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Study of charge effect during Cs + sputtering of polystyrene in the pre‐equilibrium regime
Author(s) -
Wahoud F.,
Mouhib T.,
Audinot J.N.,
Delcorte A.,
Migeon H.N.
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.3419
Subject(s) - sputtering , fluence , polystyrene , materials science , insulator (electricity) , dielectric , substrate (aquarium) , voltage , surface charge , electric field , analytical chemistry (journal) , electrical conductor , thin film , charge density , optoelectronics , condensed matter physics , ion , chemistry , nanotechnology , electrical engineering , composite material , physics , polymer , oceanography , organic chemistry , engineering , quantum mechanics , chromatography , geology
This study investigates the effect of the insulating nature of polystyrene thin films on the SIMS signal during Cs + sputtering. A threshold primary fluence φ th (∼3 × 10 14 cm −2 for a 150 nm film) marks the transition between different behaviours for charge accumulation/neutralization and their effects on the detected SIMS signal. For Cs + fluences lower than φ th , the voltage difference between the surface and the conductive substrate increases linearly with the film thickness. This voltage difference is due to the accumulation of positive charge on the film surface, which causes a breakdown in the SIMS signal. At fluence φ th , the accumulated charge density induces in the polystyrene film a high electric field permitting to reach the dielectric breakdown voltage, i.e. the minimum voltage that causes a portion of an insulator to become electrically conductive. In this paper, we will suppose that the positive charge, previously accumulated on the surface, could be then neutralized through the conductive regions, which are created in the insulating film. Copyright © 2010 John Wiley & Sons, Ltd.