Influence of thermal treatment on the nonlinear current–voltage behavior and restoration hysteresis effect of CaCu3Ti4O12 thin films

Abstract

CaCu3Ti4O12 (CCTO) thin films were prepared through sol–gel method. The influences of sintering temperature and rapid thermal process (RTP) in oxygen-rich atmospheres on its nonlinear current–voltage (I–V) behavior and restoration hysteresis effect were investigated. The phase identification of the films was characterized by using X-ray diffractometer, the results show that in the as-sintered films which were treated through RTP in oxygen atmospheres, a weak CuO and TiO2 diffraction peaks could be detected. Field emission scanning electron microscope was performed to observe the microstructure of the films. A semiconductor parameter analyzer was used to determine the I–V behaviors. The results show that with sintering temperature increase, the threshold voltages of CCTO thin films decreased significantly. After the films were treated through RTP in oxygen-rich atmosphere, the height of Schottky barriers would increase obviously, resulting in the increase of threshold voltages of CCTO films, and the longer the time of RTP, the higher the Schottky barrier. The influence of RTP on restoration hysteresis effect of CCTO films was reported for the first time, and RTP could decrease the initial current and increase the resistivity. The double Schottky barrier model and the tunnel junction model were used to explain these phenomena, and the conduction mechanism in CCTO film was discussed to describe the restoration hysteresis effect.