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pp.574-579
Amorphous BaTi4O9 (BT4) film was deposited on Pt/Si substrate by RF magnetron sputter and their dielectric properties and electrical properties are investigated. A cross sectional SEM image and AFM image of the surface of the amorphous BT4 film deposited at room temperature showed the film was grown well on the substrate. The amorphous BT4 film had a large dielectric constant of 32, which is similar to that of the crystalline BT4 film. The leakage current density of the BT4 film was low and a Poole-Frenkel emission was suggested as the leakage current mechanism. A positive quadratic voltage coefficient of capacitance (VCC) was obtained for the BT4 film with a thickness of<70 nm and it could be due to the free carrier relaxation. However, a negative quadratic VCC was obtained for the films with a thickness ≥96nm, possibly due to the dipolar relaxation. The 55 nm-thick BT4 film had a high capacitance density of 5.1fF/μm2 with a low leakage current density of 11.6nA/cm2 at 2 V. Its quadratic and linear VCCs were 244ppm/V2 and -52 ppm/V, respectively, with a low temperature coefficient of capacitance of 961ppm/˚C at 100 kHz. These results confirmed the potential suitability of the amorphous BT4 film for use as a high performance metal-insulator-metal (MIM) capacitor.
