Analytical modeling of atomic-number-dependent electronic stopping cross sections in Si, C, 4H-SiC, Al, Ni, and Ag

Atomic number (Z1) dependencies of electronic stopping cross sections (Se) for channeling trajectories had been well explained for low-velocity ions; however, this is not the case with Se for random trajectories (Serandom). We modeled the difference between the effective atomic number for random trajectories and that for channeling ones (Z ') changing linearly with the difference between the actual atomic number and Z '. The proportionality constant k for Serandom in Al, Ni, and Ag for 1.8 x 108 cm s-1 ions was found to depend little on the target atomic number. k for Serandom in 4H-SiC for 1.5 x 108 cm s-1 ions, on the other hand, located between k for Serandom in Si for 1.5 x 108 cm s-1 ions and k determined from that for 1.4 x 108 cm s-1 ions in C and that for 2.0 x 108 cm s-1 ions in C.