Ion Implantation and Synthesis of Materials - Studium

5.4 ZBL Nuclear Stopping Cross-Section 551S n (ε)0.10.01MoliereLenz-JensenBohrThomas-Fermi0.00110 –5 10 –4 10 –3 10 –2 10 –1 1 10 1 10 2 10 3Fig. 5.2. The universal screening function, Fig. 2.3, can be used to calculate the nuclearstopping power using (5.13). The result is shown in reduced coordinates. Also shown arethe nuclear stopping calculations based on the four classical atomic models (Ziegler et al.1985)εS n (ε) = 6.55 × 10 −3 , so that S n (E 0 ) = 4.58 × 10 −14 (eV cm 2 ) atom −1 . The atomic densityof Si is 5.0 × 10 22 atoms cm −3 so thatdEdxnn 0−1= NS ( E ) = 22.9 eVnm .The reduced energy, ε, in (5.11) and (5.12), is calculated using the universalscreening length, a U , given in (2.17). For calculation purposes, the form of theZBL reduced energy is32.53M2E0ε =ZZ ( M + M ) Z + Z0.23 0.23( )1 2 1 2 1 2,(5.14)where E 0 is in keV. For As incident on Si, the ratio of ε/E 0 = 4.70 × 10 −3 . ForE 0 = 100 keV, ε = 470.