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 (
${t}_{\rm PD}$
) in an a-IGZO TFT-based circuit, and also proposed an extraction technique for the
${t}_{\rm PD}$
-correlated mobility (
$\mu _{{{t_{\rm PD}}}}$
) considering both the subgap density-of-states and the voltage-dependent charge density. It is verified that the proposed
$\mu _{{{t_{\rm PD}}}}$
is the best correlated with the measured
${t}_{\rm PD}$
in IGZO TFT-based inverters other than various mobilities in the literature. Our results have revealed that it is possible to predict
${t}_{\rm PD}$
only with the measured current–voltage characteristic of the a-IGZO TFT without measuring
${t}_{\rm PD}$
in IGZO-based circuits.