Impact of Sputtering Power on Amorphous In–Al–Zn–O Films and Thin Film Transistors Prepared by RF Magnetron Sputtering

High-performance In-Al-Zn-O (IAZO) films and thin film transistors (TFTs) were fabricated using RF magnetron sputtering. The influence of sputtering power (90-250 W) on the film properties and device performance was investigated. All the IAZO films were in the amorphous state both before and after annealing, with a decrease in surface roughness observed with the increase of sputtering power. The Hall mobility of the annealed IAZO films degraded as the sputtering power increased. The highest Hall mobility of 63.6 cm
²
/V·s and a proper carrier concentration of 3.22 × 10
¹⁴
/cm
³
were obtained for the 90-W-deposited film. All the IAZO films exhibited high average visible transmittances (above 92%) and large optical bandgaps (4.10 ± 0.03 eV). The IAZO TFT prepared at 90 W had the best electrical properties with a high saturation mobility of 12.08 cm
²
/V·s, a high ON-OFF current ratio of 7.75×10
⁷
, a low hysterisisof -0.19V, and a low subthreshold swing (SS) of 0.55 V/dec.