Channeling of medium-mass ions through silicon

The channeling of ions with Formula: see text through thin (0. 24-1. 5 μ) silicon samples has been studied for ion energies ranging from about 100 keV to 500 keV. The effects of radiation damage and sample misorientation on the energy spectrum and angular spread of the transmitted ions have been observed for Formula: see text channeling, using 11 B projectile ions. Electronic stopping cross sections for well-channeled ions have been calculated from measurements of the maximum energy of the transmitted ions as a function of their incident energy. For 11 B these measurements have been made for channeling along the Formula: see text, Formula: see text, Formula: see text, and Formula: see text axes and between the 111, 110, and 100 planes. The value of the electronic stopping cross section, S e, for axial channeling ranged from 3. 56 × 10 −14 eV-cm 2 /atom for the Formula: see text axis to 4. 88 × 10 −14 eV-cm 2 /atom for the Formula: see text axis, at. an ion velocity of 1. 5 × 10 8 cm/s. S e was significantly higher for the 111 plane than for the Formula: see text axis, but equal to S e for the Formula: see text axis. The values of S e for the Formula: see text and Formula: see text axes and the 110 plane were nearly equal. For ions other than 11 B, S e was determined for Formula: see text channeling and was found to exhibit a strong oscillatory dependence on Z 1. For electronic stopping cross sections calculated at an ion velocity of 1. 5 × 10 8 cm/s, maxima in the S e vs. Z 1 curve occurred at Z 1 = 6 (S e = 4. 34 × 10 −14 eV-cm2/atom) and Z 1 = 17 (S e = 6. 76 × 10 −14 eV-cm 2 /atom). The minimum occurred at Z 1 = 11, where the value of S e, was 0. 57 × 10 −14 eV-cm 2 /atom.