Dual-gate ITZO/IGZO heterojunction thin-film transistor with enhanced mobility and stability

Abstract We demonstrate a dual-gate (DG) indium–tin–zinc–oxide (ITZO)/indium–gallium–zinc–oxide (IGZO) heterojunction thin-film transistor with excellent electrical performance and bias-stress stability. In the DG heterojunction device, stacking IGZO on ITZO forms a two-dimensional electron gas (2DEG) at the interface, resulting in a field-effect mobility ( μ FE ) of 62.18 cm 2 /Vs, far exceeding that of bottom gate (BG) single-channel and BG heterojunction devices. This enhanced μ FE results from both 2DEG formation and stronger carrier confinement enabled by the DG structure. The DG heterojunction device also shows superior stability under positive bias temperature stress, negative bias temperature stress, and negative bias illumination stress. This enhanced stability is attributed to the electric-field offset effect, where opposing top- and bottom-gate fields reduce net bias stress and suppress charge trapping. These results highlight the promise of DG heterojunctions for high-performance, reliable oxide electronic devices.