Electrical Properties of a 0.95( Na 0.5 K 0.5 ) NbO 3 –0.05 CaTiO 3 Thin Film Grown on a Pt / Ti / SiO 2 / Si Substrate

An amorphous phase was formed in a 0.95( Na 0.5 K 0.5 ) NbO 3 –0.05 CaTiO 3 (NKN‐CT) film grown at 300°C, and a low‐temperature transient Ca 2 Nb 2 O 7 phase was formed in the film grown at 500°C. In films grown at high temperatures (≥600°C), secondary phases such as K 5.75 Nb 10.85 O 30 and K 4 Ti 10 Nb 2 O 27 were developed without the formation of a NKN‐CT phase, probably because of Na 2 O evaporation. The same secondary phases were formed in the film grown at 300°C and subsequently annealed at 850°C under an air atmosphere. However, a homogeneous NKN‐CT phase was formed in films grown at 300°C and subsequently annealed at 830°C–880°C under the K 2 O and Na 2 O atmospheres. Moreover, the film annealed at 830°C in particular exhibited good electric and piezoelectric properties, including a high dielectric constant of 747 with a low dissipation factor of 0.93% at 100 kHz, low leakage current density of 2.0 × 10 −7  A/cm 2 at 0.1 MV/cm, and high P r and d 33 values of 15.4 μC/cm 2 and 124 pm/V at 100 kV/cm, respectively.