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

We investigate the effect of channel layer thickness on effective mobility ( $\mu _{\text {eff}}$ ) in the sub-10-nm regime of amorphous indium–gallium–zinc–oxide thin-film transistors ( $\alpha $ -IGZO TFTs). TFT devices with extremely scaled channel thickness ${t} _{{\alpha}-{\text {IGZO}}}$ of 3.6 nm were realized, exhibiting low subthreshold swing (SS) of 74.4 mV/decade and the highest effective mobility $\mu _{\text {eff}}$ of 34 cm2/ $V\cdot s $ at a carrier density ${N} _{Carrier}$ of $\sim 5 \times 10^{12}$ cm−2 for any kind of $\alpha $ -IGZO TFTs having sub-10-nm ${t} _{{\alpha}-{\text {IGZO}}}$ . No significant degradation of $\mu _{\text {eff}}$ is observed as $\alpha $ -IGZO thickness reduced from 6 to 3.6 nm. By scaling down the channel length ${L} _{\text {CH}}$ to 38 nm, high extrinsic transconductance ( ${G} _{m, \max}$ ) of $125~\mu \text{s}/\mu \text{m}$ (at ${V}_{\text {DS}}$ of 1 V) and ON-state current ${I} _{\text {ON}}$ of $350~\mu \text{A}/\mu \text{m}$ at ${V}_{\text {GS}}$ – ${V} _{T}$ of 3 V with ${V}_{\text {DS}}$ of 2.5 V are achieved.