Thickness-ratio-dependent dielectric properties of Bi1.5Zn1.0Nb1.5O7/Ba0.5Sr0.5TiO3 bilayered thin films

• Thickness-ratio-dependent dielectric properties of BZN/BST films were investigated.
• The presence of BZN films effectively reduced the dielectric loss of the thin films.
• Thickness-ratio-dependent dielectric behaviors were described by simple equations.
• The optimal thickness ratio of BZN layer to BST layer was determined to be 0.5.
• A built-in electric field was established at the region near the BZN–BST interface.

Bi1.5Zn1.0Nb1.5O7 (BZN)/Ba0.5Sr0.5TiO3 (BST) thin films were prepared on Pt/Ti-coated sapphire substrates by radio frequency magnetron sputtering. The specific relationship between the dielectric properties and the thickness ratio of the BZN thickness to the BST thickness was investigated. The presence of BZN films effectively reduced the dielectric loss of the thin films. The thickness-ratio-dependent dielectric constant and dielectric loss behaviors were in good accordance with the simulation results based on the series connection theory. The optimum thickness ratio was determined to be around 0.5, exhibiting a maximum commutation quality factor of about 16,000. The built-in electric field at the region near the BZN–BST interface may be responsible for the asymmetric characteristic of the electric-field-dependent dielectric properties of the BZN/BST thin films.