The effects of applied bias voltage on structure and hydrogen content of a-C:H films

a-C:H films were prepared by the DC-RF PECVD technique. The variation of the structure and hydrogen content of the films versus the applied DC bias voltage were studied by FTIR and Raman scattering spectroscopy. The results showed that the structure of the films tended to be more graphite-like when at either a higher or a lower applied DC bias than at -800 V. The hydrogen content (total amount of both bonded and unbonded) of the films was found to have a maximum value at about -800 V. The results are discussed and compared with those reported in the published literature.