Two-stage unified stretched-exponential model for time-dependence of threshold voltage shift under positive-bias-stresses in amorphous indium–gallium–zinc oxide thin-film transistors

Abstract

In this study, we show that the two-stage unified stretched-exponential model can more exactly describe the time-dependence of threshold voltage shift (ΔVTH) under long-term positive-bias-stresses compared to the traditional stretched-exponential model in amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs). ΔVTH is mainly dominated by electron trapping at short stress times, and the contribution of trap state generation becomes significant with an increase in the stress time. The two-stage unified stretched-exponential model can provide useful information not only for evaluating the long-term electrical stability and lifetime of the a-IGZO TFT but also for understanding the stress-induced degradation mechanism in a-IGZO TFTs.