Sputtering Yields for Mixtures of Organic Materials
Using Argon Gas Cluster Ions
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Abstract
The
sputtering yield volumes of binary mixtures of Irganox 1010
with either Irganox 1098 or Fmoc-pentafluoro-l-phenylalanine
(FMOC) have been measured for 5 keV Ar<sub>2000</sub><sup>+</sup> ions
incident at 45° to the surface normal. The sputtering yields
are determined from the doses to sputter through various compositions
of 100 nm thick, intimately mixed, layers. Because of matrix effects,
the profiles for secondary ions are distorted, and profile shifts
in depth of 15 nm are observed leading to errors above 20% in the
deduced sputtering yield. Secondary ions are selected to avoid this.
The sputtering yield volumes for the mixtures are shown to be lower
than those deduced from a linear interpolation from the pure materials.
This is shown to be consistent with a simple model involving the changing
energy absorbed for the sputtering of intimate mixtures. Evidence
to support this comes from the secondary ion data for pairs of the
different molecules. Both binary mixtures behave similarly, but matrix
effects are stronger for the Irganox 1010/FMOC system