Behavior of deuterium in boron films covered by oxygen-containing layer

The behavior of deuterium in boron films covered by an oxygen-containing layer was studied by means of XPS and TDS. The pure boron films were deposited on a Si substrate by plasma chemical vapor deposition (PCVD) using a mixture of the gases, decaborane (B10H14) and helium, and two kinds of boron films covered by oxidized boron layer were prepared on pure boron films by PCVD using B10H14, He and O2, and by oxidation using O2 + He plasma, respectively. Boron films were irradiated by 3 keV D 2 + at a flux of 1 × 1018 D+ m−2 s−1 up to 1 × 1022 D+ m−2. It was found that less oxygen in the surface layer of the boron film can reduce the deuterium retention and the oxygen in the boron film is preferentially sputtered by deuterium ions due to chemical reactions between deuterium and oxygen during the D 2 + irradiation.