Sol‐gel derived TiNb2O7 dielectric thin films for transparent electronic applications

To reduce power consumption of transparent oxide‐semiconductor thin film transistors, a gate dielectric material with high dielectric constant and low leakage current density is favorable. According to previous study, the bulk TiNb₂O₇ with outstanding dielectric properties may have an interest in its thin‐film form. The optical, chemical states and surface morphology of sol‐gel derived TiNb₂O₇ (TNO) thin films are investigated the effect of postannealing temperature lower than 500°C, which is crucial to the glass transition temperature. All films possess a transmittance near 80% in the visible region. The existence of non‐lattice oxygen in the TNO film is proposed. The peak area ratio of non‐lattice oxygen plays an important role in the control of leakage current density of MIM capacitors. Also, the capacitance density and dissipation factor were affected by the indium tin oxide (ITO) sheet resistance at high frequencies. The sample after postannealing at 300°C and electrode‐annealing at 150°C possesses a high dielectric constant (>30 at 1 MHz) and a low leakage current density (<1 × 10^?6 A/cm² at 1 V), which makes it a very promising gate dielectric material for transparent oxide‐semiconductor thin film transistors.