Argon ion-induced dissociation of acetylene in an expanding Ar/C2H2 plasma

Mass spectrometric and Langmuir probe measurements reveal that the plasma c hemistry of an expanding Ar/C2H2 plasma which is used for deposition of hyd rogenated amorphous carbon is dominated by argon ion-induced dissociation o f the precursor gas. The ion-induced dissociation is very efficient leading to complete depletion under certain conditions. The ion fluence as determi ned from modeling the mass spectrometry results is in good agreement with L angmuir probe measurements suggesting a one-to-one relation between the arg on ion and acetylene consumption. The good correlation found between the gr owth rate and the acetylene consumption rate expresses the efficient use of the dissociation products. (C) 1999 American Institute of Physics. [S0003- 6951(99)02820-X].