The effects of discharge parameters on the properties of hydrogenated silicon-carbon films deposited by PECVD system have been investigated. Hydrogenated microcrystalline silicon-carbon films have been grown at low RF power. The increase in RF power from 5 to 25 W leads to a decrease of the crystallinity degree and an enhancement of the carbon content from 0.025 to 0.10. The optical energy gap can be tuned in the 1.86-1.96 eV range and the dark conductivity decreases by about three orders of magnitude. In the investigated pressure range (1.7-2.9 Torr) microcrystalline samples show approximately the same optical and electrical properties. Microcrystalline films with high dark conductivity present an n-type character and the micro-mono crystalline silicon heterostuctures fabricated with these materials reveal a rectifying behaviour of the junctions. (c) 2004 Elsevier B.V. All rights reserved.