The microstructure and electrical properties of μc-Si and μc-Si,C prepared by remote plasma-enhanced chemical-vapor deposition, PECVD, are reviewed. The microstructure has been characterized by transmission electron microscopy, TEM, infrared, IR, absorption and Raman scattering. The electrical properties were characterized by temperature-dependent dark-conductivity measurements. These studies have explained significant quantitative differences between the carrier transport properties of μc-Si and μc-Si,C alloys in terms of a band offset model for the interfacial potential steps between the amorphous and crystalline constituents of these material systems.