Effects of e-beam deposited gate dielectric layers with atmospheric pressure plasma treatment for IGZO thin-film transistors

In this report, indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) performances were improved using atmospheric pressure plasma treatment on e-beam deposited silicon dioxide gate dielectric layers. The impact on the electrical properties of the IGZO-TFTs with different plasma powers at fixed N₂ gas flow rate on the SiO₂ dielectric surface has been investigated. The performances of the IGZO TFTs showed improvement at high power of 300 W and 400 W treatments. The amorphous IGZO films on SiO₂/ITO glass achieved transmittance higher than 90% in the wavelength range of 350–1000 nm, and it could be further enhanced with increasing plasma treatment power. The reduced surface roughness in the SiO₂ gate dielectric layer from increased plasma power would affect the performance of IGZO TFTs, especially by higher current on/off ratio, enhanced electron mobility, reduced sub-threshold swing voltage and interfacial trap charge density, and decreased threshold voltage. The amorphous IGZO TFTs with plasma treatment power at 400 W exhibited the field effect mobility, sub-threshold swing, on-current to off-current ratio, interfacial trap density and threshold voltage of 33.5 cm²/V s, 0.10 V/dec, 10⁷, 1.2 × 10¹² cm^− 2 eV^− 1 and 0.77 V, respectively. In addition, the high mobility of 33.5 cm²/V s was achieved using simple and cost-effective atmospheric pressure plasma treatment on e-beam deposited SiO₂ gate dielectrics.