Research On Nonlinear Current-voltage Characteristic And Restoration Hysteresis Effect Of CaCu₃Ti₄O₁₂ Thin Films

CaCu₃Ti₄O₁₂（CCTO）has attracted much attention due to its excellent dielectric properties.As the research continues,the obvious nonlinear current-voltage（I-V）behavior is being paid close attention.Compared with traditional varistor materials,the threshold voltage of CCTO is lower and the nonlinear parameters is higher,these characteristics could be satisfied with the requirements of the varistor in integrated circuit,and it is a very promising material for the application in microelectronics.In this work,CCTO precursor solution was prepared through sol-gel method,and combined with spin coating method to prepare CCTO films.The phase identification of the film have been characterized using X-ray diffractometer,and field emission scanning electron microscope were used to observe the surface morphology of the film,a semiconductor parameter analyzer was used to determine the electrical properties of the film.In order to investigate the influence of different preparation conditions on the electrical properties,the contrast experiments with different sintering temperatures,substrates,annealing environments and Ni ions doping were conducted.At the same time,the restoration hysteresis effect were reported for the first time,and the effect of different preparation conditions on restoration hysteresis effect was analyzed.The experimental results show that the substrates have a big influence on nonlinear I-V behavior of CCTO films,the minimum threshold voltage was obtained when CCTO films prepared on Pt/Ti/SiO₂/Si substrate.With the increase of sintering temperature,the threshold voltage decrease obviously.When the as-sintered films were then treated by rapid thermal process（RTP）in oxygen-rich atmosphere at 600^oC,the threshold voltage tend to increase,and the longer the time of RTP,the higher the threshold voltage.Ni ions doping in CCTO films could also increase the threshold voltage.Meanwhile,the results of restoration hysteresis effect indicated that the initial current tended to increase as sintering temperature increased,and RTP in oxygen atmosphere could decrease initial current.Based on double Schottky barrier model and tunneling effect,the excellent electrical behavior of CCTO film were fully explained.