PUB-2016-EZT

Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics

Fwzah H. Alshammari, Pradipta K. Nayak, Zhenwei Wang, and Husam N. Alshareef, "Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics"
​ACS Appl. Mater. Interfaces, 2016, 8 (35), pp 22751–22755
Fwzah H. Alshammari, Pradipta K. Nayak, Zhenwei Wang, and Husam N. Alshareef
aluminum oxide; bilayer; tantalum oxide; thin film transistor; zinc oxide
2016
​We report ZnO TFTs using Al2O3/Ta2O5 bilayer gate dielectrics grown by atomic layer deposition. The saturation mobility of single layer Ta2O5 dielectric TFT was 0.1 cm2 V–1 s–1, but increased to 13.3 cm2 V–1 s–1 using Al2O3/Ta2O5 bilayer dielectric with significantly lower leakage current and hysteresis. We show that point defects present in ZnO film, particularly VZn, are the main reason for the poor TFT performance with single layer dielectric, although interfacial roughness scattering effects cannot be ruled out. Our approach combines the high dielectric constant of Ta2O5 and the excellent Al2O3/ZnO interface quality, resulting in improved device performance.​​​