roughening is observed at long times, when the surface roughness w and the
characteristic length scale as and where
and , independently of the growth
temperature.Comment: 15 pages, 7 figure
Modelling of epitaxial film growth with a Ehrlich-Schwoebel barrier dependent on the step height
The formation of mounded surfaces in epitaxial growth is attributed to the
presence of barriers against interlayer diffusion in the terrace edges, known
as Ehrlich-Schwoebel (ES) barriers. We investigate a model for epitaxial growth
using a ES barrier explicitly dependent on the step height. Our model has an
intrinsic topological step barrier even in the absence of an explicit ES
barrier. We show that mounded morphologies can be obtained even for a small
barrier while a self-affine growth, consistent with the Villain-Lai-Das Sarma
equation, is observed in absence of an explicit step barrier. The mounded
surfaces are described by a super-roughness dynamical scaling characterized by
locally smooth (faceted) surfaces and a global roughness exponent .
The thin film limit is featured by surfaces with self-assembled
three-dimensional structures having an aspect ratio (height/width) that may
increase or decrease with temperature depending on the strength of step
barrier.Comment: To appear in J. Phys. Cond. Matter; 3 movies as supplementary
materia
Bioatividade de extratos de sisal (Agave Sisalana Perrine ex Engelm) sobre a oviposição de Ceratitis Capitata (Wiedemann, 1824) (DĂpTERA: Tephritidae).
O Brasil Ă© terceiro maior produtor de frutas do mundo, perdendo apenas para a China e Ăndia, produz frutas tropicais, subtropicais e temperadas. Um dos maiores problemas encontrados pela fruticultura internacional, sĂŁo espĂ©cies de praga s pertencentes Ă famĂlia dos tefritĂdeos
A Geometric Approach to Massive p-form Duality
Massive theories of abelian p-forms are quantized in a generalized
path-representation that leads to a description of the phase space in terms of
a pair of dual non-local operators analogous to the Wilson Loop and the 't
Hooft disorder operators. Special atention is devoted to the study of the
duality between the Topologically Massive and the Self-Dual models in 2+1
dimensions. It is shown that these models share a geometric representation in
which just one non local operator suffices to describe the observables.Comment: 26 pages, LaTeX. The discussion about the equivalence between the
Proca model and two seldual models, with opposite spins, was eliminated.
Typos correcte
Sistema de produção de leite em pastagem de Capim -TanzĂąnia: açÔes de transferĂȘncia de tecnologia.
bitstream/CPAMN/20173/1/CT185.pd
Jerimu 8, batata doce rica em carotenos: estabilidade no cozimento doméstico e no processamento de farinhas.
bitstream/item/118242/1/estabilidade-no-conzimento-domestico-e-processamento-de-farinhas.pd
Avaliacao da adaptabilidade de acessos de Stylosanthes.
Este trabalhao tem como objetivo a apresentacao dos dados referentes a etapa inicial de avaliacao dos materiais, colocados sob teste em 1999.bitstream/item/97614/1/PAND880001.pd
Desempenho reprodutivo de vacas Nelore mantidas em pastagem nativa com suplementação na seca.
bitstream/item/131669/1/Comunicado-162-Desempenho-Reprodutivo-de-Vacas-Nelore.pd
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