Electrical characteristics of Al-doped ZnO-channel thin-film transistor with high-κ HfON/SiO2 stack gate dielectric

Al-doped ZnO (AZO) thin film was deposited by radio-frequency reactive sputtering under different Ar/O
₂
ratios, and its electrical properties were investigated. The AZO film with relatively low carrier concentration and high Hall mobility was used as the active channel, and bottom-gate top-contact AZO TFTs with high-κ HfON/SiO
₂
stack gate dielectric were fabricated. The AZO TFT (W/L = 500/40 μm) showed electrical characteristics with a drain current of 1.9 μA, a saturation mobility of 1.66 cm
²
/Vs, a threshold voltage of 2.1 V, a subthreshold swing of 2.7 V/dec, and an on/off current ratio of 5×10
²
. Also, the saturation mobility of the AZO TFT with HfON/SiO
₂
stacked gate dielectric has been improved by one order of magnitude compared to previous work.