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

초록

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 (O2) plasma treatment. The O2 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 O2 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 O2 plasma-treated devices exhibit excellent electrical performance, with a saturation mobility (mu sat) of 19.19 +/- 2.15 cm2/Vs, a threshold voltage (VTH) of 0.57 +/- 0.04 V, a subthreshold swing (SS) of 87.7 +/- 4.7 mV/dec, and an on/off current ratio exceeding 108. Compared to untreated devices, the O2 plasma treatment yields similar to 50% higher mu sat and similar to 6% lower SS. Furthermore, O2 plasma treatment markedly enhances device stability under negative bias stress and negative bias temperature stress, with substantially reduced VTH shifts relative to untreated counterparts.

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