Growth of amorphous hydrogenated silicon (a-Si:H) films away from so-called standard conditions have recently assumed great importance for extending the range of applications or perhaps even to improve the performance of presently available a-Si:H material. In the present investigation by depositing such films on the cathode of an asymmetric r.f. plasma-enhanced chemical vapour deposition reactor, without any deliberate substrate heating, we could ascertain those conditions where as-grown films show preferentially IR absorption peaks centred around 2000 cm(-1). Further, under hydrogen dilution of the feedstock and inducing high self-bias values, by essentially inputting a high r.f. power to the cathode, we find that photoconductivity of the films produced show an order of magnitude change (sigma(ph) approximate to 10(-6) Omega(-1) cm(-1)). A systematic photothermal deflection spectroscopy study has been undertaken to follow the change in a-Si:H film properties through manipulation of the plasma conditions. Implications of the present results are critically examined in the light of other related available information and existing models of growth.