High-frequency Magnetron Sputtering Research Articles

Structural and morphological properties of CdSe1-xSx thin films obtained by the method of high-frequency magnetron sputtering

CdSe1-xSx (x= 0.3, 0.4 and 0.6) thin films were deposited on quartz and silicon substrates by the method of high-frequency magnetron sputtering. The chemical composition analysis and crystal structure refinement was examined with using X-ray fluorescence spectroscopy and X-ray diffraction data. CdSe1-xSx thin films crystallizes in hexagonal structure (structure type – ZnO, space group P63mc (No. 186)). The lattice parameters (a, c and V), crystallite size (D), strain (ε), dislocation density (δ) and the texture coefficient TC(hkl) was estimated from X-ray diffraction analysis. Units-cell parameters decrease with increasing S content in CdSe1-xSx thin film.

Growth and crystal structure of CdTe1−xSex (x ≥ 0.75) thin films prepared by the method of high-frequency magnetron sputtering

CdTe1–xSex (x = 0.75 and 0.95) thin films were deposited on quartz substrate by the method of high-frequency magnetron sputtering. The chemical composition analysis and crystal structure refinement was examined with using X-ray fluorescence spectroscopy and X-ray diffraction data. CdTe1–xSex thin films crystallizes in hexagonal structure [structure type—ZnO, space group P63mc (No. 186)]. Unit cell parameters decrease with increasing Se content in CdTe1–xSex thin films. The value of the optical band gap for CdTe0.25Se0.75 and CdTe0.05Se0.95 was estimating using the Tauc plot and from the maximum position of the first derivative of the transmittance dT/dλ.

Magnetron Deposition of Barium Hexaferrite Films from a Target of Stoichiometric Composition

A technique is proposed for obtaining films of barium hexaferrite on sapphire with (0001) orientation by high-frequency magnetron sputtering of a stoichiometric BaFe12O19 target followed by annealing. The X-ray diffraction analysis and Raman spectrometry carried out showed the possibility of crystallization of oriented films without using correction of the target composition.

Structure and Properties of Thin Magnetron Films of Cadmium Arsenide on Various Substrates

Purpose of the study. Synthesis of cadmium arsenide magnetron films on various substrates and study of their structure, composition, optical and electrical properties.Methods. The deposition of thin films of cadmium arsenide was carried out by the method of non-reactive highfrequency magnetron sputtering in an argon atmosphere. The structure and composition of the films were studied using X-ray phase analysis, scanning electron microscopy, energy dispersive analysis, and small-angle X-ray diffractometry. Optical studies were performed using Raman spectroscopy. The results of a study of the electrical properties of thin films of cadmium arsenide are presented.Results. On silicon, sapphire, and strontium titanate substrates, thin films of the Dirac semimetal, cadmium arsenide, were obtained with a thickness of about 40 nm. A study of their structure and composition showed a significant effect of annealing in an argon atmosphere following deposition on the crystallinity of the film. After annealing, regardless of the crystal structure of the substrate, partial orientation of the film with the (112) texture axis. The films closest to the stoichiometric composition were obtained by deposition followed by annealing onto an oriented strontium titanate substrate, and to the crystal structure of cadmium arsenide single crystals of a film on a sapphire substrate. Annealing also leads to a smoothing of the film surface, a decrease in structural defects, and the transition of the fractal dimension of its topology to two-dimensional from close to three-dimensional immediately after deposition. The optical properties after annealing also change, which indicates their transition from a polycrystalline (amorphous) state to a single-crystal (textured).Conclusion. Experimental studies of the structure and properties performed by various methods made it possible to establish that single-crystal or textured cadmium arsenide films suitable for studying the manifestation of topological properties can be obtained by controlled annealing.

High Sensitivity Low-Temperature Hydrogen Sensors Based on SnO2/κ(ε)-Ga2O3:Sn Heterostructure

The structural and gas-sensitive properties of n-N SnO2/κ(ε)-Ga2O3:Sn heterostructures were investigated in detail for the first time. The κ(ε)-Ga2O3:Sn and SnO2 films were grown by the halide vapor phase epitaxy and the high-frequency magnetron sputtering, respectively. The gas sensor response and speed of operation of the structures under H2 exposure exceeded the corresponding values of single κ(ε)-Ga2O3:Sn and SnO2 films within the temperature range of 25–175 °C. Meanwhile, the investigated heterostructures demonstrated a low response to CO, NH3, and CH4 gases and a high response to NO2, even at low concentrations of 100 ppm. The current responses of the SnO2/κ(ε)-Ga2O3:Sn structure to 104 ppm of H2 and 100 ppm of NO2 were 30–47 arb. un. and 3.7 arb. un., correspondingly, at a temperature of 125 °C. The increase in the sensitivity of heterostructures at low temperatures is explained by a rise of the electron concentration and a change of a microrelief of the SnO2 film surface when depositing on κ(ε)-Ga2O3:Sn. The SnO2/κ(ε)-Ga2O3:Sn heterostructures, having high gas sensitivity over a wide operating temperature range, can find application in various fields.

Properties of Coatings Based on Calcium Phosphate and Their Effect on Cytocompatibility and Bioactivity of Titanium Nickelide

Coatings based on calcium phosphate with thicknesses of 0.5 and 2 μm were obtained by high-frequency magnetron sputtering on NiTi substrates in an argon atmosphere. The coating was characterized using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and in vitro cytocompatibility and bioactivity studies. A biphasic coating of tricalcium phosphate (Ca3(PO4)2) and hydroxyapatite (Ca10(PO4)6(OH)2) with a 100% degree of crystallinity was formed on the surface. The layer enriched in calcium, phosphorus, and oxygen was observed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Scanning electron microscopy showed that the surface structure is homogeneous without visible defects. The 2 µm thick coating obtained by sputtering with a deposition time of 4 h and a deposition rate of 0.43 µm/h is uniform, contains the highest amount of the calcium phosphate phase, and is most suitable for the faster growth of cells and accelerated formation of apatite layers. Samples with calcium phosphate coatings do not cause hemolysis and have a low cytotoxicity index. The results of immersion in a solution simulating body fluid show that NiTi with the biphasic coating promotes apatite growth, which is beneficial for biological activity.

Change of Optical Properties of Carbon-Doped Silicon Nanostructures under the Influence of a Pulsed Electron Beam

In the work, porous silicon with observed photoluminescence was made from a p-type silicon substrate doped with boron and crystallographic orientation (100) using the method of electrochemical etching in a solution containing H2(SiF6) (silicon hydrofluoric acid) and ethyl alcohol. Thin carbon films were sprayed by high-frequency magnetron sputtering at room temperature onto the surface of porous silicon. The resulting carbon-doped thin films of porous silicon were irradiated on a pulsed electron booster and comparisons were made with nonirradiated films of porous silicon. To understand the effect of carbon on the properties of porous silicon films samples were analyzed by Raman spectroscopy, spectrophotometry, and scanning probe microscopy (SPM). The results of the SPM showed that the roughness of the samples increases after carbon doping on the surface of porous silicon. Thus, for the first time, experimental results were obtained on the effect of irradiation on carbon-doped porous silicon obtained in a solution containing hydrogen hexafluorosilicate H2(SiF6) and a significant change in its optical properties was shown. The results of the study showed that irradiated samples of carbon-doped porous silicon have better photoluminescence compared to nonirradiated samples.

Investigation of a high-frequency magnetron sputtering system operation modes during copper thin films deposition

The results of studying the radio frequency (RF) magnetron sputtering (MS) operation parameters during copper sputtering are presented. A comparison of the growth rate dependence on power during the operation of MS is made in RF and DC modes. The pressure dependences of the RFMS growth rate and bias target voltage are obtained. The prospect of using RFMS for deposition of smooth coatings is shown.

Thin SiC and Gan-Based Films and Structures: Production and Properties

The article describes the methods for producing thin films and structures based on SiC, GaN and their SiC – AlN and Al – GaN solid solutions, as well as mathematical models of film growth and properties-behavior of the I–V characteristics of heterostructures. Two models were developed for producing thin films and heterostructures based on SiC, GaN and their solid solutions. The first model makes it possible to determine the sputtering coefficient when producing films by high-frequency magnetron sputtering. In the second quantum-mechanical model, the equation for the gap of the mean field of condensate was built and the growth rate of a film on the crystalline substrate was determined. The current-voltage characteristic of the transistor based on the AlGaN / GaN heterosystem was provided. The models for the growth of heterostructure films made it possible to modify the technologies for producing perfect SiC crystals and SiC – AlN solid solutions. It was possible to offer a pilot plant for growing SiC crystals with improved control over the modes of induction high-temperature heating of the growth crucible.

Electrical and optical properties of thin-film bismuth ferrite

The optical and electrical properties of bismuth ferrite thin films obtained by high-frequency magnetron sputtering in an atmosphere of argon and oxygen (80%+20%) has been studied. Investigations of the optical properties have shown that for polycrystalline bismuth ferrite films the optical band gap is ~2.3 eV, which is in the range of given in the literature values. The dependences of the specific electrical conductivity on the magnitude of the electric field has been studied for the synthesized films. It has been established that the electrical conductivity does not depend on the electric field strength up to the value of E=2.1·106 V/m. The experimental results are discussed in terms of the model of charge carrier injection from aluminum electrode into the conduction band of bismuth ferrite. Keywords: electrical conductivity, strong electric fields, optical absorption coefficient, memristor effect.

Study of relaxers distribution in thin layers of amorphous MoTe-=SUB=-2-=/SUB=-

Recently, transition metal dichalcogenides have come into the spotlight after they have been found to become direct semiconductor in the monolayer level. The paper presents the results of the study of the relaxers distribution in layers of amorphous molybdenum ditelluride obtained by high-frequency magnetron sputtering. According to the obtained values of relaxation parameters α and β, the transition from an asymmetric distribution to a symmetric distribution of relaxators at temperature T=283 K can be stated. The existence of maxima on the temperature dependence of relaxation times taumax=f(T) was found, which can be associated with phase transitions in the studied system. Keywords: molybdenum ditelluride, relaxers distribution, thin layers, phase transitions.

Электрические и оптические свойства тонкопленочного феррита висмута

The optical and electrical properties of bismuth ferrite thin films obtained by high-frequency magnetron sputtering in an atmosphere of argon and oxygen (80% + 20%) has been studied. Investigations of the optical properties have shown that for polycrystalline bismuth ferrite films the optical band gap is ~3 eV, which is in the range of given in the literature values. The dependences of the specific electrical conductivity on the magnitude of the electric field has been studied for the synthesized films. It has been established that the electrical conductivity does not depend on the electric field strength up to the value of E = 2.1106 V/m. The experimental results are discussed in terms of the model of charge carrier injection from aluminum electrode into the conduction band of bismuth ferrite.

ОСОБЛИВОСТІ ВИБОРУ ДІЕЛЕКТРИЧНИХ ШАРІВ ДЛЯ ЕЛЕКТРОЛЮМІНЕСЦЕНТНИХ СТРУКТУР

The paper considers an equivalent scheme of a thin-film electroluminescent emitter (TFELE), taking into account dielectric leaks, and proposes a criterion for the optimal choice of a dielectric in the structure to increase its efficiency. A calculation method is proposed for the optimal choice of material for dielectric films in an electroluminescent structure, taking into account their dielectric loss tangent. The algorithm for optimizing the parameters is based on the method of pairwise comparison of two dielectrics, provided that the charge flowing through the structure is constant or increased. The calculated data for materials are given in the form of a table according to the sequence of deterioration of their characteristics. The most attractive of the materials considered are PbTiO3, Ta2O5, Y2O3, as well as improved ceramics, which is confirmed by experiment. The possibility of applying the proposed model to explain the dependence of the luminosity of electroluminescent emitters on their excitation voltage is shown. A comparative analysis of the results of the calculation and experiment of the dependence of brightness on the applied voltage (B-V) for three types of TFELE based on a luminescent layer ZnS : Mn (0.5%) with a thickness of 0.6 μm, placed between two dielectric layers with a thickness of about 0.3- 0.35 μm with Ta2O5, Sm2O3 and Y2O3, respectively. It is established that the threshold luminescence excitation voltage correlates with the value of εE, and the maximum brightness with the value of εE / tg (δ). The table also shows the calculated characteristics of NdAlO3 and AlN films deposited by high-frequency magnetron sputtering. Higher brightness values can be expected from electroluminescent structures with such a dielectric than from structures with dielectric films with Sm2O3 and Y2O3. The results of such studies are presented in the form of a graph and table. This method can find practical application in the development of new materials and technologies for their production.

НИЗЬКОТЕМПЕРАТУРНА ІОННО-ПЛАЗМОВА ТЕХНОЛОГІЯ ОСАДЖЕННЯ НАНОСТРУКТУРОВАНИХ ПЛІВОК НІТРИДУ АЛЮМІНІЮ ТА БОРУ

A low-temperature (substrate heating temperature up to 400 °C) ion-plasma technology for the formation of nanostructured AlN and BN films by the method of high-frequency reactive magnetron sputtering of the corresponding targets has been developed (the modernized installation "Cathode-1M"), which has in its technological cycle the means of physical and chemical modification, which allow to purposefully control the phase composition, surface morphology, size and texture of nanocrystalline films. The possibility of using the method of high-frequency magnetron sputtering for deposition of transparent hexagonal BN films in the nanoscale state on quartz and silicon substrates is shown. Atomic force microscopy (AFM) has shown that AlN films can have an amorphous or polycrystalline surface with grain sizes of approximately 20-100 nm, with the height of the nanoparticles varying from 3 to 10 nm and the degree of surface roughness from 1 to 10 nm. It was found that the dielectric penetration of polycrystalline AlN films decreases from 10 to 3.5 at increased frequencies from 25 Hz to 1 MHz, and the peak tangent of the dielectric loss angle reaches 0.2 at 10 kHz. Such features indicate the existence of spontaneous polarization of dipoles in the obtained AlN films. Interest in dielectric properties in AlN / Si structures it is also due to the fact that there are point defects, such as nitrogen vacancies and silicon atoms, which diffuse from the silicon substrate during synthesis and play an important role in the dielectric properties of AlN during the formation of dipoles. The technology makes it possible, in a single technological cycle, to produce multilayer structures modified for specific functional tasks with specified characteristics necessary for the manufacture of modern electronics, optoelectronics and sensorics devices. It should also be noted that the technology of magnetron sputtering (installation "Cathode-1M") is highly productive, energetically efficient and environmentally friendly in comparison with other known technologies for creating semiconductor structures and allows them to be obtained with minimal changes in the technological cycle.

Microstructure of the coating obtained by magnetron sputtering of a Ni-Cr-B4C composite target

This paper presents data on obtaining a composite coating by radio frequency (RF) magnetron sputtering of a Ni-Cr-B4C composite target in an inert gas (argon) environment. To make the target, Ni-Cr-B4C composite powder was applied to the copper base of the target by detonation gas-thermal spraying. The obtained targets served as a source of coating material during high-frequency magnetron sputtering. This method of coating production ensures the reproducibility of their properties, as well as the uniformity of coating thickness and good adhesion to various target backings.The data of the study of the structure and morphology of the composite coating are presented. The resulting composite coating Ni-B/Cr7C3 with a thickness of 2 microns has a dense homogeneous structure with expressed textured polycrystallinity. The surface of the resulting coating is represented by nanoscale and homogeneous grains. There is no columnar crystal growth in the coating, which has a positive effect, as the columnar structure reduces the mechanical characteristics of the coatings due to faster oxygen diffusion along the grain boundaries. It is established that the combined use of the Ni-B and Cr7C3 binary phases in composite coatings leads to an increase in operational properties.

Influence of the Lanthanum Doping on the Gas Sensing Properties of the Magnetron Sputtered ZnO films for H2O2 Vapor Detection

This study presents the fabrication of a high-performance hydrogen peroxide vapor sensor based on ZnO film doped with different concentration of La using the high-frequency magnetron sputtering method. The responses (Rgas/Rair) of the fabricated sensors were measured at various operating temperature to different concentrations of hydrogen peroxide vapors. Gas sensing tests indicate that the maximum sensitivity was observed for 2 at.% La concentration in ZnO material and sensor exhibit high sensitivity to low concentration of hydrogen peroxide vapor. We expect that in the future, ZnO doped with 2 at.% La sensitive films will be able to be utilized in highly sensitive, real-time hydrogen peroxide vapor sensors.

Optical properties of CdTe thin film obtained by high-frequency magnetron sputtering method

Cadmium telluride (CdTe) thin films relate to AII BVI compounds and show semiconductor behaviour. They present an important research field because of their wide application in various optoelectronic devices. CdTe-based solar cells attract attention since CdTe is characterised by the direct energy bandgap Eg and high absorbance, which makes it an excellent light-absorbing layer of solar cells. Material evaporation in vacuum by using the high-frequency magnetron sputtering method is one of the most advantageous methods for obtaining uniform films. The present work is dedicated to the investigation of the optical properties of CdTe thin film, which is produced on quarts substrate by the high-frequency magnetro sputtering method. The optical transmission, reflectivity, and μ-Raman spectra of the CdTe thin film have been determined. Linearity of the spectral dependence of the coefficient of optical absorption α of CdTe thin film in the coordinates (αhν)2 vs hν indicates for the direct character of optical transitions corresponding to the long-wavelength edge of fundamental absorption. The optical bandgap of the studied CdTe thin film is found to be Eg = 1.53 eV. The peaks of the experimental m-Raman spectra at 121; 139; 142; 167 and 331 cm–1 are attributed to the phonons in crystalline CdTe and Te.

Electric and photoelectric properties of vacuum-deposited ZnO:Al/CdS/p-Cd1−xZnxTe heterojunctions

The study of electric and photoelectric properties of anisotypic ZnO:Al/n-CdS/p-Cd1−xZnxTe heterojunctions made on unannealed and annealed substrates at high temperature (T = 1200 K) under conditions of minimum cadmium vapor pressure. Sequential application of CdS and ZnO:Al films to the surface of unannealed substrates of single-crystal p-Cd1−xZnxTe was performed by high-frequency magnetron sputtering. Based on the C-V-characteristics analysis, the main parameters of the barrier region of the obtained structures ZnO:Al/n-CdS/p-Cd1−xZnxTe have been determined and the dynamics of their change when irradiated with light of different wavelengths had been established. A relationship between physical processes that lead to a decrease in the concentration of deep levels in the n-CdS/p-Cd1−xZnxTe interface and the properties of the base material has been established.

Cobalt Doped SnO2 Thin Film for Detection of Vapor Phase Hydrogen Peroxide

A technology was developed for manufacturing solid-state semiconductor sensor sensitive to hydrogen peroxide vapors. Gas sensitive nanostructured films made of doped metal oxide SnO2<Co> were manufactured by the high-frequency magnetron sputtering method. The chemical composition of prepared SnO2<Co> targets was analyzed and the thickness of the deposited doped metal oxide film was measured. The morphology of the deposited Co-doped SnO2 film was studied by scanning electron microscopy. The gas sensing characteristics to the different concentrations of hydrogen peroxide vapors at various operating temperatures were also studied. The Co-doped SnO2 sensor showed enough sensitivity to very low concentration of hydrogen peroxide vapors (875 ppb) at the operating temperature of 100 °C. The SnO2<Co> based sensor can be successfully used in medical diagnostic apparatus for determining low concentration of hydrogen peroxide vapors in exhaled air.

Thermal Stability of the Structure and Optical Properties of Nanostructured TIO2 Films

The structure and optical properties of titanium dioxide films have been studied during annealing from 100 to 400°C. The films were obtained by ion-plasma high-frequency magnetron sputtering of polycrystalline rutile target in an argon atmosphere. It was shown that as-prepared TiO2 films are nanostructured with ~8 nm rutile crystallites and ~3.3 A interplanar distances and contain a small fraction of anatase. The optical band gap of the films is 3.01 eV, and the refractive index under normal conditions is 2.25. The film annealing at tamperatures from 100 to 400°C does not practically change their structure, optical band gap, and refractive index under normal conditions, i.e., the obtained nanostructured TiO2 films are thermally stable.