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BaTi4O9 thin films were grown on a Pt/Ti/SiO2/Si substrate using RF magnetron sputtering. A homogeneous BaTi4O9 crystalline phase developed in the films deposited at 550∘C and annealed above 850∘C. When the thickness of the film was reduced, the capacitance density and leakage current density increased. Furthermore, the dielectric constant was observed to decrease with decreasing film thickness. The BaTi4O9 film with a thickness of 62 nm exhibited excellent dielectric and electrical properties, with a capacitance density of 4.612 fF/μm2 and a dissipation factor of 0.26% at 100 kHz. Similar results were also obtained in the RF frequency range (1–6 GHz). A low leakage current density of 1.0 × 10−9 A/cm2 was achieved at ± 2 V, as well as small voltage and temperature coefficients of capacitance of 40.05 ppm/V2 and –92.157 ppm/∘C, respectively, at 100 kHz.

A high capacitance density of 4.84 fF/mum2 and a low leakage current density of 4.28 fA/pFmiddotV were obtained for a 138-nm-thick crystalline BaSm2Ti4O12 (BST) film. The 100-nm-thick amorphous BST film exhibited a high capacitance density of 3.91 fF/mum2 and a low leakage current of 1.24 fA/pFmiddotV. The crystalline BST film had quadratic and linear voltage coefficient of capacitance (VCC) of -295 ppm/V2 and 684 ppm/V, respectively, and a temperature coefficient of capacitance (TCC) of -136 ppm/degC at 100 kHz. The amorphous BST film also showed quadratic and linear VCCs of 48.6 ppm/V2 and -738 ppm/V, respectively, with a low TCC of 169 ppm/degC at 100 kHz

The dielectric and electrical properties of a BaTi4O9 film were investigated in order to evaluate its potential use in metal-insulator-metal (MIM) capacitors for rf/mixed signal integrated circuits. A high capacitance density of 4.62fF∕μm2 along with a low tanδ of 0.0025 were obtained at 100 kHz. A high capacitance density of 4.12fF∕μm2 and a high quality factor of 322 were also achieved at 2 GHz. The leakage current density was approximately 1nA∕cm2 at ±2V. Small linear and quadratic voltage coefficients of capacitance of 110ppm∕V and 40.05ppm∕V2, respectively, and a small temperature coefficient of capacitance of −92.157ppm∕°C at 100 kHz were obtained. These results demonstrate that the BaTi4O9 film is a good candidate material for MIM capacitors.