In this work, a Si:H films with good electronic properties in spite of an inhomogeneous structure were prepared by the 55 Hz plasma enhanced chemical vapor high-rate deposition technique. The structural analysis using infrared spectroscopy and atomic force microscopy has shown that these films possess two dominant types of microstructural inhomogeneities, which differ by size. To analyze the influence of a 55 kHz plasma on the properties of intrinsic a-Si:H film, the density of states in the a-Si:H mobility gap was estimated by modeling of the temperature dependence of the photoconductivity and from electron paramagnetic resonance measurements. Investigated capacitance-voltage characteristics showed that a-Si:H/c-Si heterostructures have low interface density of states and can be considered as an ideal abrupt heterojunction.