Effects of Deposition Power and Annealing Temperature on Indium Zinc Oxide (IZO) Film’s Properties and Their Applications to the Source–Drain Electrodes of Amorphous Indium Gallium Zinc Oxide (a-IGZO) Thin-Film Transistors (TFTs)

The optical, electrical, and material properties of In-Zn-O (IZO) films were optimized by adjusting the deposition power and annealing temperature. Films deposited at 125 W and annealed at 300 °C exhibited the best performance, with the lowest resistivity (1.43 × 10^-3 Ω·cm), highest mobility (11.12 cm²/V·s), and highest carrier concentration (4.61 × 10²⁰ cm^-3). The average transmittance and optical energy gap were 82.57% and 3.372 eV, respectively. The electrical characteristics of amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) using IZO source-drain (S-D) electrodes with various sputtering powers and annealing temperatures were investigated. The optimal sputtering power of 125 W and annealing temperature of 300 °C for the IZO S-D electrodes resulted in the highest field-effect mobility (~12.31 cm²/V·s) and on current (~2.09 × 10^-6 A). This improvement is attributed to enhanced carrier concentration and mobility, which result from the high In/Zn ratio, the larger grain size, and low RMS roughness in the IZO films. The parasitic contact resistance (<i>R_SD</i>) and channel resistance (<i>R_CH</i>) were analyzed using the total resistance method. <i>R_SD</i> decreased with increasing IZO S-D sputtering power, while <i>R_CH</i> reached a minimum at 125 W. Both resistances decreased significantly as the annealing temperature increased from 200 °C to 300 °C.