Origin of instability by positive bias stress in amorphous Si-In-Zn-O thin film transistor

The origin of instability under positive bias stress (PBS) in amorphous Si-In-Zn-O (SIZO) thin film transistor (TFT) with different Si concentration has been investigated by x-ray photoelectron spectroscopy (XPS) and density of states (DOSs) analysis. It is found that stability of SIZO-TFT with 3 wt. % Si under PBS became more deteriorated than that of 1 wt. % Si incorporated SIZO-TFT due to the increased oxygen related trap distributed in energy range from conduction band to ∼0.3 eV below the conduction band. The origin of instability under PBS was discussed in terms of oxygen related trap derived from DOSs and XPS analysis.