P‐8: The Analysis of Effective Channel Length in a‐IGZO TFTs with the Top IGZO layer

We investigated the effective channel length (L eff ) of a‐IGZO single layer and bi‐layer. In the I‐V curve, the drain‐induced barrier lowering (DIBL) phenomenon appeared to be severe in the single layer, while it was relatively improved in the Bi layer. Based on this, we have determined the effective channel length through transmission line method (TLM) and confirmed that the effective channel length of the Bi layer is longer. The threshold voltage variation for each design length from 3.5 to 8.5 μm was also smaller in the Bi‐layer. The results of XPS analysis show that this was due to the oxygen decomposition by Ti. In the Bi‐layer with Ga‐rich top layer, the high conduction region due to the oxygen decomposition phenomenon was reduced.