EFFECT OF THE SPACE-CHARGE SHEATH ON PROPERTIES OF CARBON AND DIAMONDFILMS IN THE RF PLASMA-JET

Glassy carbon and diamond films were grown by an r.f. low pressure sup ersonic plasma jet. The effect of ion bombardment through the space ch arge sheath (e.g. by CH + ions) on the resulting film properties was s ubstantially reduced by using an auxiliary mesh electrode to shield th e substrate from the r.f. plasma jet. A positive d.c. potential on the substrate with respect to the mesh electrode was used to reduce the e nergy of ions passing the sheath towards the growing film. As a result a pronounced diamond peak at 1335 +/- 5 cm-1 appeared in the spectra corresponding to the biased case.