The Impact of Passivation Layers on the Negative Bias Temperature Illumination Instability of Ha-In-Zn-O TFT

Abstract

We systematically investigated the role of the and/or passivation layer in the amorphous hafnium indium zinc oxide (HIZO) thin film transistors (TFTs) under a negative bias temperature illumination stress (NBTIS) condition. The device instability of the TFTs with a passivation layer [threshold voltage shift ] is better than that of the TFTs with a passivation layer in the atmosphere. However, the devices with the passivation layer showed different instabilities in the atmosphere and ambient . The film analysis demonstrated the higher water permeability of the film and higher hydrogen content of the films, suggesting the existence of not only water related positive charge traps but also hydrogen related positive charge traps under NBTIS conditions. After including the (inner)/ (outer) passivation layers, the instability of the amorphous HIZO device was drastically improved by the suppression of the positive charge trapping sites under the NBTIS conditions.