Study On Solution Processing Method Of Laminated Dielectrics And Active Layer For Thin Film Transistor

Solution-process has been widely used in the preparation of Metal oxide thin film transistors?MOTFTs?in recent years because of its low cost and simple operation.This thesis mainly studies the dielectric and active layer based on the laminated-structure fabricated by spin-coated to resolve the problems of the traditional dielectric and semiconductor.Firstly,the preparation-process of laminated dielectric was studied.The properties of thin films changing with annealing temperature and concentration of precursors is explored,and the properties-adjustable Al₂O₃/ZrO₂ laminated dielectric was achieved finally.It was found that the properties of laminated dielectric is relative stable when the ratio of Al₂O₃ is higher than 50%,while the variation of the optical energy band,dielectric strength,capacitance density and permittivity is up to 0.482 eV,2.12 MV cm^-1,135.35 nF cm^-2 and 11.64,respectively,when the ratio of Al₂O₃ varying from 0%to 50%.Furthermore,because the grain boundaries are interrupted by amorphous alumina,the dielectric strength of laminated dielectric is improved significantly by increasing the number of bilayers.Then,the laminated active layer was studied based on the process of nanolaminates.Given the difference between the solution process and vacuum process,the laminated active layer based on the model of In₂O₃/In_xM_yO_z was proposed.An In₂O₃/In_xAl_yO_z-TFT was realized finally and the result shows that the TFT has a threshold voltage(V_th)of 2.69 V,an on/off current ratio of 6.54×10⁷,a subthreshold swing?SS?of 0.407 V dec^-1,and a mobility of 1.37 cm² V^-1 s^-1.Meanwhile,the V_th shift of In₂O₃/In_xM_yO_z-TFT under the PBS is only 2 V,which is superior to the 20 V of In₂O₃-TFT.However,the electric stability under the NBS is performed badly.To suppress the electron generated by donor-like impurities,another laminated active based on the structure of In₂O₃/In_xAl_yO_z/Al₂O₃ was proposed,but the In₂O₃/In_xAl_yO_z/Al₂O₃-TFT shows bad electric properties.Therefore,the fabrication-process and theoretical analysis of In₂O₃/In_xAl_yO_z/Al₂O₃ need to be improved in the subsequent experiments.