Amorphous InGaZnO Thin-Film Transistors With Sub-10-nm Channel Thickness and Ultrascaled Channel Length

Abstract

We investigate the effect of channel layer thickness on effective mobility (μeff) in the sub-10-nm regime of amorphous indium-gallium-zinc-oxide thin-film transistors (α-IGZO TFTs). TFT devices with extremely scaled channel thickness tα-IGZO of 3.6 nm were realized, exhibiting low subthreshold swing (SS) of 74.4 mV/decade and the highest effective mobility μeff of 34 cm2/V·s at a carrier density NCarrier of ~5×1012 cm-2 for any kind of α-IGZO TFTs having sub-10-nm tα-IGZO. No significant degradation of μeff is observed as α-IGZO thickness reduced from 6 to 3.6 nm. By scaling down the channel length LCH to 38 nm, high extrinsic transconductance (Gm,max) of 125 μs/μm (at VDS of 1 V) and ON-state current ION of 350 μA/μm at VGS-VT of 3 V with VDS of 2.5 V are achieved.