Ion damage overrides structural disorder in silicon surface nanopatterning by low-energy ion beam sputtering

Moreno-Barrado, A.; Gago, R.; Redondo-Cubero, A.; Vázquez, Luís; Muñoz-García, Javier; Cuerno, Rodolfo; Lorenz, K.; Castro, Mario

doi:10.1209/0295-5075/109/48003

Cited by 13 publications

(11 citation statements)

References 39 publications

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“…For our experimental system, for which the topmost surface layer can be thought of as an amorphous Si phase with Au impurities, CV terms can be thought of as proxies of surfaceconfined viscous flow, recently shown to describe IBS patterning of clean Si targets. [32][33][34][35][36][37][38][39][40] In such a case, the coefficient in front of the third order derivative term in J B should more properly be related with radiation-induced viscosity. Nevertheless, this fact does not play a relevant role in the discussion to follow.…”

Section: Comparison With Continuum Modelsmentioning

confidence: 99%

“…Seeking for further theoretical descriptions, recall that, for pure Si targets, ripple formation has been recently accounted for on the basis of viscous flow of the topmost amorphized layer. 32,[34][35][36][37][38][39][40] In this approach, a crucial effect of ion irradiation is inducing residual stress in the amorphous layer, which is relaxed via solid flow. The characteristics of the surface dynamics are contingent upon the properties of the non-homogeneous stress distribution that builds up within the layer, 38,39 which in particular controls the value of the critical incidence θ c angle for the ions, above which perpendicular ripples form.…”

Section: Comparison With Continuum Modelsmentioning

confidence: 99%

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Ion-beam nanopatterning of silicon surfaces under codeposition of non-silicide-forming impurities

et al. 2016

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We report experiments on surface nanopatterning of Si targets which are irradiated with 2 keV Ar + ions impinging at near-glancing incidence, under concurrent co-deposition of Au impurities simultaneously extracted from a gold target by the same ion beam. Previous recent experiments by a number of groups suggest that silicide formation is a prerequisite for pattern formation in the presence of metallic impurities. In spite of the fact that Au is known not to form stable compounds with the Si atoms, ripples nonetheless emerge in our experiments with nanometric wavelengths and small amplitudes, and with an orientation that changes with distance to the Au source. We provide results of sample analysis through Auger electron and energy-dispersive X-ray spectroscopies for their space-resolved chemical composition, and through atomic force, scanning transmission electron, and high-resolution transmission microscopies for their morphological properties. We discuss these findings in the light of current continuum models for this class of systems. The composition of and the dynamics within the near-surface amorphized layer that ensues is expected to play a relevant role to account for the unexpected formation of these surface structures.

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Section: Comparison With Continuum Modelsmentioning

confidence: 99%

Section: Comparison With Continuum Modelsmentioning

confidence: 99%

Ion-beam nanopatterning of silicon surfaces under codeposition of non-silicide-forming impurities

et al. 2016

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“…ion range, 38 and which controls the pattern formation process, irrespective of the initial condition (whether crystalline or amorphous) of the target. 32,39 Hence, we do not expect that the target crystallinity influences significantly the pattern order properties observed in Secs. III B-III D.…”

Section: Discussionmentioning

confidence: 87%

Order improvement of surface nanopatterns via substrate rocking under ion bombardment: Experiments and nonlinear models

Jun

Lee

et al. 2020

Phys. Rev. B

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Surface nanopatterns formed by ion beam sputtering (IBS) frequently include a high density of structural defects, which seriously limit their practical applications. Recent theoretical work [M. P. Harrison and R. M. Bradley, Phys. Rev. E 93, 040802(R) ( 2016)], based on the anisotropic Kuramoto-Sivashinsky (aKS) equation, proposes that rocking a substrate during IBS can produce defect-free patterns under certain requirements. We find experimentally, via low-energy Kr + irradiation of Si and amorphous carbon targets, that rocking the substrates generally improves the order of the ripple patterns. Indeed, order is improved even when conditions required in the aKS model are not satisfied. Through numerical simulations, we show that a suitable modification of this equation, in which conserved nonlinear effects are incorporated, reproduces satisfactorily the pattern order in our experimental conditions.

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“…In particular, experimental estimates for noble-gas irradiation of Si conclude [32,42] that the viscosity μ of this layer is very high, close to 1 GPa min, while assuming viscoelasticlike constitutive laws between strain and stress, which are more complex than that for a simple Newtonian fluid, does not improve predictive power in our experimental context [32,43]. Thus the effect of the irradiation can be expressed as residual stress (forcing) that is relaxed via Newtonian viscous flow (relaxation) [44][45][46] and which, as experimentally assessed [47], does not depend on the initial structural state (e.g., crystalline or amorphous) of the target. Results from molecular dynamics (MD) simulations indicate [24] that the corresponding stress tensor is traceless, so that the irradiated layer is incompressible.…”

Section: Theoretical Descriptionmentioning

confidence: 80%

“…Here, p(r, t ) is hydrostatic pressure, μ is viscosity, and I is the identity tensor. MD results additionally indicate [24,41,47] that the residual stress is nonhomogeneously distributed in the irradiated layer and that its value T ext , for a target bombarded under an oblique incidence angle θ is well approximated by a θ rotation of the stress distribution generated under normal incidence [24]. Still, very little additional information is available on the detailed space variation of T ext .…”

Section: Theoretical Descriptionmentioning

confidence: 98%

Stress-driven nonlinear dynamics of ion-induced surface nanopatterns

2019

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For many solid targets, like semiconductors, that become amorphous under irradiation by energetic ions, the outermost surface layer displays formation of asymmetric nanoscale ripples in macroscopic timescales. In contrast to the well-known macroscopic case of an incompressible thin fluid film spreading down an incline, in which the morphological instability is controlled by gravity, here we prove that residual stress induced by the ions is responsible for pattern formation and accounts for its long-time dynamics, even in absence of sputtering effects. Using a continuum framework, we derive closed nonlinear evolution equations for the depth of the irradiated layer. This description includes novel terms associated with the spatial distribution of damage that builds up through sustained bombardment, thus extending to the nanoscale classic models of macroscopic fluidflow systems, and providing detailed information on the pressure and velocity fields within the irradiated layer. Numerical simulations reproduce the main dynamical features of surface nanopatterning under the assumed conditions, elucidating the ensuing nonlinear properties on ripple amplification and transport.

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Ion damage overrides structural disorder in silicon surface nanopatterning by low-energy ion beam sputtering

Abstract: (2015). "Ion damage overrides structural disorder in silicon surface nanopatterning by lowenergy ion beam sputtering" in EPL 109 (2015)

Cited by 13 publications

References 39 publications

Ion-beam nanopatterning of silicon surfaces under codeposition of non-silicide-forming impurities

Ion-beam nanopatterning of silicon surfaces under codeposition of non-silicide-forming impurities

Order improvement of surface nanopatterns via substrate rocking under ion bombardment: Experiments and nonlinear models

Stress-driven nonlinear dynamics of ion-induced surface nanopatterns

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