Electrical properties of top-gate oxide thin-film transistors with double-channel layers

Using ZnO, and three compositional In2O3-Ga2O3-ZnO (IGZO, In:Ga:Zn=1:1:1, 2:1:2, 2:2:1, atomic ratio) semiconductors, we have made and evaluated several double layered oxide thin-film transistors (TFTs). The drain current was mainly affected by the nearer channel material to a gate insulator. From the positive bias stress (PBS) tests, however, the electrical stability showed a complicated result, depending on both channel structures and post-heat treatments.