Effects of argon flow rate on electrical properties of amorphous indium gallium zinc oxide thin-film transistors

In this report, amorphous indium gallium zinc oxide (a-IGZO) thin films were deposited on glass substrates using different argon flow rates (AFRs). The impact on the electrical properties of the a-IGZO thin-film transistors with various AFRs during film growth has been carefully investigated. The AFR varied 20-60 sccm while the oxygen flow rate was maintained at 1 sccm. All a-IGZO films achieved transmittance higher than 80% in the wavelength range of 350-1000 nm, and it increased slightly with increasing AFR in the higher wavelength region. The rise in partial pressure due to increased AFR could affect the performance, in particular by increasing the current on/off ratio, and changes in electron mobility, sub-threshold swing voltage and threshold voltage. The optimal results were attained at AFR of 50 sccm. The field effect mobility, sub-threshold swing, ratio of on-current to the off-current, interfacial trap density and threshold voltage are 27.7 cm²/V·s, 0.11 V/dec, 2.9 × 10⁸, 1.1 × 10¹² cm^{- 2} eV^{- 1} and 0.84 V, respectively. In addition, good electrical properties were achieved using dielectric SiO₂ prepared by simple, low-cost electron beam evaporator system.