The structure and optical characteristics of thin films of relaxor ferroelectric Ba_0.5Sr_0.5Nb_2O_6 grown by RF sputtering in an oxygen atmosphere on an Al_2O_3 substrate ( c cut) have been studied. X-ray diffraction analysis shows that Ba_0.5Sr_0.5Nb_2O_6 films are c -oriented and unit-cell parameter c is 3.948(1) Å. Ellipsometric measurements confirm that SBN-50 films are characterized by a natural growth direction, which coincides with the direction of the optical crystal axis. An analysis of ellipsometric results shows that there is no transition layer at the film/substrate interface; the damaged layer on the free film surface is 7.5 nm thick, and the volume filling factor is estimated to be 0.625.

Представлены результаты эллипсометрических измерений оптических параметров наноразмерных сегнетоэлектрических пленок ниобатов бария-стронция Sr0,5Ba0,5Nb2O6 (SBN-50) / Al2O3 (0001) и Sr0,61Ba0,39Nb2O6 (SBN-61) / MgO (001) разной толщины. Установлено, что все пленки эпитаксиальные с направлением роста, параллельным полярной оси с кристалла. Определены показатели преломления, толщины базового и нарушенного слоев каждой из пленок, установлены закономерности свойств пленок в зависимости от их толщины.

The phase composition, structure, and optical properties of the BiFeO3/SrTiO3/Al2O3 (c-cut) heterostructure have been studied using XRD analysis, spectrophotometry, and multi-angle ellipsometry. BFO/STO/Al2O3 heterostructures have been obtained by high-frequency cathode sputtering in an oxygen atmosphere using the intermittent deposition technology. It was found that the BiFeO3 and SrTiO3 layers grew with an orientation in the direction of the [111] crystallographic axis parallel to the normal to the Al2O3 substrate. It has been shown that the damaged layer on the surface of the heterostructure does not exceed 2–3 nm, and no signs of the presence of boundary layers at the Al2O3– SrTiO3 and SrTiO3– BiFeO3 interfaces have been identified. The dispersion dependences of the refractive indices of BFO and STO layers are calculated. The reasons for the revealed regularities are discussed.