Polycrystalline InGaO Thin-Film Transistors with Coplanar Structure Exhibiting Average Mobility of ≈78 cm 2 V -1 s -1 and Excellent Stability for Replacing Current Poly-Si Thin-Film Transistors for Organic Light-Emitting Diode Displays.

Highly ordered polycrystalline indium gallium oxide (PC-IGO) film is obtained by the crystallization of room temperature sputtered amorphous IGO on a hot plate at 350 °C for 1 h and then annealed for 1 h in an N 2 O environment. A high-density PC-IGO of ≈7.15 g cm -3 with reduced oxygen vacancy (≈14.83%) and hydroxyl (OH) related defects (≈10.96%) has been obtained by N 2 O annealing. Self-aligned coplanar thin-film transistor (TFT) with the PC-IGO exhibits the average saturation mobility of 78.73 cm 2 V -1 s -1 , threshold voltage of -1.07 V, subthreshold swing of 0.147 V dec -1 , and the on/off current ratio of over 10 8 . The TFTs show excellent stability under bias-temperature stress with a negligible threshold voltage shift (ΔV TH ) of + 0.1 and -0.1 V for the positive and negative bias stresses, respectively. The TFTs exhibit very stable environmental stability when the TFTs are stored under high humidity (85%) and a high temperature (85 °C) for 2 days. The ring oscillator and the gate driver mode of the PC-IGO TFTs exhibit the propagation delay of 7.44 ns/stage with rising/falling times of less than 0.7 μs, respectively. Therefore, the PC-IGO TFTs are suitable for large area, high-resolution active-matrix organic, and inorganic light-emitting diodes displays.