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 mu m exhibited a moderate field-effect mobility (mu(FE)) of 3.3 cm(2)/V s, subthreshold gate swing (S) of 0.25 V/decade, and I-on/off ratio of 4 x 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 x 10(8), as well as a high mu(FE) of 9.1 cm(2)/V s, were achieved for the treated a-IGZO TFTs. (c) 2007 American Institute of Physics.