Role of oxygen interstitials in drain current drop effect of a-InGaZnO thin-film transistors

Amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) would exhibit significant drain current drop (DCD) degradation at high drain voltage, which has been ascribed to the impact of hot carriers on the lattice of a-IGZO films. This study unveils that interstitial oxygen (O_i) defects also contribute to DCD degradation. It is inferred that the weak interstitial oxygen bonds near the drain region would be easily broken by the impact of hot carriers. Thus, the acceptor-like interstitial oxygen trap states are generated, leading to the aggravated deterioration of DCD. In addition, it is observed that the introduction of hydrogens effectively alleviates the DCD degradation, which is attributed to hydrogen-induced transitions from the weak interstitial oxygen bonds to the strong oxygen−hydrogen bonds.