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 11B 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 11B 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, Se, for axial channeling ranged from 3.56 × 10−14 eV-cm2/atom for the [Formula: see text] axis to 4.88 × 10−14 eV-cm2/atom for the [Formula: see text] axis, at. an ion velocity of 1.5 × 108 cm/s. Se was significantly higher for the {111} plane than for the [Formula: see text] axis, but equal to Se for the [Formula: see text] axis. The values of Se for the [Formula: see text] and [Formula: see text] axes and the {110} plane were nearly equal. For ions other than 11B, Se was determined for [Formula: see text] channeling and was found to exhibit a strong oscillatory dependence on Z1. For electronic stopping cross sections calculated at an ion velocity of 1.5 × 108 cm/s, maxima in the Se vs. Z1 curve occurred at Z1 = 6 (Se = 4.34 × 10−14 eV-cm2/atom) and Z1 = 17 (Se = 6.76 × 10−14 eV-cm2/atom). The minimum occurred at Z1 = 11, where the value of Se, was 0.57 × 10−14 eV-cm2/atom.