Potential solution-induced HfAlO dielectrics and their applications in low-voltage-operating transistors and...

Recently, much attention has been paid to the investigation of solution-driven oxides for application in thin film transistors (TFTs). In current study, a fully solution-based method, using 2-methoxyethanol as solvent, has been adopted to prepare InZnO thin films and HfAlO gate dielectrics. Amorphous HfAlO thin films annealed at 600 °C have shown a high transparency (>85%), low leakage current density (6.9 × 10^-9 A cm^-2 at 2 MV cm^-1), and smooth surface. To verify the potential applications of HfAlO gate dielectrics in oxide-based TFTs, fully solution-induced InZnO/HfAlO TFTs have been integrated. Excellent electrical performance for InZnO/HfAlO TFTs annealed at 450 °C has been observed, including a low operating voltage of 3 V, a saturated mobility of 5.17 cm² V^-1 s^-1, a high I _on/I _off of ∼10⁶, a small subthreshold swing of 87 mV per decade, and a threshold voltage shift of 0.52 V under positive bias stress (PBS) for 7200 s, respectively. In addition, time dependent threshold voltage shift under PBS could be described by a stretched-exponential model, which can be due to charge trapping in the semiconductor/dielectric interface. Finally, to explore the possible application in logic operation, a resistor-loaded inverter based on InZnO/HfAlO TFTs has been built and excellent swing characteristic and well dynamic behavior have been obtained. Therefore, it can be concluded that fully solution-driven InZnO/HfAlO TFTs have demonstrated potential application in nontoxic, eco-friendly and low-power consumption oxide-based flexible electronics.