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 similar 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. (C) 2011 American Institute of Physics. [doi:10.1063/1.3657511]