Most of ferroelectric devices, such as capacitors, IR detectors or ferroelectric random access memory (FeRAM) explore electric filed oriented perpendicular to the film (z-geometry). With a film thickness of tens or hundreds of nanometers ferroelectric polarization can be switched by very low voltage (1-5 V). In the same time for various applications, particularly for radiofrequency and optical applications, planar geometry is considered as more efficient because it provides better interaction for electromagnetic wave with ferroelectric polarization , and allows quite dense integration for such application. Planar geometry is widely used for MEMS as well. Presently radiofrequency phase rotators and phase antenna arrays are fabricated on the basis of semiconductor or ferrite materials. They already come closely to the limit of their parameters. Modern devices require higher operation frequency, lower optical and dielectric losses and lower costs. This was the reason for many researchers and companies to shift for developing of such applications to ferroelectric thin films and to in planar geometry, which fit to all abovementioned requirements. The goal for optoelectronics for nearest future is elaboration of ultrafast hybrid solid (electro)optical chip. A lot of research activities are focused on the developing different elements for it, both passive and active, such as electro-optical (EO) modulators. One of the main problems in film fabrication is to provide conditions for layer-by-layer growth, which results in a high quality single crystalline films of tens of nanometers thickness and atomic roughness. High quality of interfaces enables deposition of planar electrode system with submicron dielectric gaps and hence functioning at low voltage. These conditions guarantee high operation frequency (up to hundreds of GHz) and low losses, which is necessarily required for applications such as phase antenna arrays and modulators.