- A new type of trilayer amorphous silicon (a-Si:H) thin film transistor (TFT) is presented in this paper. It also has a self-aligned source/drain-to-gate configuration and uniformly narrow source/drain vias. The finished transistor shows an on/off current ratio greater than 107 and the on-current is proportional to the channel width-to-length ratio. Compared with a conventional single-channel TFT that occupies the same area, this new TFT has a higher channel width-to-length ratio and a higher on-current. The physical limitations of the new TFT, based on the current large area lithography tool, are also discussed. This TFT can be applied to displays and imagers that require a high on-current and a low area occupancy.