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

with are comparatively small, ~ 0.5 nm, but effort was put into this area in an effort to
maximise the high resolution potential of the technique.
4.2.3.1 Stopping powers
At an early stage it was observed that a variation of up to 9 % existed between
depth profiles converted from MEIS spectra taken on the same sample using 100 keV or
200 keV He + beam energies. An example of these depth profiles is shown in the top of
Figure 4.17, including data taken using a 150 keV beam. The discrepancy in the peak
centres is indicated with dashed lines. The cause of this discrepancy was an incorrect
slope of the inelastic loss curve. There have recently been a number of studies with the
aim to improve the accuracy of stopping powers (32, 33, 34, 35). The solution that
produced consistent depth scales was found with the release of the 2003 version of
SRIM. The stopping powers have been significantly improved from the last major
update in SRIM 1998 (20). The updated energy loss rates are compared with those of
the SRIM 2000 version in Figure 4.18. The use of the new inelastic loss data largely
eliminated the discrepancy at the two energies as demonstrated in the depth profiles in
the bottom of Figure 4.17.
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