Analytical Drain Current and Capacitance Model for Amorphous InGaZnO TFTs Considering Temperature Characteristics

Analytical drain current and capacitance model is developed for the amorphous InGaZnO (a-IGZO) thin-film transistor (TFT). The numerical Pao-Sah model is presented to describe the temperature characteristics considering the deep and tail trap states in the energy gap of the a-IGZO thin film. The numerical model is successful for the TFT in both the subthreshold regime and the above-threshold regime. In the subthreshold regime, considering that the trapped electron concentration in the deep trap states dominates the Poisson's equation, the surface-potential-based analytical model is presented. In the above-threshold regime, the threshold-voltage-based analytical model is presented. Applying the smooth function to connect the subthreshold model and the above-threshold model, the analytical compact model is obtained. The compact model is verified by the numerical Pao-Sah model and the available experimental data from 253 to 393 K. Furthermore, the temperature characteristics of the field-effect mobility are discussed.