Chemistry Reference
In-Depth Information
The term ''heat spike'' has been used to describe the dense mixture of atoms
and defects in motion in the core volume (Fig.
6.7
) of a collision cascade. Electron
microscopy pictures suggests that a heat spike in a semiconductor can lead to the
creation of small amorphous zones in semiconductors associated with individual
implanted atoms. There is certainly ample evidence that the accumulation of
implantation defects can lead to the creation of amorphous layers inside the
semiconductor. Implantation at higher temperature can avoid the creation of such
amorphous layers and is more effective than post-implantation annealing at this
temperature after an amorphous layer has been formed.
6.1.4 Hyperfine Interactions
Hyperfine interaction techniques with implanted radioactive probe atoms turned
out to offer a wealth of information to study the atomic configuration and possible
defect association of implanted probe atoms. Several hyperfine interaction tech-
niques, e.g. Mössbauer Spectroscopy, Perturbed Angular Correlations, Low
Temperature Nuclear Orientation, Muon Spin Rotation, and Beta-NMR are
making use of implanted radioactive probe atoms. We refer to the proceedings of
the Hyperfine Interaction Conferences, held every two or three years, for reports
on many of these studies. Except for the earliest conferences, all these proceedings
were published in the journal Hyperfine Interactions.
It is well known to the Mössbauer Spectroscopy community that Mössbauer
probes can be studied in absorption spectroscopy, where the Mössbauer probe
under investigation is present in its stable ground state, and in emission spec-
troscopy, where the Mössbauer probe under investigation is formed in the decay of
a radioactive parent nucleus. By far the majority of Mössbauer studies are in
absorption spectroscopy. Despite the fact that emission spectroscopy studies are
more cumbersome since they require the handling of radioactive parent atoms,
they have the interesting property that low concentrations of probe atoms can be
studied. A very large fraction of Mössbauer ion implantation studies are such
emission spectroscopy radioactive probe studies. A large fraction, indeed, but not
all: in a few interesting experiments both absorption and emission Mössbauer
spectroscopy was used to study the behaviour of some implanted elements in
solids. This tutorial focuses on the use of emission Mössbauer spectroscopy to
study ion implanted systems.
The largest part of the emission Mössbauer spectroscopy work is devoted to
semiconductors since lattice location and defect association are particularly
important there and relevant for semiconductor industry. For a more general
picture of hyperfine interactions in semiconductors, also including non-nuclear
techniques we refer to [
10
]. An overview of Mössbauer studies on semiconductors,
also including diffusion studies and studies where Mössbauer atoms are constituent
atoms of the semiconductor matrix (e.g. ZnTe) can be found in [
11
]. Already in the
1960s implantation studies [
12
,
13
] were performed with radioactive probe atoms
