Epitaxial growth of (Bi,K)TiO₃-Bi(Mg,Ti)O₃(001) films and their ferroelectric and piezoelectric properties

Abstract

Epitaxial growth of 0.95(Bi 0.5 K 0.5 )TiO 3 -0.05Bi(Mg 0.5 Ti 0.5 )O 3 (BKT-BMT) films on silicon substrates at the morphotropic phase boundary composition has been achieved for the first time using pulsed laser deposition. Perovskite films with a cube-on-cube relationship grew on the platinum bottom electrode at a substrate temperature of 450 °C-550 °C. Both the Bi/(Mg + Ti) and K/(Mg + Ti) ratios decreased with increasing substrate temperature. A film with an approximately stoichiometric composition was obtained at a substrate temperature of 450 °C. The BKT-BMT film has a high lattice anisotropy parameter (c/a) of 1.048 because a large strain of 0.7%-1.0% is introduced into the film. Its remanent polarization (P r ) and coercive field (E c ) are 60 μC cm −2 and 200 kV cm −1 , respectively. The transverse piezoelectric coefficient (e 31,f ) of the BKT-BMT films is −2.2 C cm −2 . The BKT-BMT film has superior displacement linearity with regard to different electric fields.