(Invited) Top-Gate Effects in Dual-Gate Amorphous InGaZnO4 Thin-Film Transistors

We discuss the dependence of bottom-gate transfer characteristics (Vbg-Id) on top-gate voltage (Vtg), which we call "top-gate effects", using a-IGZO TFTs having a dual-gate structure. We consider the top-gate effects to be a measure of how a-IGZO TFT characteristics are sensitive to charge generation on TFTs. We compare the top-gate effects in a-IGZO TFTs and conventional channel-etched a-Si:H TFTs. We found that the positive top-gate effect in a-IGZO TFTs varied depending on top-channel properties, while the negative top-gate effect had a similar impact on Vbg-Id characteristics irrespective of top-channel properties. We also found that a-IGZO TFTs had more significant top-gate effects than conventional a-Si:H TFTs.