Simulation Of Thin Film Transistor Properties With IGZO/IZO Double Active Layers

With the development of the flat-panel display technology,fabricating of high-performance display devices faces the challenge.The traditional thin-film transistor(TFT)technology has not been able to meet people's demands based on amorphous silicon(a-Si).In order to solve this problem,the development of novel materials instead of a-Si has never stopped.Such as organic or transparent oxide materials have been extensively explored.The amorphous-Indium-Gallium-Zinc-Oxide(a-IGZO)is probably to replace a-Si.Owing to the film has many unique properties,for example,high optical transparency and high electron mobility.Besides,large-area a-IGZO can be deposited on flexible substrate by low-temperature process.Thus,a-IGZO TFT has great potential values in the high-resolution display devices,sensor,and flexible electronic devices and so on.In order to improve the performance of a-IGZO TFT,a-IGZO TFT with dual-active layers structure has been deeply investigated.It is noticed that dual-active layers may form heterostructure,but it is rarely reported and discussed.This thesis considers that a-IGZO and the amorphous-Indium-Zinc-Oxide(a-IZO)have different band-gap and electron-affinity,the influence of the dual-active layers on the electrical properties of bottom-gate a-IGZO/IZO TFT is studied by ATLAS device module of SILVACO TCAD.The major content of this thesis can be summarized as follows1.Based on the heterostructure,the influence of the thickness ratio of dual-active layers on the electrical properties of a-IGZO/IZO TFT is studied.The simulation results show that the characteristics of a-IGZO/IZO TFT are closely related to the thickness ratio of dual-active layers and heterostructure.It is found that the thickness ratio of the active layer allows for adjustment in the the threshold voltage,subthreshold swing and maximum switching current ratio.The electrical properties of TFT can be optimized when the thickness ratio of the active layer is 20:20.2.Based on the previous study,the influence of the thickness of active layers on the electrical properties of a-IGZO/IZO TFT is further studied.1)The influence of the total thickness of double active layers on the electrical properties of a-IGZO/IZO TFT is studied.2)The influence of the thickness variation of a-IGZO on the electrical properties of a-IGZO/IZO TFT is studied.3)The influence of the thickness variation of a-IZO on the electrical properties of a-IGZO/IZO TFT is studied.The stimulation results show that the total thickness of dual-active layers should not more than 50 nm,and the thickness variation of a-IZO is more effective than the electrical properties of a-IGZO/IZO TFT.3.Based on the N type a-IGZO/IZO TFT and the building of the stated of density model of a-IGZO,the influence of the valence band donorlike deep states on the electrical properties of a-IGZO/IZO TFT is further studied.The stimulation results show that it has significant impact on the performance of a-IGZO/IZO TFT.This thesis mainly works on the model and simulation of IGZO/IZO TFT.It has important applied value and significance.It also has a certain referential value for the future research of a-IGZO/IZO TFT.