Highly Robust Spray-Pyrolyzed Al₂O₃ Gate Insulator for Flexible a-IGZO Thin-Film Transistors for Low-Power Displays

초록

Thin-film transistor (TFT) is a key element in flexible display technology for energy-efficient wearable electronics. A systematic analysis is performed to demonstrate the high-quality high-k Al2O3 gate insulator (GI) by low-cost spray pyrolysis on a polyimide (PI) substrate for low-power flexible displays. The spray-pyrolyzed Al2O3 film deposited at 375 degrees C shows an amorphous phase, smooth surface roughness, and higher metal-oxygen bonding states. Additionally, one-cycle Ar/O-2 plasma treatment on Al2O3 enhances the dielectric properties, exhibiting a lower leakage current density of 6.1 x 10(-6) A cm(-2) (@6.0 MV cm(-1)), higher breakdown electric field of 9.7 MV cm(-1), and negligible frequency dependence in capacitance curves. The high-performance and robust amorphous InGaZnO TFTs are fabricated using Al2O3 GI on a PI substrate, demonstrating a field-effect mobility of 13.4 cm(2) V-1 s(-1), threshold voltage of -0.7 V, subthreshold swing of 0.305 V dec(-1), I-ON/I-OFF ratio of approximate to 10(9), gate leakage current of approximate to 0.1 pA, zero hysteresis voltage, and stable operation against electrical and mechanical stresses. Finally, a high-speed ring oscillator operating at an oscillation frequency of 2.63 MHz, along with a gate driver exhibiting rising and falling times of 655 and 576 ns, are presented using spray-pyrolyzed Al2O3/a-IGZO TFTs on a PI substrate.

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