Pressure Dependence of C–V Curve for Ferroelectric PbTiO3 Thin Films Prepared by RF Multi‐target Magnetron Sputtering

Lead titanate thin films were prepared in‐situ by RF magnetron sputtering method in the substrate temperature region of 550 °C ˜ 650 °C using Ti and Pb metal targets and oxygen gas. The films deposited at 650 °C for 60 min – when the applied power to the Ti and Pb target and deposition pressure were 200 W, 40 W, and 1.8 × 10−2 Torr, respectively — had stoichiometric composition ratio and shown X‐ray diffraction patterns of tetragonal structure like that of the powder. For the application to the piezoelectric field effect transistor (PI‐FET), the substrate of SiO2 (50 nm)/p‐Si(100) was used. Leakage current density of the thin film was 7 × 10−8 A/cm2 at 100 kV/cm, dielectric breakdown voltage was 1.8 MV/cm, and so it showed high insulator characteristics. Capacitance‐voltage curve was measured as a function of pressure. The variation width of the capacitance was 6.5 pF at bias voltage of –4 volts, and the value increased linearly according to the pressure up to about 6 kgf/cm2, and was saturated at the pressure of 8 kgf/cm2.