Extraction of Propagation Delay-Correlated Mobility and Its Verification for Amorphous InGaZnO Thin-Film Transistor-Based Inverters

We found that field-effect mobility, which had been widely used in the evaluation of the mobility of an amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) failed to describe the effect of mobility on propagation delay (tPD) in an a-IGZO TFT-based circuit, and also proposed an extraction technique for the tPD-correlated mobility (μ_tPD) considering both the subgap density-of-states and the voltage-dependent charge density. It is verified that the proposed μ_tPD is the best correlated with the measured tPD in IGZO TFT-based inverters other than various mobilities in the literature. Our results have revealed that it is possible to predict tPD only with the measured current-voltage characteristic of the a-IGZO TFT without measuring tPD in IGZO-based circuits.