Effect of oxygen vacancy control on the electrical performance and stability of amorphous Si-In-Zn-O thin-film transistors by adopting Ar plasma treatment

초록

The effects of Ar plasma treatment on the electrical performance and the stability of amorphous Si-In-Zn-O (a-SIZO) thin-film transistors (TFTs) were investigated with a focus on oxygen vacancy (VO) modulation. Short plasma exposure (<= 30 s) improved the field-effect mobility (& micro;FE) from 14.5 to 15.8 cm2/V & centerdot;s while maintaining stable subthreshold swing (S.S.) and threshold voltage (VTH). In contrast, prolonged plasma exposure (>= 1 min) resulted in a VTH shift from 8.70 V to 3.49 V and degradation of S.S. from 0.481 to 0.813 V/decade, along with significant increases in hysteresis (1.60 -> 6.76 V) and Delta VTH (1.17 -> 12.06 V). X-ray photoelectron spectroscopy (XPS) analysis revealed that the VO concentration increased from 26.28% to 36.03% (1 min treated) with increasing plasma treatment time, originating from Ar ion-induced M-O bond breaking. A moderate increase in VO enhances carrier transport, whereas excessive VO generation induces trap states. Density of state (DoS) analysis confirmed that trap density increased with plasma exposure, showing a quantitative correlation with VO concentration, where bulk traps (DoS, NT) and interface traps (hysteresis) were distinguished. These results demonstrate that Ar plasma treatment induces a trade-off between electrical performance and stability through VO-controlled defect formation, highlighting the importance of precise plasma condition optimization.

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