Abstract
Photocurrent transients have been measured in hydrogenated and unhydrogenated (as-deposited) polycrystalline silicon thin-film transistors as a function of gate voltage. For both types of samples, the transients demonstrate dispersive transport and a gate voltage independent shape over a large range of gate voltages. The multiple trapping model for trap controlled transport has been used to develop a schematic model for the gap states. According to this model, the major effect of hydrogenation is the removal of shallow trapping states and it is also accompanied by a small change in dangling bond spin density.