In this study the parameters characterizing the electronic transport in glow-discharge deposited amorphous (a) Si:H, a-Si:C:H and a-Si:Sn:H films are investigated For the investigation five experimental techniques are employed. These are the photocurrent reversal, time-of-flight, charge collection, junction recovery and surface photovoltage experiments. In the photocurrent reversal experiment the on-going dispute concerning the magnitude of the drift mobilities in a-Si:H is addressed. It is established that the current transients observed in this type of experiment are due to the drift of photogenerated excess carriers. The details of the results are in excellent agreement with the low mobility picture which has been gained by means of transient photoconductivity experiments. In the time-of-flight and charge collection measurements, the drift mobilities, carrier ranges, capture cross-sections for shallow and deep trapping, and the distribution of bandtail states are determined. The origin of the deep trapping states and their role in the Staebler-Wronski effect are discussed. For the first time a detailed description of the junction recovery experiment applied to a-Si:H p-i-n type diodes is given. The recombination process relevant to this experiment is discussed and hole recombination times of the order of 10 ns are measured for double injection conditions. These values are consistent with typical hole diffusion lengths measured in the surface photovoltage method. On the basis of the transport parameters derived a possible distribution of the energy levels for the dangling bond states in a-Si:H is discussed The a-Si:Sn:H and a-Si:C:H films are investigated by means of the charge collection technique. A comparison to the results obtained with the a-Si:H films reveals a strong degradation of the electronic properties in the alloy films and indicates the emergence of a new defect center in the atomic network of these alloys