Impact of Applied Voltage on Threshold Voltage Instability in Active Load Thin-Film a-IGZO Inverters

This work presents an analysis and modeling of the electrical stress effects caused by different voltages on a logic inverter device circuit based on thin-film transistor (TFT) technology. The study includes the characterization of single indium-gallium-zinc oxide (IGZO) TFTs and inverters with an active load configuration to investigate the behavior of their threshold voltage (
${V}_{\text {TH}}{)}$
under various bias voltages. Additionally, an analytical model is used to quantify the impact of electrical stress on the trapping parameters of the dielectric–semiconductor interface. The model demonstrates that the charged trapped concentration increases exponentially with the applied voltage bias, resulting in a significant initial shift in
${V}_{\text {TH}}$
. Importantly, this analytical model allows the assessment of the electrical stress effect on TFT-based circuits. The findings can inform the determination of a maximum applied voltage bias based on the desired threshold voltage. Furthermore, the model facilitates the estimation of circuit reliability and lifetime by considering the polarization time under different applied voltage bias conditions.