High performance thin film transistors with cosputtered amorphous indium gallium zinc oxide channel

The authors report the fabrication of high performance thin film transistors (TFTs) with an amorphous indium gallium zinc oxide (a-IGZO) channel, which was deposited by cosputtering using a dual IGZO and indium zinc oxide (IZO) target. The effect of the indium content on the device performance of the a-IGZO TFTs was investigated. At a relatively low IZO power of 400 W, the field-effect mobility (mu(FE)) and subthreshold gate swing (S) of the a-IGZO TFTs were dramatically improved to 19.3 cm(2)/V s and 0.35 V/decade, respectively, compared to those (11.2 cm(2)/V s and 1.11 V/decade) for the TFTs with the a-IGZO channel (reference sample) prepared using only the IGZO target. The enhancement in the subthreshold I-DS-V-GS characteristics at an IZO power of 400 W compared to those of the reference sample was attributed to the reduction of the interface trap density rather than the reduction of the bulk defects of the a-IGZO channel.