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

Abstract

With the addition of TiO2, the dielectric constant (εr) 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 1.0 mol% TiO2-doped B5N3 (TBN) films. At low beam energy densities (⩽2.0 J cm−2), Bi3NbO7 and Bi8Nb18O57 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 εr 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 0.5 MV cm−1 and a high breakdown field of 0.55 MV cm−1. This improvement in the εr 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.