High-Performance a-IGZO Thin-Film Transistor Using Ta2O5 Gate Dielectric

Abstract —In this letter, we report the fabrication of an amor-phous indium gallium zinc oxide (a-IGZO) thin-film transistorwith a high- k dielectric layer on a glass substrate. The room-temperature-deposited a-IGZO channel with Ta 2 O 5 exhibits thefollowing operating characteristics: a threshold voltage of 0.25 V,a drain–source current on/off ratio of 10 5 , a subthreshold gatevoltage swing of 0.61 V/decade, and a high field-effect mobility of61.5 cm 2 / V · s; these characteristics make it suitable for use as aswitching transistor and in low-power applications. IndexTerms —Amorphous indium gallium zinc oxide (a-IGZO),high- k ,Ta 2 O 5 , thin-film transistor (TFT). I. I NTRODUCTION R ECENTLY, studies on transparent oxide thin-film tran-sistors (TFTs) have attracted considerable attention withrespect to display applications because of the high mobilityand high aspect ratio of these transistors. Nomura et al. [1]reported the fabrication of a transparent TFT using amorphousindium gallium zinc oxide (a-IGZO) as the channel layer anda high-