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

thermal annealing (600 – 700 °C and form small aggregates of Si interstitials, with the
most stable “magic” clusters being made up of 4 and 8 atoms (55). For longer anneal
times and higher temperatures, the excess interstitials condense into extended defects
(56). This category of defects consist of {113}’s, perfect dislocation loops (PDL’s) and
faulted dislocation loops (FDL’s) and TEM images of each are shown in Figure 3.9.
Figure 3.9 TEM images of defects present in the
EOR damage area of ion implanted Si. These are
clusters, {113}s, PDLs, and FDLs. From (56).
{113} rod like defects are formed from smaller clusters and can become visible
in a TEM from lengths of 2 nm (57). The {113} defects are bundles of rows of Si diinterstitials
that lie on {113} planes and which are elongated along directions
and consist of condensates of interstitials forming five and seven – membered rings (58).
This atomic arrangement provides a way to insert planes of self interstitials without
dangling bonds (58). They have a constant width of 4 nm. Once {113} defects are
formed, further annealing can make the larger {113}’s grow in size at the expense of the
smaller ones, thereby reducing the density of {113}’s.
Dislocation loops form in the most densely packed crystal planes for reason of
energy minimisation. Typically the loops consist of circular extra {111} planes of Si
interstitials with the lattice elongated along directions. Perfect dislocation loops
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