Channeling of medium-mass ions through silicon

Abstract

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.