Despite　intensive　research　on　improvement　in　electrical　performances　of　ZnO-based　thin-film　transistors　(TFTs),　the　instability　issues　have　limited　their　applications　for　complementary　electronics.　Herein,　we　have　investigated　the　effect　of　nitrogen　and　hydrogen　(N/H)　codoping　on　the　electrical　performance　and　reliability　of　amorphous　InGaZnO　(α-IGZO)　TFTs.　The　performance　and　bias　stress　stability　of　α-IGZO　device　were　simultaneously　improved　by　N/H　plasma　treatment　with　a　high　field-effect　mobility　of　45.3　cm2/(V　s)　and　small　shifts　of　threshold　voltage　(Vth).　On　the　basis　of　X-ray　photoelectron　spectroscopy　analysis,　the　improved　electrical　performances　of　α-IGZO　TFT　should　be　attributed　to　the　appropriate　amount　of　N/H　codoping,　which　could　not　only　control　the　Vth　and　carrier　concentration　efficiently,　but　also　passivate　the　defects　such　as　oxygen　vacancy　due　to　the　formation　of　stable　Zn　-　N　and　N　-　H　bonds.　Meanwhile,　low-frequency　noise　analysis　indicates　that　the　average　trap　density　near　the　α-IGZO/SiO2　interface　is　reduced　by　the　nitrogen　and　hydrogen　plasma　treatment.　This　method　could　provide　a　step　toward　the　development　of　α-IGZO　TFTs　for　potential　applications　in　next-generation　high-definition　optoelectronic　displays.　©　2017　American　Chemical　Society.