Formation of recoil atoms and layer-by-layer sputtering of the single crystal surface under ion bombardment at grazing angles (original) (raw)
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Journal of Applied Physics
We compare various sputtering simulation methods to experimental results in both the low energy (<1 keV) and high energy (≥1 keV) impact regimes for argon ions impacting a pure copper substrate at normal incidence. Our results indicate that for high energy impacts, both binary collision approximation (BCA) and molecular dynamics methods can be used to generate reasonable predictions for the yield and energy distribution of the sputtered atoms. We also find reasonable agreement between the theoretical and experimental results down to impact energies of 600 eV. However, at 200 eV impact energies, significant discrepancies appear between the experimental and theoretical ejecta energy distributions in the peak position, the width of the energy distribution, and the magnitude of the high energy tail. These discrepancies appear to arise from the experimental results being only for atoms sputtered normal to the substrate surface, whereas the theoretical results are integrated over all 2π solid angles above the surface. Using the BCA code SDTrimSP and limiting the results to only atoms emitted within ±15°of the surface normal brings theory and experiment into reasonable agreement. These results suggest that for low energy impacts, the energy distribution of sputtered atoms is highly dependent on the emission angle of the ejecta.
Surface channelling in grazing-incidence ion bombardment of a stepped surface
2007
Using molecular-dynamics simulation, the impact of a 5 keV Ar atom at 83°incidence angle towards the surface normal onto a stepped Pt(1 1 1) surface is investigated. The projectile impinges with a ½ 1 1 2 azimuth on a B step. The channelling of trajectories below the upper terrace is characterized in terms of the distribution of channelling lengths and the energy loss of channelled projectiles. The influence of target temperature is studied by simulating targets at 0 K and at 550 K.
Modelling and Simulation in Materials Science and Engineering, 2008
Ar+Ni(100) collision system was investigated by using isoenergic Molecular Dynamics (MD) simulations. We have focused on the sputtering process upon ion impact and surface damage. Our earlier sequential MD simulation program was first converted into a parallel code [1], and then, it was used to study threshold energy region of the sputtering process on the Ni(100). Next, we have used this code with an effective and favorable algorithm to mimic a re al 1 keV ion impact on Ni(100) experiment [2]. The Ni(100) slab is formed by 63700 atoms. In order to preserve the to tal energy in the simulation at this collision energy a small time step (0.1 fs) is used. The total observation time is about 2.25 ps. Results were found to be in good agreement with the experiment [2].
Interaction of MEV atomic ions with molecular solids: Ion track structure and sputtering phenomena
Radiation Measurements, 1997
Recent results obtained in our research groups from studies of the interactions of swift, heavy atomic ions with molecular solids are concisely outlined. The focus is on material ejection (sputtering) and surface track formation. The experimental techniques employed include time-of-flight mass spectrometry, energy analysis, collection and analysis of sputtered material, and scanning force microscopy. Characteristics of the sputtering process probed include the sputtering yield, radial and axial velocity di.stributions, angular distributions, and surface track morphology. Besides reviewing and correlating experimental results, we also emphasize the common quasi-thermal origin of pressure-pulse/hydrodynamic and evaporative spike sputtering models.
Study of Ion Scattering Process by the Method of Binary Collision Approximation
2018
"In this paper presents the computer simulation method based on binary collision approximation for a study of low energy (E 0 = 1-15 keV) ion collisions on the surface of a solid and of the accompanying effect like namely scattering. The peculiarities of the process of correlated small angle scattering of 1-5 keV Ne Ar ions by the Cu(100) single-crystal surfaces have been investigated by computer simulation. It has been shown that under these conditions the inelastic energy losses become predominant over the elastic ones Kutliev Uchkun Otoboevich | Karimov Muxtor Karimberganovich | Narimonov Nurbek Davronbekovich""Study of Ion Scattering Process by the Method of Binary Collision Approximation"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-4 , June 2017, URL: http://www.ijtsrd.com/papers/ijtsrd133.pdf Article URL: http://www.ijtsrd.com/physics/computational-physics/133/study-of-ion-scattering-process-by-the-method-of-binary-collision-approximation/kutliev-uchkun-otoboevich"
Grazing Ion-Surface Collisions
Electron emission after grazing ion-surface collisions is studied for high impact velocities. We have focused on glancing angles of electron emission where the dominant mechanism is the ionization from atomic bound states. To describe this process, we introduce a quantum model called field distorted-wave (FDW) approximation, which takes into account the effect of the surface interaction on the electronic transition.
A general potential for molecular dynamics of ion-sputtered surfaces
arXiv: Chemical Physics, 2015
Erosion of surface atoms of solid materials by ion bombardment (surface-sputtering) causes nano-ripples and quantum dots to self-organise on the surfaces. The self-organisation had been shown, in some sputtering experiments, to be influenced by unexpected contaminants (ions) from vacuum walls. Existing inter-atomic-interaction potentials of Molecular Dynamics (MD) simulations for studying this are unsuitable because they assume two-particle collisions at a time instead of many (including contaminants)-particle collisions (Wider-area Perturbations, (WP)). We designed this study to develop a suitable potential that incorporates WP of the MD. We developed the general potential to account for the possibility of WP due to contaminants (both foreign and local to the material) consequently shifting the eqiulibrium points of the MD the material. For instance, dynamics of Au and Fe were studied with O bombardments/contamination (oxygenated environments), and those of CSiGe were studied with ...
Molecular dynamics simulations of ion irradiation of a surface under an electric field
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014
The presence of high electric fields may affect significantly the process of sputtering of metal surfaces by energetic ions, especially in the vicinity of rough surface features. The effect can be significant if the energy of ions is fairly low. Moreover, the nanosized rough surface features -invisible to a naked eye, both intrinsic ones due to technological processing of surfaces and those forming because of sputtering -may affect the topology of surface erosion under ion bombardment. In this work we study by means of concurrent electrodynamics-molecular dynamics the sputtering yield of Cu þ ions hitting a flat Cu surface or a nanosized Cu protrusion as a function of both ion energy and electric field strength. The results show that the sputtering yield is significantly enhanced in the presence of an electric field in both cases.
Influence of collision cascade statistics on pattern formation of ion-sputtered surfaces
Physical Review B, 2005
Theoretical continuum models that describe the formation of patterns on surfaces of targets undergoing ion-beam sputtering, are based on Sigmund's formula, which describes the spatial distribution of the energy deposited by the ion. For small angles of incidence and amorphous or polycrystalline materials, this description seems to be suitable, and leads to the classic BH morphological theory [R. M. Bradley and J. M. E. Harper, J. Vac. Sci. Technol. A 6, 2390 ]. Here we study the sputtering of Cu crystals by means of numerical simulations under the binary-collision approximation. We observe significant deviations from Sigmund's energy distribution. In particular, the distribution that best fits our simulations has a minimum near the position where the ion penetrates the surface, and the decay of energy deposition with distance to ion trajectory is exponential rather than Gaussian. We provide a modified continuum theory which takes these effects into account and explores the implications of the modified energy distribution for the surface morphology. In marked contrast with BH's theory, the dependence of the sputtering yield with the angle of incidence is non-monotonous, with a maximum for non-grazing incidence angles.