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

similar to the width of the error function, then the resulting convoluted peak will have a
FWHM that will be subject to some broadening, as shown in Figure 4.9c). If the slope
of an interface is broad compared to the limits imposed due to the convoluting Gaussian,
then the resulting convoluted spectra will closely follow the shape of the interface, as
shown for the interface at low energy in Figure 4.9d).
Yield (%)
100
80
60
40
20
0
100
80
60
40
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0
a) b)
c)
Energy
4.2.2 Experimental
4.2.2.1 MEIS system
A diagram of the Daresbury MEIS facility (3) is shown in Figure 4.10 and the
system is also described in (43). The ion source platform houses a duoplasmatron ion
source. He + or H + ions are accelerated with an energy of 20 keV from the source and
then the ions are then accelerated again to the required energy with a second power
supply. Originally a 500 kV power supply was used but this was replaced with a 250 kV
supply, with better voltage stability and which could be set with more accuracy.
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d)
Ideal
Convoluted
Figure 4.9 The effect of convoluting different ideal peak shapes with a single Gaussian
function. a) A layer that is wide compared to the width of the Gaussian. b) A very thin
layer. c) A layer with a width similar to the Gaussian. d) An interface with a broad
energy distribution.