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Influence of the polar angle of incidence on secondary ion formation in self‐sputtering of silver
Author(s) -
Weidtmann B.,
Hanke S.,
Duvenbeck A.,
Wucher A.
Publication year - 2011
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.3403
Subject(s) - collision cascade , atomic physics , projectile , ion , ionization , excitation , sputtering , kinetic energy , chemistry , secondary emission , electron ionization , secondary electrons , particle (ecology) , amorphous solid , electron , physics , materials science , thin film , nanotechnology , classical mechanics , oceanography , organic chemistry , quantum mechanics , geology
The influence of the projectile impact angle on secondary ion formation was studied using a computer simulation model applied to the bombardment of an amorphous silver crystal by 5‐keV Ag atoms. The model employs a molecular dynamics (MD) scheme for the description of particle dynamics within the atomic collision cascade. The electronic degree of freedom is treated within the framework of a free electron gas model incorporating kinetic excitation by electronic friction and electron promotion. Transport of the excitation energy away from the spot of generation is treated by a diffusive approach. In combination with a rate equation model for electronic charge transfer an individual ionization probability α + is assigned to each sputtered particle. The results reveal that the average ionization probability of sputtered atoms increases upon the transition from normal to oblique incidence. The dependence of α + on the emission velocity of ejected atoms is traced back to the temporal structure of the excitation profile induced after projectile impact. Copyright © 2010 John Wiley & Sons, Ltd.