Effect of Sc2O3 Passivation Layer on the Electrical Characteristics and Stability of InSnZnO Thin-Film Transistors

We measure the electrical performance and stability of indium tin zinc oxide (ITZO) thin-film transistors (TFTs), respectively, covered with a passivation layer (PVL) of aluminum oxide (Al₂O₃) or scandium oxide (Sc₂O₃) prepared by pulsed laser deposition (PLD). The devices with the Sc₂O₃ PVL exhibit both satisfactory electrical performance and stability with a field effect mobility of 16.4 cm²/Vs, threshold voltage of 1.0 V, subthreshold swing of 0.09 V/decade, and especially, a minimum threshold voltage shift of 0.7 and −1.6 V under negative bias temperature stress (NBTS) and positive bias temperature stress (PBTS), respectively. This may be attributable to the suppression of oxygen vacancy formation and excellent capacity to protect the channel from environmental effects. Although the devices with the Al₂O₃ PVL show similar electrical performance, their stability is worse than that of the devices with Sc₂O₃. This shows the excellent potential of Sc₂O₃ thin films as a PVL.