Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment

The effect of Ar plasma treatment on amorphous indium gallium zinc oxide ( a -IGZO) thin films was investigated. The net electron carrier concentration ( 10 20 - 10 21 cm − 3 ) of the a -IGZO thin films dramatically increased upon their exposure to the Ar plasma compared to that ( 10 14 cm − 3 ) of the as-deposited thin film. The authors attempted to reduce the contact resistance between the Pt ∕ Ti (source/drain electrode) and a -IGZO (channel) by using the Ar plasma treatment. Without the treatment, the a -IGZO thin film transistors (TFTs) with W ∕ L = 50 ∕ 4 μ m exhibited a moderate field-effect mobility ( μ FE ) of 3.3 cm 2 ∕ V s , subthreshold gate swing ( S ) of 0.25 V ∕ decade , and I on ∕ off ratio of 4 × 10 7 . The device performance of the a -IGZO TFTs was significantly improved by the Ar plasma treatment. As a result, an excellent S value of 0.19 V ∕ decade and high I on ∕ off ratio of 1 × 10 8 , as well as a high μ FE of 9.1 cm 2 ∕ V s , were achieved for the treated a -IGZO TFTs.