High-Performance a-InGaZnO Thin-Film Transistors with Extremely Low Thermal Budget by Using a Hydrogen-Rich Al2O3 Dielectric

Electrical characteristics of amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) are compared by using O 2 plasma-enhanced atomic layer deposition Al 2 O 3 dielectrics at different temperatures. High-performance a-IGZO TFTs are demonstrated successfully with an Al 2 O 3 dielectric deposited at room temperature, which exhibit a high field-effect mobility of 19.5 cm 2 V − 1 s − 1 , a small subthreshold swing of 160 mV/dec, a low threshold voltage of 0.1 V, a large on/off current ratio of 4.5 × 10 8 , and superior negative and positive gate bias stabilities. This is attributed to the hydrogen-rich Al 2 O 3 dielectric deposited at room temperature in comparison with higher deposition temperatures, thus efficiently passivating the interfacial states of a-IGZO/Al 2 O 3 and the oxygen vacancies and improving conductivity of the a-IGZO channel by generating additional electrons because of enhanced hydrogen doping during sputtering of IGZO. Such an extremely low thermal budget for high-performance a-IGZO TFTs is very attractive for flexible electronic application.