Range profiles and thermal release of helium implanted into various metals

Abstract

3He+ is implanted at 0.2-340 keV to various fluences between 8 × 1013 and 4 × 1017/cm2 into foils of Ni, Cu, Ag, Au, Pt (fcc), Be, Zr (hex.), Fe, Nb, Mo (bcc), and single crystals of Cu and Nb. The He-3 is detected by the (n,p) reaction of 5kbarn cross section in a thermal neutron flux of about 109/cm2s with a detection sensitivity of about 1 ppm He. The concentration profiles are compared to theoretical predictions of range and damage profiles as obtained by the Monte-Carlo code TRIM. The concentration profiles after thermal release are seen to shift slightly toward the surface. The gas release is found to depend on the total implanted fluence. Only at the very high fluence of 4 × 1017 at./cm2 (54 keV He+ → Cu), the high gas release reported by other authors could be confirmed (experiments by R. S. Blewer et al., theory by W. D. Wilson et al.), while at lower fluences the He was firmly trapped in Cu up to 900°C. Similar behaviour was found for the other fee metals Ag, Au, and Ni. In the hexagonal Be and the bcc metals Nb, Mo and the fcc Pt a gradual onset of Helium release was observed at about 40 to 50% of the melting temperature. © 1979.