RF Cathodic Sputtering Research Articles

Features of the crystal structure and nanostructure of BFO/SBN/SRO/MgO(001) two-layer films fabricated by RF cathode sputtering

Structure, surface morphology, and magnetic properties of Sr0.6Ba0.4Nb2O6 film and BiFeO3/Sr0.6Ba0.4Nb2O6 heterostructures with different BiFeO3 thicknesses were studied. The heterostructures were fabricated by RF-cathode sputtering on a SrRuO3/MgO(001) substrate. According to X-ray diffraction data for BiFeO3/Sr0.6Ba0.4Nb2O6/SrRuO3/MgO(001), the BiFeO3 layer had a tensile strain of the unit cell up to 0.43%. Atomic force microscopy showed that the surface of the heterostructures had a low roughness and was represented by growth blocks, the average size of which did not exceed 91 nm. The results of magnetic force microscopy showed a clear magnetic response in BiFeO3/Sr0.6Ba0.4Nb2O6/SrRuO3/MgO(001) heterostructures for 30-150 nm thick BiFeO3 layer.

Phase composition, crystal structure and ferroelectric properties of Sr0.6Ba0.4Nb2O6/Ba2NdFeNb4O15/si(001) heterostructures

Phase composition, nanostructure and properties of Sr0.6Ba0.4Nb2O6/Ba2NdFeNb4O15/Si(001) heterostructures have been studied by X-ray diffraction, scanning probe microscopy, and dielectric spectroscopy. Sr0.6Ba0.4Nb2O6 and Ba2NdFeNb4O15 films were fabricated under identical conditions by RF cathode sputtering in an oxygen atmosphere. It was shown that the obtained heterostructures were pure, the Sr0.6Ba0.4Nb2O6 and Ba2NdFeNb4O15 layers were polycrystalline textured, and the layer thickness did not affect the unit cell strain. The heterostructure exhibited a ferroelectric-like response, but the polarized regions arising under the application of electric field were unstable at room temperature. The reasons for the identified regularities are discussed.

Obtaining, structure and energy efficiency under field exposure of a Ba2NdFeNb4O15/Sr0.6Ba0.4Nb2O6 bilayer heterostructure

The results of the structure and dielectric characteristics studies of the Ba2NdFeNb4O15/Sr0.6Ba0.4Nb2O6/SrRuO3/MgO(001) multilayer heterostructure are presented. Nano-sized films of multiferroic Ba2NdFeNb4O15, ferroelectric Sr0.6Ba0.4Nb2O6, and conductive SrRuO3 were deposited by RF cathode sputtering in an oxygen atmosphere in separate sputtering units. It was established that all layers of the heterostructure were grown as single-crystals and had a high structural perfection. The degradation of the ferroelectric parameters of the heterostructure was practically not detected up to 1010 switching cycles, while they were characterized by high energy efficiency.

Structure and surface morphology of barium-neodymium ferroniobate films

The paper presents the study results of barium-neodymium ferroniobate films with a thickness of 180 and 980 nm obtained by RF cathode sputtering. Using X-ray diffraction and magnetic force microscopy, we found that the films are single-phase, epitaxial and do not contain magnetic impurities. Atomic force microscopy data show that the films grow according to the Volmer-Weber mechanism.

Obtaining, crystal structure and nanostructure of Ba2NdFeNb4O15 heteroepitaxial films fabricated by RF sputtering on MgO(001) substrates

The high quality Ba2NdFeNb4O15 epitaxial films with thicknesses varying from 10 nm to 1 μm have been fabricated by RF cathode sputtering. The films were characterized by the formation of orientational domains with 18.4° in-plane rotation and tetragonal unit cell. The films have a smooth surface, while the presence of orientational domains does not manifest itself in any way on the surface relief. The obtained films have no magnetic response due to the absence of magnetic inclusions of barium hexaferrite. The absence of any impurities has been confirmed by x-ray diffraction, atomic force microscopy and energy dispersive elemental analysis.

Investigation of the Optical Properties of a BiFeO3/SrTiO3 Heterostructure Grown on an Al2O3(0001) Substrate by RF Cathode Sputtering

Investigation of the Optical Properties of a BiFeO3/SrTiO3 Heterostructure Grown on an Al2O3(0001) Substrate by RF Cathode Sputtering

Textured Ba2NdFeNb4O15 thin films on Si(001) substrate

A series of Ba2NdFeNb4O15 thin films with a thickness from 75 nm to 1 μm on Si(001) substrates was fabricated by RF-cathode sputtering. The surface of the films was smooth and uniform. Ba2NdFeNb4O15/Si(001) thin films were polycrystalline with the c-axis texture. A significant increase in the lattice parameter c of the films was found in comparison with the bulk sample. It was found that an external field action could create polarized regions in both thin and thick films, but rapid relaxation of these regions took place.

Dielectric response and ferroelectric properties of c-oriented barium-neodymium ferroniobate films

Studies of the dielectric and ferroelectric properties of c-oriented Ba2NdFeNb4O15 films is carried out at T = −190…200 °C using dielectric spectroscopy methods and ferroelectric hysteresis loops analysis. The films were obtained by RF-cathode sputtering method in an oxygen atmosphere. The PA-FE phase transition region, the features of the dielectric response formation, and the mechanisms responsible for that formation are revealed in the material. It is shown that the studied materials are characterized by high values of energy efficiency parameters. The reasons of the revealed regularities and the prospects of the use of these materials are discussed.

Ferroelectric properties of Sr0.5Ba0.5Nb2O6 thin films grown on a Si(001) substrate by RF cathode sputtering

Using the RF cathode sputtering method, ferroelectric films of barium-strontium niobate Sr0.5Ba0.5Nb2O6 were synthesized on a semiconductor substrate. Their phase composition, crystal structure, nanostructure, dielectric, and ferroelectric characteristics were studied. The temperature ranges of phase transformations, the characteristic values of spontaneous polarization and coercive fields, the magnitude and nature of the change in the imaginary and real parts of the complex permittivity in the temperature range −190 ÷ 250 °C were established in the films. The reasons for the revealed regularities are discussed.

Фазовый состав, кристаллическая структура, диэлектрические и сегнетоэлектрические свойства тонких пленок Ba-=SUB=-2-=/SUB=-NdFeNb-=SUB=-4-=/SUB=-O-=SUB=-15-=/SUB=-, выращенных на подложке Si(001) в атмосфере кислорода

The phase composition, nanostructure, and properties of Ba2NdFeNb4O15/Si(001) multiferroic thin films have been studied by X-ray diffraction analysis, scanning probe microscopy, and capacitance-voltage characteristics analysis. The RF cathode sputtering in an oxygen atmosphere was used for films fabrication. It has been found that the obtained Ba2NdFeNb4O15 films are single-phase, impurity-free, polycrystalline textured (c-oriented), and the out-of-plane strain is 0.8%, which leads to the presence of ferroelectric properties at room temperature. It is shown that the surface roughness of the films is ~ 15.39 nm, the lateral size of the crystallites is ~ 134 nm, and the relative permittivity in the temperature range of -190…150 °C is 95-130. The reasons for the revealed regularities are discussed.

Structure and optical properties of STO/Si and BFO-PFN/STO/Si heterostructures obtained by RF-cathode sputtering

The paper provides information on the growth of SrTiO3/Si (001) (STO/Si) and 0.5BiFeO3–0.5PbFe0.5Nb0.5O3/SrTiO3/Si (001) (BFO-PFN/STO/Si) composite heterostructures. BFO–PFN/STO/Si composite thin films were deposited on Si substrate by RF-cathode sputtering using STO as buffer layer for textured growth. The use of STO enhanced the orientation for the perovskite phase growth of the BFO–PFN films, which was confirmed by XRD. It was shown that the BFO–PFN layer in the BFO–PFN/STO/Si heterostructures suffered a strain and thus their physical properties were modified. The optical properties of the STO/Si pseudo-substrate were studied in detail.

Investigation of the optical properties of a BiFeO-=SUB=-3-=/SUB=-/SrTiO-=SUB=-3-=/SUB=- heterostructure grown on an Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-(0001) substrate by RF cathode sputtering

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. Keywords: thin films, multiferroic, optical properties, ellipsometry, bismuth ferrite.

Structure, dielectric and ferroelectric properties of Ba-=SUB=-2-=/SUB=-NdFeNb-=SUB=-4-=/SUB=-O-=SUB=-15-=/SUB=- multiferroic thin films

The phase composition, nanostructure, and properties of Ba2NdFeNb4O15 multiferroic thin films are studied by X-ray diffraction, dielectric spectroscopy, methods for analyzing ferroelectric properties, and scanning probe microscopy. Films were grown on the single-crystal Pt/MgO(001) substrate by a one-stage RF cathode sputtering technique in an oxygen atmosphere. It has been established that the Ba2NdFeNb4O15 films are single-phase, impurity-free, and c-oriented, which made it possible to study their dielectric properties along the polar direction. tensile deformation of the unit cell (1.35% along the polar axis) has found in the films, which led to the realization of the ferroelectric phase in the BNFNO film at room temperature. The revealed dependencies and the prospects for using this material in the nanosized thin films form are discussed. Keywords: multiferroic, dielectric characteristics, ferroelectric, tetragonal tungsten bronze.

Optical properties of SrxBa1−xNb2O6 nanoscale films (x = 0.5 and 0.61) grown by RF-cathode sputtering in an oxygen atmosphere

The research findings of the phase composition, nanostructure and optical properties of strontium–barium niobate thin films are discussed. [Formula: see text]Ba[Formula: see text]Nb2O6 nanosized films ([Formula: see text] = 0.5 and 0.61) were characterized by XRD, SEM and AFM studies. Reflective multi-angle ellipsometry and spectrophotometry were used to determine the optical parameters (refractive index, its dispersion, and thickness of the damaged surface layer) of thin films. It was shown that SBN-50 and SBN-61 thin films were grown [Formula: see text]-oriented on Al2O3 (0001) and heteroepitaxial on MgO (001) substrates. The increase of refractive index, approaching its maximum value in the bulk material for a given composition as the film thickness increases, is observed.

Preparation and properties of 0.5BiFeO3–0.5PbFe0.5Nb0.5O3 ceramics and polycrystalline films

In this paper, we report the successful growth of 0.5BiFeO3–0.5[Formula: see text][Formula: see text]O3/SrTiO3/Si(001) heterostructure using RF-cathode sputtering in an oxygen atmosphere. The deposited films have been investigated by X-ray diffractometry and spectroscopic ellipsometry (SE). 0.5BiFeO3–0.5[Formula: see text][Formula: see text]O3 films on silicon substrates with a strontium titanate buffer layer are single-phase, polycrystalline with a texture in the 001 direction. The unit cell parameters calculated in the tetragonal approximation were [Formula: see text] = 4.005 ± 0.001 [Formula: see text]; [Formula: see text] = 3.995 ± 0.001 [Formula: see text]. The presence in the films of small unit cell deformation arising from different unit cells parameters of the film and substrate is observed. Dielectric properties and capacitance-voltage characteristics have been measured. The ellipsometric parameters have been obtained.

Effect of Substrate Bias on the Crystal Structure and Morphology of Barium Strontium Niobate Films Grown by RF Cathode Sputtering

Barium strontium niobate films have been grown on MgO(001) substrates by single-step rf cathode sputtering of a ceramic target with the stoichiometric composition Sr0.5Ba0.5Nb2O6 in an oxygen atmosphere under various conditions (at different substrate biases). It has been shown that, depending on its polarity, the substrate bias either increases or reduces the flux of structure-forming elements to the substrate and, as a consequence, changes the growth rate, without impairing the surface morphology or surface perfection of the film or producing impurity phases. The mechanisms underlying the observed general relationships are discussed.

Structural Characteristics of Sr0.61Ba0.39Nb2O6/MgO(001) Thin Films Grown by RF-Cathode Sputtering

Structural Characteristics of Sr0.61Ba0.39Nb2O6/MgO(001) Thin Films Grown by RF-Cathode Sputtering

Диэлектрические и сегнетоэлектрические свойства тонких гетероэпитаксиальных пленок SBN-50

The phase transformations and ferroelectric characteristics of thin heteroepitaxial barium-strontium niobate SBN-50 films grown by RF cathode sputtering in an oxygen atmosphere were studied using dielectric spectroscopy and scanning probe microscopy (in the modes of force microscopy of the piezoresponse and Kelvin modes). It is shown that the films are characterized by a low surface roughness, an average size of ferroelectric domains of ~ 100 nm, and spontaneous polarization directed from the substrate to the film surface. Differences in the magnitude of the surface potential signal and its relaxation for the regions polarized at +10 V and –10 V were established. The nature of the change in the dielectric parameters in the temperature range T = 275–500 K indicates that the material belongs to ferroelectric relaxors. The reasons for the established regularities are discussed.

Структурные характеристики выращенных методом RF-катодного напыления тонких пленок Sr-=SUB=-0.61-=/SUB=-Ba-=SUB=-0.39-=/SUB=-Nb-=SUB=-2-=/SUB=-O-=SUB=-6-=/SUB=-/ MgO(001)

Thin films of the congruent composition of the barium-strontium niobates solid solutions Sr0.61Ba0.39Nb2O6 (SBN: 61) with thicknesses from 30 to 630 nm on a MgO (001) substrate were fabricated by RF-cathode sputtering in an oxygen atmosphere. By X-ray diffraction it was found that the films are epitaxial and there are no impurities in them. In the films, there is practically no unit cell deformation in the interface plane and tensile strain is present in the normal to the surface direction, which increases with decreasing film thickness. Dielectric measurements indicate high tunability in the films.

Effect of Li2CO3 modification on formation of ferroelectric properties of PbFe0.5Nb0.5O3 ceramic targets and thin films prepared by RF cathode sputtering

Abstract The paper presents the results of characterization of the crystal structure, microstructure, dielectric and piezoelectric properties of PbFe0.5Nb0.5O3 ceramics modified at the stage of synthesis by lithium carbonate. Due to a detailed analysis of relaxation processes and piezoelectric activity in the region of the ferroelectric to paraelectric state transition, conclusions are drawn about the optimal concentration of the modifier as well as, from the standpoint of mass production technology, the prospects for using such ceramics as targets for producing single-phase thin films of lead ferroniobate on Si substrates as part of a one-stage method of high-frequency cathodic deposition in O2 atmosphere are shown. The features of the formation of C(U) dependences and the fatigue effect, which are manifested during cyclic field action on the obtained heterostructures, were studied.