Hydrogen content of amorphous silicon films deposited in a multipole plasma

Hydrogenated amorphous silicon (a-Si:H) samples are prepared in highly controlled conditions in a multipole dc discharge. Hydrogen content of the film is systematically analyzed as a function of deposition parameters such as ion flow, ion bombardment energy Eion, and substrate temperature. Hydrogen atomic concentration and profile are measured by nuclear reaction analysis. The essential role of ion bombardment is emphasized. Increasing deposition temperature and/or decreasing Eion results in a large decrease of the hydrogen content. Hydrogen-enriched surfaces are observed when Eion≲10 eV. It is shown that SinH+m bombardment during film growth produces a dense hydrogen-rich material.