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

TL;DR

This study reveals that oxygen vacancies in amorphous In-Ga-Zn-O thin film transistors cause negative bias illumination stress instability by trapping holes, diffusing, and being recoverable through annealing, affecting device stability.

Contribution

It demonstrates that oxygen vacancies act as hole traps and influence bias stress instability, highlighting their role in device degradation mechanisms.

Findings

O-vacancies trap holes and contribute to instability.

Vo(+2) defects are stable but recoverable via annealing.

Vo(+2) can diffuse and cause hole accumulation near interfaces.

Abstract

We find that O-vacancy (Vo) acts as a hole trap and play a role in negative bias illumination stress instability in amorphous In-Ga-Zn-O thin film transistors. Photo-excited holes drifted toward the channel/dielectric interface due to small potential barriers and can be captured by Vo in the dielectrics. While Vo(+2) defects are very stable at room temperature, their original deep states are recovered via electron capture upon annealing. We also find that Vo(+2) can diffuse in amorphous phase, including hole accumulation near the interface under negative gate bias.