Erosion of Ag surface by continuous irradiation with slow, large Ar clusters

Surface & Interface Analysis

Garrison

et al. 2012

Self Cite

Molecular dynamics computer simulations are employed to investigate the role of the substrate cohesive energy on the impact angle dependence of the sputtering yield for Ar 60 and Ar 2953 projectiles bombarding a benzene molecular solid and a Ag(111) atomistic sample. A different dependence of the total sputtering yield on the impact angle is observed for small and large projectiles for benzene, while a similar dependence is observed for Ag (111). It is demonstrated that the increase of the cohesive energy leads to a significant decrease of the total ejection signal for both Ar 60 and Ar 2953 projectiles. The shape of the impact angle dependence, however, is much less sensitive to this parameter. The 'washing out' mechanism and the structural differences of the irradiated samples are proposed to be responsible for the different shapes of the impact angle dependence.

Section: Introductionsupporting

confidence: 83%

Sputtering of a coarse‐grained benzene and Ag(111) crystals by large Ar clusters – effect of impact angle and cohesive energy

Rzeznik

Surface & Interface Analysis

Garrison

et al. 2012

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“…A similar behavior has been observed for fullerene impacts on a coarse-grained benzene solid [11] and in the studies of large Ar cluster bombardment of metal targets. [18,19] In the last case, the shape does not change even for large Ar clusters. For Ar 2953 cluster bombardment of benzene the yield strongly increases with the impact angle and has a maximum around 45 o followed by a steep decrease at larger angles.…”

Section: Resultsmentioning

confidence: 91%

Dynamics of large Ar cluster bombardment of organic solids

Postawa

Surface & Interface Analysis

Rzeznik

et al. 2012

Molecular dynamics computer simulations are used to investigate the ejection process of molecules from a benzene crystal bombarded with keV large Ar clusters. The effect of projectile size, the kinetic energy and the impact angle on the sputtering efficiency is investigated. The results show that although the sputtering yield depends on all projectile parameters, this dependence can be greatly simplified if the sputtering yield per projectile nucleon is expressed as a function of projectile kinetic energy per nucleon. A different dependence of the total sputtering yield on the impact angle has been observed for small and large projectiles. This effect is attributed to a 'washing out' mechanism. For large projectiles most of the organic molecules are ejected by gentle collective action of argon atoms. Proper selection of the projectile parameters allows for achieving conditions where only intact molecules are emitted.

“…The setup of the MD simulations was described in greater detail previously. 12,20,21 Rectangular boxes of Ag(111) samples, measuring approximately from 26 Â 26 Â 13 to 31 Â 31 Â 23 nm and containing approximately from 600 000 to 1 400 000 Ag atoms, were used depending on the projectile cluster size and impact energy. The interactions between the cluster atoms, Ar-Ar, and between the cluster atoms and the substrate atoms, Ar-Ag, were described by the Lennard-Jones potential splined with the KrC potential to account properly for high-energy collisions.…”

Section: Computationalmentioning

confidence: 99%

“…To improve the statistical relevance of the findings, the analysis was based on MD trajectories that have sputtering yields close to the average values for given beam conditions. 20 The calculations were performed at 0 K.…”

Section: Computationalmentioning

confidence: 99%

Physical basis of energy per cluster atom in the universal concept of sputtering

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

Postawa

Garrison

2016

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High-energy ions and atoms sputtered and reflected from a magnetron source for deposition of magnetic thin films J.The interpretation of the variables, scaled by the number of projectile cluster atoms n, in the universal relation of the sputtering yield Y versus incident energy E, that is, Y/n vs E/n, is not necessarily obvious. Following on previous works, the objective of this study is to elucidate the physical basis of the energy per atom variable E/n. The authors employ molecular dynamics simulations of Ar n cluster bombardment of Ag(111) metal samples for this study. The authors find that the energy per cluster atom quantity E/n is responsible for the fraction of the initial energy that is deposited in the solid, rather than energy per cluster mass E/m. The results show that even though there is an average loss of the energy for a cluster, each cluster atom loses a different fraction of its initial energy, thus yielding a distribution of energy loss by individual atoms. The analysis of these distributions indicates that the energy deposition process is more effective for clusters with higher E/n when compared to the clusters with lower E/n. This conclusion is supported by a visual analysis of the cluster bombardment event. The cluster atoms that lose most of their initial energy are those which split off from the cluster and penetrate into the bulk of the solid. Conversely, the atoms of the clusters with low E/n keep together during the interaction with the solid, and eventually reflect into the vacuum taking away a portion of the initial kinetic energy. In addition, the simulations indicate that the clusters of different sizes have the same distribution of energy loss for individual atoms if they have the same E/n, in other words, if the initial energy E is proportional to the cluster size n.