Deposition of hydrogenated amorphous silicon (a‐Si:H) films is performed by low‐frequency (50 Hz) plasma‐enhanced chemical‐vapor deposition (PECVD). The results show that the undopeda‐Si:H films deposited at a substrate temperature of 200 °C are high‐quality films comparable to those deposited by conventional rf PECVD at a substrate temperature of 300 °C. The photoconductivity and dark conductivity of the films are 4 × 10−4S/cm and 5 × 10−9S/cm respectively. The activation energy is 0.78 eV and the optical gap is 1.8 eV. Furthermore, it is possible to control the dark conductivity and activation energy by doping with substitutional impurities of boron and phosphorus. These properties are very similar to those of thea‐Si:H films deposited by conventional rf PECVD in the optimum substrate temperature range from 250 to 300 °C. These results show that the 50 Hz PECVD can deposit high‐qualitya‐Si:H films.