Effect of laser beam energy density on the structural and electrical properties of TiO_2-doped Bi_5Nb_3O_(15) thin film grown by pulsed laser deposition

摘要

With the addition of TiO_2, the dielectric constant (ε_r) of a Bi_5Nb_3O_(15)(B_5N_3) 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% TiO_2-doped B_5N_3 (TBN) films. At low beam energy densities (≤2.0 J cm~(?2)), Bi_3NbO_7 and Bi_8Nb_(18)O_(57) 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 Bi_3NbO_7 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 0.5 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 Bi_3NbO_7 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