The effects of oxygen annealing on the electrical characteristics of hydrothermally grown zinc oxide thin-film transistors

High-performance transparent zinc oxide (ZnO) thin-film transistors (TFTs) with location-controlled lateral-grain growth were fabricated by hydrothermal method. The ZnO active channel was laterally grown with aluminum-doped ZnO (AZO) seed layer underneath the Ti/Pt film. Compare to the unannealed ZnO TFTs, the annealed devices reveal the high-quality ZnO layer with the compensated structural defects in the channel region after oxygen ambient annealing at 400 °C. Therefore, the superior device performances (i.e. the excellent filed-effect mobility of 9.07 cm2/V s, positive threshold voltage of 2.25 V, high on/off current ratio of ∼106, and low gate leakage current of <1 nA) of hydrothermally grown ZnO TFTs can be achieved with oxygen ambient annealing.

► Hydrothermally grown (HTG) transparent ZnO TFTs were fabricated on glass substrates.
► ZnO active layer was laterally grown with AZO seed layer underneath the Ti/Pt film.
► Only single grain boundary was found vertically to the channel direction of ZnO TFTs.
► O2 annealed TFTs reveal the compensated structural defects in ZnO active layer.
► The superior device performances of HTG ZnO TFTs can be achieved with O2 annealing.