A new self-aligned TFT structure that requires two photomasks is described in this paper. Three process steps, i.e., the bacldight lithography, the top dielectric etch, and the n + etch, have been studied in detail. The finished ~ has transfer characteristics and Id -Vd curves similar to those of a TFT prepared from a more complicated conventional process. TFT structure parameters, such as the channel length, the a-Si:H thickness, the source/drain via size, and the contact resistance, affect the field effect mobility and the Io,/Io~ratio. These relations were examined. Including a Ta205 thin layer in the gate dielectric structure changes the device characteristics. The relation between the Ta20~ process and the device has been studied.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.233.5.201 Downloaded on 2015-01-03 to IP