Damage formation and annealing studies of low energy ion implants ...

Taking data creates a data tile, i.e. a 2D plot of the yield at each point on the
analyser. By stepping the pass energy down, and joining together the individual tiles, a
continuous energy spectrum can be produced. Further data processing information is
given in section 4.2.2.3.
4.2.2.2 Experimental Parameters
Before explaining the MEIS output data, the choice of experimental parameters
needs to be discussed. The main experimental parameters to consider are the scattering
angle, which is determined by the crystallographic directions in and out, the beam
energy and the choice of projectile mass. Changes to these parameters produce a variety
of effects and often a compromise is needed to find the best overall conditions.
It is useful to avoid overlap of peaks from different elements (masses) to make
analysing the data more straightforward and to avoid ambiguity of the results. This may
be achieved by choosing conditions with a sufficiently large variation in the kinematic
factors (equation 2.10) for all the different elements present in a sample. The kinematic
factor varies with scattering angle and with mass ratio of the atom and incident ion.
Plots of the kinematic factor for various atom / ion combinations are shown in Figure
4.13, for He ions on the left and H ions on the right. There are several important
observations. As the scattering angle is increased, there is an increased variation in K
between the different masses hence there is less likelihood of peak overlap at larger
scattering angles. There is less variation for high masses than light elements.
Comparison between He and H shows a much larger spread of K values achieved with
He.
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