Structural and electrical properties of Bi2O3-Nb2O5 thin films grown at low temperatures by pulsed laser deposition

The dielectric constant (εr) of the films grown at 100 °C increased as the beam energy density increased and a saturated value of 80 was obtained for the film grown under 6.0 J cm−2. The larger εr value was attributed to the increased amount of nano-sized Bi3NbO7 crystals. The εr values also increased with the beam energy density for films grown at 300 °C and a very high εr value of 135.6 with a low loss of 3.0% at 100 kHz was obtained for the film grown at 300 °C under a beam density of 3.0 J cm−2. The crystalline BiNbO4 phase developed, but the amount of Bi3NbO7 crystals decreased as the beam energy density increased, indicating that the increased εr values of the films grown at 300 °C could be due to the formation of the crystalline BiNbO4 phase. The electrical properties of the films grown at 300 °C under a beam density of 3.0 J cm−2 were considerably influenced by the oxygen partial pressure (OPP) during annealing. The film annealed at 300 °C under a 50.0 torr OPP exhibited a low leakage current density of 5.4 × 10−9 A cm−2 at 0.3 MV cm−1 with a relatively high breakdown field of 0.4 MV cm−1.