Method to Extract Interface and Bulk Trap Separately Over the Full Sub-Gap Range in Amorphous InGaZnO Thin-Film Transistors by Using Various Channel Thicknesses

We propose an experimental method to decompose the interface (insulator/channel) trap density ( ${D}_{\mathrm {it}}$ ) and sub-gap density-of-state in the entire defect ( ${g}_{\mathrm {tot}}$ ) of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). This method involving various active layers of different thicknesses is used for determining the origin of defects and for process optimization. These results can be used to determine clearly the contributions to the origin of the defect. Oxygen-related and deep states near the conduction band minimum ( ${E}_{{C}}$ ) were strongly affected by the interface region. Tail states near ${E}_{C}$ , on the other hand, were strongly influenced by the active layer. The proposed method provides physical insight and key guidelines for optimizing the performance of a-IGZO TFTs.