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

epresents a small improvement over the surface approximation method as it closer
describes the physically occurring situation. A variation of 2-3% over a depth of 10nm
has been observed between the two methods.
Other ways to calculate the depth scale are based on analytical methods. These
are based around solving equations for the distance based on expressions for dE/dx (4)
but were not used in this project.
4.2.1.4 Surface Approximation method
A schematic of the MEIS scattering configuration is shown in Figure 4.2. An ion
of energy E0, scattered at the surface loses energy elastically and has a resulting energy
KE0. An ion scattered from a depth of ∆z inside the sample travels a path length of
∆z/cosθ1 through the sample before an elastic collision and travels a distance of
∆z/cosθ2 on the exit path, losing energy inelastically along both paths in addition to the
energy lost in the collision.
E2
∆ z
E1
x2
Ef
θ2
Si
x1
θ1
Figure 4.2 MEIS scattering configuration.
K 2 E0
KE0
Over the small depth range used in MEIS, the variation in the rate of inelastic
energy loss per distance is comparably small and as an approximation can be assumed
to be constant along each path (4). In the collision with a lattice atom the ion undergoes
an elastic energy loss and therefore the rate of inelastic energy loss takes a different
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E0