A Physical Charge-Based Model for Transient Response of Metal Oxide Thin-Film Transistors Considering Relaxation of Trap States

This article proposed a charge-based model for the transient response of metal oxide thin-film transistors (MO-TFTs), which takes into account energy band redistribution and the relaxation behavior of trap states. In this model, a relaxation equation of trapped charge is obtained according to Shockley-Read-Hall (SRH) emission capture theory and mathematical derivations. Furthermore, combined with the voltage distribution relationship and charge conservation, the microscopic relaxation process of trapped charge can be related to the macroscopic transient characteristics of MO-TFTs. A transient test system is built, and MO TFTs with an etch stop layer (ESL) structure are fabricated to verify the proposed model. It is shown that there is a good agreement between the measured data and the simulated results calculated by the proposed model. Consequently, the charge capture coefficient {r}_{Q} is extracted as 2.5\times 10^{{13}} cm ^{{2}} \cdot s ^{-{1}} \cdot C ^{-{1}} from the relaxation time of the transient current.