High-performance amorphous gallium indium zinc oxide thin-film transistors through N2O plasma passivation

Abstract

Amorphous-gallium-indium-zinc-oxide ($a$ -GIZO) thin filmtransistors (TFTs) are fabricated without annealing, using processes and equipment for conventional $a\text{-}\mathrm{Si}:\mathrm{H}$ TFTs. It has been very difficult to obtain sound TFT characteristics, because the $a$ -GIZO active layer becomes conductive after dry etching the Mo source/drain electrode and depositing the $a\text{-}\mathrm{Si}{\mathrm{O}}_2$ passivation layer. To prevent such damages, ${\mathrm{N}}_2\mathrm{O}$ plasma is applied to the back surface of the $a$ -GIZO channel layer before $a\text{-}\mathrm{Si}{\mathrm{O}}_2$ deposition. ${\mathrm{N}}_2\mathrm{O}$ plasma-treated $a$ -GIZO TFTs exhibit excellent electrical properties: a field effect mobility of $37{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ , a threshold voltage of $0.1\mathrm{V}$ , a subthreshold swing of $0.25\mathrm{V}$ /decade, and an $I_{\text{on}∕\text{off}}$ ratio of 7.