A threshold voltage and drain current model for symmetric dual-gate amorphous In GaZnO thin film transistors  

作　　者：Minxi CAI Ruohe YAO 

机构地区：[1]School of Electronic and Information Engineering, South China University of Technology

出　　处：《Science China(Information Sciences)》2018年第2期190-199,共10页中国科学（信息科学）（英文版）

基　　金：supported by National Natural Science Foundation of China(Grant No.61274085);Science and Technology Research Projects of Guangdong Province(Grant No.2015B090909001)

摘　　要：Based on the drift-diffusion theory, a simple threshold voltage and drain current model for symmetric dual-gate（DG） amorphous In Ga Zn O（a-IGZO） thin film transistors（TFTs） is developed. In the subthreshold region, most of the free electrons are captured by trap states in the bandgap of a-IGZO, thus the ionized trap states are the main contributor to the diffusion component of device drain current. Whereas in the above-threshold region, most of the trap states are ionized, and free electrons increase dramatically with gate voltage, which in turn become the main source of the drift component of device drain current. Therefore,threshold voltage of DG a-IGZO TFTs is defined as the gate voltage where the diffusion component of drain current equals the drift one, which can be determined with physical parameters of a-IGZO. The developed threshold voltage model is proved to be consistent with trap-limited conduction mechanism prevailing in a-IGZO, with the effect of drain bias being also taken into account. The gate overdrive voltage-dependent mobility is well modeled by the derived threshold voltage, and comparisons of the obtained drain current with experiment data show good verification of our model.Based on the drift-diffusion theory, a simple threshold voltage and drain current model for symmetric dual-gate（DG） amorphous In Ga Zn O（a-IGZO） thin film transistors（TFTs） is developed. In the subthreshold region, most of the free electrons are captured by trap states in the bandgap of a-IGZO, thus the ionized trap states are the main contributor to the diffusion component of device drain current. Whereas in the above-threshold region, most of the trap states are ionized, and free electrons increase dramatically with gate voltage, which in turn become the main source of the drift component of device drain current. Therefore,threshold voltage of DG a-IGZO TFTs is defined as the gate voltage where the diffusion component of drain current equals the drift one, which can be determined with physical parameters of a-IGZO. The developed threshold voltage model is proved to be consistent with trap-limited conduction mechanism prevailing in a-IGZO, with the effect of drain bias being also taken into account. The gate overdrive voltage-dependent mobility is well modeled by the derived threshold voltage, and comparisons of the obtained drain current with experiment data show good verification of our model.

关 键 词：amorphous In Ga Zn O drift-diffusion current dual-gate thin film transistors threshold voltage 

分 类 号：TN321.5[电子电信—物理电子学]