Improved performance of InGaZnO thin-film transistors with Ta2O5/Al2O3 stack deposited using pulsed laser deposition

• IGZO TFT with Ta2O5/Al2O3 dielectrics is successfully fabricated by PLD.
• The Ta2O5/Al2O3 dielectric stacks show low leakage current and large capacitance.
• IGZO TFT with Ta2O5/Al2O3 dielectrics shows good performance.
• The small SS is comparable with that of submicrometer single-crystalline Si MOSFET.

Ta2O5/Al2O3 stacked thin film was fabricated as the gate dielectric for low-voltage-driven amorphous indium–gallium–zinc-oxide (IGZO) thin film transistors (TFTs). The Ta2O5/Al2O3 stacked thin film exhibits a combination of the advantages of Al2O3 and Ta2O5. The IGZO TFT with Ta2O5/Al2O3 stack exhibits good performance with large saturation mobility of 26.66 cm2 V−1 s−1, high on/off current ratio of 8 × 107, and an ultra-small subthreshold swing (SS) of 78 mV/decade. Such small SS value is even comparable with that of submicrometer single-crystalline Si MOSFET.