Transparent and Flexible Thin‐Film Transistors with High Performance Prepared at Ultralow Temperatures by Atomic Layer Deposition

Abstract High‐performance, transparent, and flexible thin‐film transistors (TFTs) with polycrystalline channels in a bottom‐gate structure are successfully fabricated at extremely low temperatures of 80, 90, and 100 °C by atomic layer deposition (ALD) in which ZnO and Al₂O₃ are used as channels and dielectric layers, respectively. The transistors are superior to silicon‐based TFTs in which high temperatures are necessarily involved in both preparation and postgrowth annealing. Among all devices, TFTs grown at 100 °C exhibit the best performance which can be attributed to the lowest grain boundary trap density. Additionally, the TFTs are successfully transferred to plastic substrates without any performance degradation, which shows a high mobility of 37.1 cm²V⁻¹ s⁻¹, a high on/off‐state current ratio of 10⁷ at V_DS = 0.1 V, a small subthreshold swing of 0.38 V dec⁻¹, and a proper threshold voltage of 1.34 V as well as an excellent bias stability.