O-vacancy as the origin of negative bias illumination stress instability in amorphous In-Ga-Zn-O thin film transistors

We find that O-vacancy (V(O)) acts as a hole trap and plays a role in negative bias illumination stress instability in amorphous In-Ga-Zn-O thin film transistors. Photoexcited holes drift toward the channel/dielectric interface due to small potential barriers and can be captured by V(O) in the dielectrics. While some of V(O)(+2) defects are very stable at room temperature, their original deep states are recovered via electron capture upon annealing. We also find that V(O)(+2) can diffuse in amorphous phase, inducing hole accumulation near the interface under negative gate bias. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3464964]