Effect of laser beam energy density on the structural and electrical properties of TiO₂-doped Bi₅Nb₃O₁₅ thin film grown by pulsed laser deposition

With the addition of TiO₂, the dielectric constant (ε_r) of a Bi₅Nb₃O₁₅(B5N3) film was slightly increased and the leakage current decreased, probably due to the increased dipole moment and the decreased number of free electrons in the film, respectively. The energy density of the laser beam considerably influenced the structure and electrical properties of the 1.0mol% TiO₂-doped B ₅N₃ (TBN) films. At low beam energy densities (≤2.0 J cm^-2), Bi₃NbO₇ and Bi₈Nb ₁₈O₅₇ phases with a porous microstructure were formed and a poor interface was also formed between the film and the electrode. However, for the TBN film grown at 200 °C at a high beam energy density of 4.0 J cm^-2, a dense Bi₃NbO₇ phase was formed with a sharp interface. The ε_r value of this TBN film was very high, approximately 115, with a low leakage current density of 1.4 × 10 ^-8 A cm^-2 at 0.5MVcm^-1 and a high breakdown field of 0.55 MVcm^-1. This improvement in the ε_r value and the electrical properties was explained by the formation of a dense Bi₃NbO₇ phase with a (1 1 1) preferred orientation, Ti doping and a sharp interface, indicating that the TBN film is a good candidate material for embedded capacitors.