The effect Of SiO2 barrier layer on the dielectric properties of CaCu3Ti4O12 films

CaCu3Ti4O12 (CCTO) film is attractive for microelectronic device applications due to its high dielectric constant. However, its dielectric loss has to be lowered. In this study, a thin layer SiO2 was inserted into the CCTO films prepared on Pt/Ti/SiO2/Si substrates by the pulsed laser deposition method, in an effort to reduce the dielectric loss. The SiO2 thin layers are located in the bottom, middle and top of the films, respectively. Compared with the single layer CCTO films, the CCTO/SiO2 multilayers exhibit lower dielectric loss while maintaining an adjustable dielectric constant. Both the microstructure and dielectric properties were found to be strongly dependent on the position of the SiO2 thin layer, showing that the SiO2 thin layer acts not only as a barrier layer but also an initial nucleation layer of the CCTO thin films. The CCTO film with a SiO2 layer in the middle shows the lowest dielectric loss (0.06 at 100 kHz) and leakage current (4.4 x 10(-6) A cm(-2) at 100 kV cm(-1)), while the dielectric constant is 171 at 100 kHz.