The Role of Dual-Stacked Oxide Semiconductor in High Performance Thin Film Transistors
Abstract Oxide thin film transistors (TFTs) have attracted much attention because they can be applied to flexible and large-scaled switching devices. Especially, Oxide semiconductors (OSs) have been developed as active layers of TFTs and, among them, Indium-Gallium-Zinc-Oxide (IGZO) is actively used in the OLED display field. However, IGZO TFTs are limited by low field-effect mobility, which critically affects display resolution and power consumption, despite superior off-state properties. Herein, we prevailed new working mechanisms in dual-stacked OS and, based on this, developed dual-stacked OS-based TFT with high field-effect mobility (~80 cm2/V·s), ideal threshold voltage near 0 V, high on-off current ratio (>109), and good stability at bias stress. In dual-stacked OS, induced areas are formed at interface by band-offset: band-offset-induced area (BOIA) and BOIA-induced area (BIA). They connect gate-bias-induced area (GBIA) and electrode-bias-induced area (EBIA), resulting in high current flow. Such mechanism will provide new design rules for high performance OS-based TFTs.
