Non-Ohmic behavior of copper-rich CCTO thin film prepared through magnetron sputtering method

CaCu_3+xTi₄O_12+x (x = 0, 0.1, 0.2, 0.4, 0.8) thin films with obvious non-Ohmic behaviors were prepared through magnetron sputtering method. The second phase of CuO and TiO₂ were detected in all Cu-rich ceramic targets, and CuO was detected in thin film sample when x = 0.8 which contributed to the increased grain size. The nonlinear I–V behaviors were explained by Schottky emission and Poole–Frenkel electrons transportation mechanism. The nonlinear coefficient increased with x, reached the maximum when x = 0.4 and then decreased, which is in accordance with the changing trend of trap barrier height, meaning that Poole–Frenkel model can describe the non-Ohmic behaviors of Cu non-stoichiometric samples better than Schottky emission model.