Implanted hydrogen isotope retention and chemical behavior in boron thin films for wall conditioning

The behavior of hydrogen isotopes in boron was studied by XPS and TDS. The samples used were boron polycrystals and boron thin films produced by plasma CVD using decaborane (B10H14) diluted by He gas. The 1.0 keV deuterium ions were implanted into the samples up to fluence of 5.4 × 1021 D m−2 at various temperatures. It was found that deuterium retention at 573 K was decreased less than 35% compared to that at room temperature. The activation energies for B–D–B and B–D bonds were estimated to be 1.11 ± 0.21 and 2.17 ± 0.36 eV for the boron thin film, and 1.36 ± 0.20 and 2.27 ± 0.45 eV for the boron polycrystal, respectively. The B–H distance and the activation energy for the B–H bond were also calculated by the Gaussian 03 code and these were consistent with the experimental values.