Tailoring IGZO composition for enhanced fully solution-based thin film transistors

Solution-processed metal oxides have been investigated as an alternative to vacuum-based oxides to implement low-cost, high-performance electronic devices on flexible transparent substrates. However, their electrical properties need to be enhanced to apply at industrial scale. Amorphous indium-gallium-zinc oxide (a-IGZO) is the most-used transparent semiconductor metal oxide as an active channel layer in thin-film transistors (TFTs), due to its superior electrical properties. The present work evaluates the influence of composition, thickness and ageing on the electrical properties of solution a-IGZO TFTs, using solution combustion synthesis method, with urea as fuel. After optimizing the semiconductor properties, low-voltage TFTs were obtained by implementing a back-surface passivated 3-layer In:Ga:Zn 3:1:1 with a solution-processed high-k dielectric; AlO_x. The devices show saturation mobility of 3.2 cm² V^-1 s^-1, IOn/IOff of 10⁶, SS of 73 mV dec-1 and VO_n of 0.18 V, thus demonstrating promising features for low-cost circuit applications.