Thermal spikes and sputtering yields

Johnson, R. E.; Evatt, R.

doi:10.1080/00337578008210031

Cited by 97 publications

(15 citation statements)

References 7 publications

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“…For linear cascades, when the density of moving atoms N mov within the cascade is small compared to normal density N 0 , one has nϭ1, 2,3 whereas in the nonlinear case, N mov ϳN 0 , theoretical work predicts that n must be greater than 1. 4,5 These results are so firmly established that the consensus among workers in the field is that nϾ1 and nonlinear cascades are to some extent synonymous. 6 Similar results have been found for sputtering in response to electronic energy deposited in a solid, 7 but here we refer to work on collision cascade sputtering.…”

Section: Introductionmentioning

confidence: 74%

Fluid dynamics calculation of sputtering from a cylindrical thermal spike

2002

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The sputtering yield Y from a cylindrical thermal spike is calculated using a two-dimensional fluid-dynamics model which includes the transport of energy, momentum, and mass. The results show that the high pressure built up within the spike causes the hot core to perform a rapid expansion both laterally and upwards. This expansion appears to play a significant role in the sputtering process. It is responsible for the ejection of mass from the surface and causes fast cooling of the cascade. The competition between these effects accounts for the nearly linear dependence of Y with the deposited energy per unit depth that was observed in recent moleculardynamics simulations. Based on this we describe the conditions for attaining a linear yield at high excitation densities and give a simple model for this yield.

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Section: Introductionmentioning

confidence: 74%

Fluid dynamics calculation of sputtering from a cylindrical thermal spike

2002

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“…͑10a͒-͑10c͒, either a point spike in which ion energy was deposited instantaneously or a line spike along which energy was deposited instantaneously defined the initial geometry as in a number of previous studies. 48,[70][71][72][73][74] As indicated earlier, at the end of the collisional stage following ion impact, energy will be equilibrated throughout the volume of the collision cascade, and an effective maximum temperature of atoms in this volume can be assigned. This can form a different initial condition from the point or line geometry defined above.…”

Section: Discussionmentioning

confidence: 99%

“…This equation has been solved, for constant values of these thermal parameters, exactly 69 and in a useful approximation; 70 and for conditions where the ratio of the thermal conductivity to the heat capacity ͑the thermal diffu-sivity͒ was assumed to be a simple power-law function of temperature 71,72 or where both parameters were assumed to be independent and different power-law functions of temperature. The rate per atom or defect at which a thermally activated process occurs is given by 0 exp(ϪQ/kT).…”

Section: The Influence Of Thermal Spikes On Atom and Defect Jumpmentioning

confidence: 99%

Influence of thermal spikes on preferred grain orientation in ion-assisted deposition

Carter

2000

Phys. Rev. B

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Theoretical models are presented to explain how thermal spike processes can induce the development of preferred orientation of polycrystalline grains during ion-assisted atomic deposition and thin film growth. Two ion energy regimes are investigated. In the first, higher-energy regime, ions penetrate growing grains and generate defects at rates dependent upon the probability of ion channeling in individual grains. The volume free-energy density of different grains is, therefore, different and the thermal spike arising from each ion impact results in preferential growth of grains with the lowest volume free-energy density. In the second, lower-energy regime, ions do not penetrate nor create defects in grains but the ion-induced thermal spikes centered on the surface can enhance surface atomic migration and lead to preferential growth of grains with the lowest surface free-energy density. The results in these two regimes are compared with the predictions of a model for preferred grain orientation evolution in the absence of ion assistance and where minimization of surface free-energy density is the driving process. Ion energy, ion flux density, depositing atom flux density, and system temperature conditions are established where ion-assisted and non-ion-assisted rates of preferred grain orientation become comparable. It is shown that, in general, the tendency toward preferred orientation is not a simple function of the energy per deposited atom.

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“…similarly as in the Sigmund-Claussen approach for sputtering by elastic-collision spikes [19,20] and in the Johnson-Evatt thermal spike model [30]. In this expression, U is the evaporation rate, given by:…”

Section: Thermal Spike Model Calculationsmentioning

confidence: 97%