Amorphous InGaZnO Thin-Film Transistors—Part II: Modeling and Simulation of Negative Bias Illumination Stress-Induced Instability

Abstract

Based on the physical model of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) and the extracted density of states described in Part I, a quantitative investigation of mechanisms on the negative bias illumination stress (NBIS)-induced threshold voltage <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VT</i> instability of a-IGZO TFTs is presented. It is found that the shallow donor state-creation model explains the NBIS time evolution of the electrical characteristics very well. Furthermore, the semi-empirical rule of the NBIS-induced Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> is proposed and demonstrated based on the shallow donor state-creation model. The proposed approach can be used to optimize the fabrication process and to explore high-performance thin-film materials for mass-production-level amorphous oxide semiconductor TFTs to be innovatively used in the near future.