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

For the sample annealed at 650 °C, where there is a major change in the MEIS
profile the differences between the results from the two techniques are clearly visible.
The SIMS profile shows a great deal of extra As from a depth of 4 – 12 nm and this, as
argued above, must represent substitutional As. For the 0 – 4 nm depth range the SIMS
profile is higher than the MEIS profile. This is most likely due to the comparatively
large uncertainty in the calibration of the concentration in SIMS. A similar picture is
seen with the sample annealed at 700 °C. The segregated peak has tightened up as seen
in both MEIS and SIMS, and again SIMS probably overestimates the segregated peak
concentration. However the substitutional fraction from 4 – 12 nm can be clearly seen.
As concentration (at/cm 3 )
4.0x10 21
3.5x10 21
3.0x10 21
2.5x10 21
2.0x10 21
1.5x10 21
1.0x10 21
5.0x10 20
0.0
a)
600°C 10s MEIS
600°C 10s SIMS
0 2 4 6 8 10 12 14
b)
2 4 6 8 10 12 14
Hall effect measurements were carried out on these samples, and the results are
given in Figure 6.18. The sheet resistance was as low as 610 Ω/□ for the sample
annealed at 650 °C for 10s. The 700 °C had a slightly higher Rs value of 684 Ω/□. It is
suggested that this could be due to As clustering at the higher temperature. From these
measurements the activated dose can be obtained and this was found to be in the region
of 2.2E14 -2.4E14 cm -2 which is in reasonably good agreement with the values that
could be obtained from the shoulder height in the SIMS comparison in Figure 6.17,
which lends support to the validity of the comparisons.
149
650°C 10s MEIS
650°C 10s SIMS c)
Depth (nm)
Figure 6.17 MEIS and SIMS combined depth profiles.
700°C 10s MEIS
700°C 10s SIMS
2 4 6 8 10 12 14