Electrical properties of the Sm2Ti2O7 thin films for metal-insulator-metal capacitor applications

A homogeneous crystalline Sm2Ti2O7 (ST) phase was formed in films grown at temperatures ranging between 100 and 200 degrees C and subsequently annealed at 900 degrees C. The ST film had a large dielectric constant of 58, which is similar to that of ST ceramics. The leakage current density of the ST film was low and the Poole-Frenkel emission was suggested as being the leakage current mechanism. The ST film had a negative quadratic voltage coefficient of capacitance (VCC), possibly due to the dipolar relaxation. The 100-nm-thick ST film had a high capacitance density of 5.2 fF/mu m(2) with a low leakage current density of 1.34 nA/cm(2) at 2 V. Its quadratic and linear VCCs were -99.5 ppm/V-2 and 11 ppm/V, respectively, with a low temperature coefficient of capacitance of 135 ppm/degrees C at 100 kHz. These results confirmed the potential for the ST film to be used as a high performance metal-insulator-metal capacitor. (c) 2007 American Institute of Physics.