Table 2 A summary of the implantation and annealing parameters used for the fabrication of the isotopically enriched 28Si samples outlined in this work

From: Highly 28Si enriched silicon by localised focused ion beam implantation

Sample

28Si++ ion fluence [×1019 ions cm−2]

Ion beam current [pA]

Ion beam width [nm]

Annealed

1

(0.84 ± 0.01)

361 ± 3

730 ± 60

No

2

(1.18 ± 0.04)

380 ± 14

730 ± 60

No

3

(1.13 ± 0.01)

340 ± 8

400 ± 60/ 230 ± 30

Yes

4

(1.08 ± 0.01)

330 ± 2

480 ± 6/ 310 ± 30

No

5

(0.84 ± 0.08)

330 ± 2 (~53 %) + 159 ± 2 (~47 %)

320 ± 70

Yes

  1. Each sample was composed of a single localised 22 μm × 22 μm square enriched area and enriched using a 28Si++ focused ion beam accelerated under a potential of 22.5 kV to yield a kinetic energy of 45 keV. Samples 3 and 5 were annealed under an ambient Ar atmosphere using a two-step process consisting of an initial step of 620 °C for 10 min followed by a second step of 1000 °C for 5 s. In instances where significant ion beam astigmatism was present two ion beam width values measured along orthogonal axes are quoted in order to quantify the extent of the beam astigmatism.
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