Bi₂MoO₆ dielectric thin films fabricated by thermal oxidation of Bi/Mo thin films at ultra-low temperature

Bi/Mo multilayer thin films are deposited on Si/SiO₂/Pt substrates by direct current magnetron sputtering. The effect of annealing temperature on the microstructure, dielectric and electrical properties of the as-sputtered films is characterized systematically. X-ray diffraction data indicate that the films annealed at 450–600 °C are a mixture of diphase with the main phase Bi₂MoO₆ and secondary phase Bi₂Mo₂O₉. Results of scanning electron microscope observation show that the films annealed at 500–550 °C are dense and uniform, in particular the films annealed at 500 °C exhibit optimal dielectric and electrical properties with dielectric constant as high as 37.5, dielectric loss 1.06 %, temperature coefficient of dielectric constant −10.86 ppm °C⁻¹ at 1 kHz, and leakage current density of 1.46 × 10⁻⁷ A mm⁻² at an electric field of 18.2 kV mm⁻¹. With the advantages of ultralow densification temperature (500 °C) and very high sputtering deposition rate (76 nm min⁻¹), it is anticipated that thermal oxidation method of the sputtered Bi/Mo thin films could be a promising technique for fabrication of Bi₂MoO₆ ceramic thin film embedded-capacitors.