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

For an idealised peak, shown in Figure 4.8a), the effect of the energy straggling
is to broaden the low energy edge of the peak, as is shown in Figure 4.8 b). The effect
of the system resolution is to broaden both the leading edge and the low energy edges,
as shown in Figure 4.8c). The overall effect is to convolute the ideal peak with the
Gaussian distributions. Note that Ω’s add together quadratically, i.e. Ωs+r = √( Ωs 2 + Ωr 2 ).
Figure 4.8 The effects of energy straggling and the system
resolution. For an ideal profile a), energy straggling causes
a broadening of the low energy edge b). The system
resolution causes a broadening of both the leading and low
energy edges c). From (4).
The impact of the convolution depends on the details of the layers being studied.
In Figure 4.9 various ideal peak shapes have been convoluted with a single Gaussian to
illustrate the effects. If the width of the layer is wide compared to the convoluting
Gaussian, then the layer width can be taken as the FWHM of the convoluted spectrum,
as shown in Figure 4.9a). The low and high energy edges are broadened however. The
interface sharpness cannot be measured to exceed that determined by the limit imposed
by the energy straggling and resolution limit. If a layer is thin compared to the
convoluting Gaussian, then the resulting peak will take the form of the Gaussian. The
true position of the signal on the energy axis is given by the energy where the Gaussian
has its maximum, as in Figure 4.9b). If the real layer width is some intermediate value
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