Improved electrical performance and stability of top-gated indium–tin–zinc–oxide thin-film transistors via oxygen plasma treatment

Abstract This study investigates the improvement of the electrical characteristics and bias-stress stability of top-gated indium–tin–zinc–oxide (ITZO) thin-film transistors (TFTs) via oxygen (O 2 ) plasma treatment. The O 2 plasma process is selectively applied to the channel region overlapping the source/drain electrodes to modulate its electronic and chemical properties. X-ray photoelectron spectroscopy analysis reveals that the observed performance improvements are attributed to an increased metal oxide concentration, along with a reduction in oxygen vacancy and hydroxyl concentrations in the channel region following O 2 plasma treatment. These chemical modifications facilitate improved carrier mobility, suppression of bulk trap density, and reduction of the source/drain contact resistance in ITZO TFTs. As a result, the O 2 plasma-treated devices exhibit excellent electrical performance, with a saturation mobility ( µ sat ) of 19.19 ± 2.15 cm 2 /Vs, a threshold voltage ( V TH ) of 0.57 ± 0.04 V, a subthreshold swing (SS) of 87.7 ± 4.7 mV/dec, and an on/off current ratio exceeding 10 8 . Compared to untreated devices, the O 2 plasma treatment yields ∼50% higher µ sat and ∼6% lower SS. Furthermore, O 2 plasma treatment markedly enhances device stability under negative bias stress and negative bias temperature stress, with substantially reduced V TH shifts relative to untreated counterparts.