The aim of this paper was to present results of the role of the d.c. grid bias on the silane plasma impedance and its I-V characteristics to grow undoped amorphous silicon (a-Si:H) films by plasma enhanced chemical vapour deposition (PECVD) in conditions where some nanoparticles can be formed in the growth region of the deposition process, under proper ion bombardment. The results achieved show that the performances of the films produced are dependent on the self bias voltage that can present photosensitivities of approximately 10(7) (two orders of magnitude larger than the one exhibited by films grown under conventional conditions) with density of states determined by the constant photocurrent method below 4 x 10(15) cm(-3). Apart from that, the films grown are less affected by light soaking than the conventional films.