Nitrogen-Doped Amorphous InZnSnO Thin Film Transistors With a Tandem Structure for High-Mobility and Reliable Operations

The threshold voltage shift (AVth) in amorphous InZnSnO thin-film transistors (a-IZTO TFTs) during negative gate-bias stress (NGBS) is significantly improved by nitrogen doping. Numerous N-In bonds eliminate donorlike subgap states near the Fermi level, which improve stability during stress but degrade electron mobility. We developed tandem TFTs with an a-IZTO:N layer on top of an a-IZTO layer, in which mobility reaches 31.76 ± 0.81 cm 2 /Vs and the reliability is improved. Especially, AVth in NGBS is reduced by 80% for pristine a-IZTO devices. This simple but an effective method achieves fast and reliable operation in the a-IZTO TFTs.