Transparent and flexible oxide thin-film-transistors using an aluminum oxide gate insulator grown at low temperature by atomic layer deposition

Al₂O₃ dielectric layers with a dense and atomically flat surface were grown at relatively low temperatures of 150 C by atomic layer deposition (ALD) for use as the gate oxide of transparent and flexible oxide thin-film-transistors (TFTs). The ALD growth of the high quality Al ₂O₃ with a less rough surface at 120 C allowed us to use the liftoff process without wet chemical etching and made the fabrication method for flexible electronics simple. This also improved the electrical performance of the oxide TFTs, such as high field effect mobility, low subthreshold gate swing, and low hysteresis behavior, due to the low charge trap sites at the gate oxide and channel interface. Finally, we fabricated InGaZnO TFTs with good device performance on a flexible substrate with poly-4-vinylphenol coating at a maximum processing temperature of 120 C.