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 (1020–1021cm−3) of the a-IGZO thin films dramatically increased upon their exposure to the Ar plasma compared to that (1014cm−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∕4μm exhibited a moderate field-effect mobility (μFE) of 3.3cm2∕Vs, subthreshold gate swing (S) of 0.25V∕decade, and Ion∕off ratio of 4×107. The device performance of the a-IGZO TFTs was significantly improved by the Ar plasma treatment. As a result, an excellent S value of 0.19V∕decade and high Ion∕off ratio of 1×108, as well as a high μFE of 9.1cm2∕Vs, were achieved for the treated a-IGZO TFTs.