A 2D Empirical Model for On-State Operation of Scaled IGZO TFTs Exemplifying the Physical Response of TCAD Simulation

Abstract

A device model developed for the on-state operation of accumulation-mode IGZO TFTs is presented as an adaptation of a Level 2 SPICE (L2S) model. The model accounts for the ionization and deionization of acceptor-like band-tail states (BTS), as controlled by both the gate and drain bias conditions. ID - VDS output characteristics are well represented by the device model which includes the physical channel length and width, gate dielectric thickness, and seven operational parameters. Along with selected traditional L2S parameters, the introduced BTS parameters accurately reflect the level of free electron charge and associated current in triode and saturation modes. Model parameters were extracted using regression analysis on output characteristics with fine gate voltage increments. The device model accurately represents long-channel and scaled devices with bottom-gate and double-gate electrode configurations. The physical correlation of the model to device operation is demonstrated through comparisons with measured characteristics and TCAD simulation.