Plasma immersion ion deposition (PIID) has been used to synthesize hard amorphous hydrogenated carbon or diamondlike carbon (DLC) thin films on Si substrates with rf inductive plasmas of various Ar and C2H2 gas mixtures. The surface hardness and stress-of the films were highly dependent on the magnitude of the total rf power and the pulse-bias duty factor. The ratios of the ion flux and the film deposition flux, J(i)/J(d), were estimated and correlated with DLC film stress, hardness, and the amount of argon and hydrogen content retained. The DLC properties (hardness and film stress) were maximal when the J(i)/J(d) value ranged between 0.6 and 0.8. The balance between ion-energy transfer and relaxation in the surface and subsurface carbon atoms may explain the DLC growth in this work. The role of ion-current flux in the PIID process was found to: be as important as it is in conventional ion beam assisted deposition processing.