Scaling behaviour of a-IGZO TFTs with transparent a-IZO source/drain electrodes

We analysed the scaling behaviour of amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) with amorphous indium zinc oxide (a-IZO) transparent source/drain (S/D) electrodes. Due to the sputtering damage of the back-channel region during the a-IZO deposition process, the output characteristics show early saturation behaviour and the field-effect mobility in the saturation region is severely decreased in comparison with that in the linear region, especially when the channel length is decreased. Based on the transmission line method, we found that a long gate overlap distance is required due to the long current transfer length. Therefore, optimizing the parasitic resistance is required for the scaling down of a-IGZO TFTs with transparent a-IZO S/D electrodes.