Theoretical aspects of atomic mixing by ion beams
TL;DR: In this paper, the half-widths of matrix relocation profiles were determined explicitly for ion-impurity knockon events (recoil implantation) as well as isotropic cascade mixing.
About: This article is published in Nuclear Instruments and Methods.The article was published on 1981-04-15. It has received 443 citations till now. The article focuses on the topics: Mixing (physics).
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01 Mar 1984-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, a Monte Carlo code was developed to compute range profiles of implanted ions, composition profiles of the target, and sputtering rates for a dynamically varying target composition, taking into account compositional changes both due to the spatial distribution of target atoms deposited in collision cascades, and due to presence of the implanted ions.
Abstract: Based on the sputtering version of the TRIM program for multicomponent targets, a Monte Carlo code has been developed which computes range profiles of implanted ions, composition profiles of the target and sputtering rates for a dynamically varying target composition. It takes into account compositional changes both due to the spatial distribution of target atoms deposited in collision cascades, and due to the presence of the implanted ions. The local density of the target is allowed to relax according to a given function of the densities of the individual components. The applications of the program cover a wide range of problems like the collisional atomic mixing of multilayered targets, dynamic implantation profiles at large fluences, and the fluence-dependent preferential sputtering of multicomponent materials. The present paper provides a description of the program and a critical comparison to similar Monte Carlo codes. As an application, the behaviour of the Ta-C system under He bombardment is studied with respect to sputtering yields, surface composition and composition profiles. Satisfactory agreement is obtained with experimental results given in the literature.
565 citations
TL;DR: In this paper, the authors review the present understanding of defect-interface interactions in single-phase and two-phase metal and oxide nanocomposites, emphasizing how interface structure affects interactions with point, line, and planar defects.
427 citations
Cites background from "Theoretical aspects of atomic mixin..."
...described relocation of impurities based on BM, finding that it is strongly dependent on the mass ratio of the mixed species [386]....
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01 Mar 1985-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the problem of ion-induced mixing of metal bilayers is examined in the limit of heavy metals (Z ≳ 20) and heavy energetic ions (E ≳ 100 keV) and in the absence of delayed effects such as radiation enhanced thermal diffusion.
Abstract: The problem of ion-induced mixing of metal bilayers is examined in the limit of heavy metals (Z ≳ 20) and heavy energetic ions (E ≳ 100 keV) and in the absence of delayed effects such as radiation enhanced thermal diffusion. Thermochemical effects are shown to play an important role in biasing the random walk process of mixing. A universal mixing equation is derived which predicts the evolution of the concentration profile as a function of ion dose. Finally, a model is presented which allows one to predict what metallurgical phases are formed during the mixing process. Criteria for amorphous phase formation are particularly emphasized.
391 citations
TL;DR: In this article, the authors consider the extensive experimental and computer simulation studies that have been performed over the past several decades on what the nature of the primary damage is, and provide alternatives to the current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model for metals.
334 citations
TL;DR: In this article, the authors describe the fundamental mechanisms of producing atomic rearrangements and point defects in cascades, the configurations of defects in their primary state of damage, and the fates of these defects as they migrate away from their nascent locations.
Abstract: This chapter discusses displacement processes in energetic cascades. It describes the fundamental mechanisms of producing atomic rearrangements and point defects in cascades, the configurations of defects in their primary state of damage, and the fates of these defects as they migrate away from their nascent locations. When energetic particles penetrate solids, they lose their energy through a series of elastic two-body nuclear collisions with target atoms and through excitation of the electronic system. It is the elastic collisions that are of primary interest for damage creation in metals and most semiconductors because they lead to the production of Frenkel pairs, which are vacancies and self-interstitial atoms, and to rearrangements of atoms on their lattice sites. The atomic displacement process begins with the creation of a primary knock on atom (PKA), which is any target atom struck by the irradiation particle. Displacements in energetic cascades are a part of a complex dynamics that involves both energetic recoils, which are characterized by binary collisions, and intense local heating.
320 citations
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46,339 citations
TL;DR: In this article, an integrodifferential equation for the sputtering yield is developed from the general Boltzmann transport equation, and solutions of the integral equation are given that are asymptotically exact in the limit of high ion energy as compared to atomic binding energies.
Abstract: Sputtering of a target by energetic ions or recoil atoms is assumed to result from cascades of atomic collisions. The sputtering yield is calculated under the assumption of random slowing down in an infinite medium. An integrodifferential equation for the yield is developed from the general Boltzmann transport equation. Input quantities are the cross sections for ion-target and target-target collisions, and atomic binding energies. Solutions of the integral equation are given that are asymptotically exact in the limit of high ion energy as compared to atomic binding energies. Two main stages of the collision cascade have to be distinguished: first, the slowing down of the primary ion and all recoiling atoms that have comparable energies---these particles determine the spatial extent of the cascade; second, the creation and slowing down of low-energy recoils that constitute the major part of all atoms set in motion. The separation between the two stages is essentially complete in the limit of high ion energy, as far as the calculation of the sputtering yield is concerned. High-energy collisions are characterized by Thomas-Fermi-type cross sections, while a Born-Mayer-type cross section is applied in the low-energy region. Electronic stopping is included when necessary. The separation of the cascade into two distinct stages has the consequence that two characteristic depths are important for the qualitative understanding of the sputtering process. First, the scattering events that eventually lead to sputtering take place within a certain layer near the surface, the thickness of which depends on ion mass and energy and on ion-target geometry. In the elastic collision region, this thickness is a sizable fraction of the ion range. Second, the majority of sputtered particles originate from a very thin surface layer (\ensuremath{\sim}5 \AA{}), because small energies dominate. The general sputtering-yield formula is applied to specific situations that are of interest for comparison with experiment. These include backsputtering of thick targets by ion beams at perpendicular and oblique incidence and ion energies above \ensuremath{\sim}100 eV, transmission sputtering of thin foils, sputtering by recoil atoms from $\ensuremath{\alpha}$-active atoms distributed homogeneously or inhomogeneously in a thick target, sputtering of fissionable specimens by fission fragments, and sputtering of specimens that are irradiated in the core of a reactor or bombarded with a neutron beam. There is good agreement with experimental results on polycrystalline targets within the estimated accuracy of the data and the input parameters entering the theory. There is no need for adjustable parameters in the usual sense, but specific experimental setups are discussed that allow independent checks or accurate determination of some input quantities.
2,552 citations
TL;DR: In this article, it is shown that the bulk radiation damage accompanying sputtering events sets ultimate limits to the depth resolution attainable in sputter profiling, and guidelines for selection of projectile species and energies to minimize such mixing are given and numerical estimates for attainable depth resolutions.
Abstract: It is shown that the bulk radiation damage accompanying sputtering events sets ultimate limits to the depth resolution attainable in sputter profiling. These limits have been reached in a few cases but most published experimental resolutions are dominated either by instrumental effects or deterioration of depth resolution caused by surface-topography changes. The radiation-damage induced mixing is called “cascade mixing”. Guidelines for selection of projectile species and energies to minimize such mixing are given and numerical estimates for attainable depth resolutions are presented. Finally, the influence of cascade mixing is assessed relative to that of recoil implantation.
519 citations