Low electrical field induced oriented growth of ferroelectric LiNbO3 thin films and multilayers

Abstract

A low electrical field applied during pulsed laser deposition of ferroelectric thin films or multilayers has a significant influence on the texture of the ferroelectric films and layers, leading to an oriented growth with the poling direction of the films parallel to the applied electrical field. Highly (001) oriented LiNbO3 films have been prepared in a bias electrical field less than 10V/cm on different kinds of substrates. With the help of this method a series of (001) LiNbO3 / amorphous A12O3 multilayers with modulation period of several nm to several hundred nm were prepared sucessfully. In these “acoustic superlattices” the piezoelectric coefficient modulation has been achieved and the acoustic resonances up to 9.8 GHz were demonstrated. The impact of the low electrical field on the orientation of the ferroelectric films prepared by pulsed laser deposition has been analysed based on the theory of heterogeneous nucleation of ferroelectrics under the influence of the applied electric field.