Solid Solution Films Research Articles

Nanoindentation of AlGaN Films Formed on SiC/Si Substrates Grown by the Method of Coordinated Substitution of Atoms

In this article, the mechanical and deformation characteristics of epitaxial films of AlGaN solid solutions formed on silicon substrates of crystallographic orientations (001), (011) and (111) with a silicon carbide (SiC/Si) buffer layer synthesized by the method of the coordinated substitution of atoms were studied using the nanoindentation method. The growth of AlGaN epitaxial layers were carried out both directly on the SiC/Si hybrid substrate and on the SiC/Si substrate additionally coated with an AlN buffer layer. The morphology and structure of the surface of the layers was studied by atomic force microscopy. The structural characteristics of hybrid AlGaN substrates and films grown with and without an aluminum nitride buffer layer were measured. An unambiguous relationship has been established between the mechanical properties (elasticity modulus and hardness) and the surface structure of AlGaN films. It has been found that the AlN buffer layer has a significant effect on the mechanical and deformation properties of AlGaN films at the initial moment of indentation, when the layer is predominantly elastically deformed. The roughness was determined and the surface morphology of the AlGaN films was characterized. For the first time, experimentally, using the nanoindentation method, the hardness parameters and the reduced modulus of elasticity of epitaxial AlGaN grown on hybrid SiC/Si and AlN/SiC/Si substrates were measured.

Explosive crystallization of amorphous germanium-tin films by irradiation with a 3-keV electron beam

Much effort has been expended to obtain thin films of metastable solid solutions of germanium (Ge) that contain as high tin (Sn) content as possible because of their excellent electronic and optoelectronic properties. On the basis of our previous study on amorphous Ge, we demonstrated in this study that irradiation of substrate-free films of amorphous Ge100−xSnx (x = 8, 11, and 19 at. %) with a low-energy electron beam of 3 keV at ambient temperature can induce instantaneous wide-area crystallization (explosive crystallization). Characteristic spiral crystal growth associated with explosive crystallization occurred with areas exceeding 50 μm in diameter around a scanned area of the electron beam of 8 × 8 μm2. As a result, solid solutions of GeSn with Sn concentration up to 19 at. % were obtained with the suppression of precipitation of β-Sn. The region of explosive crystallization reduced in size with increasing Sn content. In addition, thermal analyses revealed that the heat released during crystallization of amorphous GeSn films decreased with increasing Sn content. This relationship indicates that the heat release at the growth front plays a key role in the propagation of explosive crystallization of a-GeSn.

Self-organized vertical multilayer structures in spinodally decomposed TiO2-VO2 films on glass substrates

In this study, we investigated the formation of vertical multilayer structures via phase separation in TiO2-VO2 films on glass substrates. A key point for the formation is to utilize the anisotropy in the spinodal decomposition of the system. Solid-solution films of Ti0.3V0.7O2 were grown on quartz glass substrates using pulsed laser deposition and annealed inside the spinodal region. X-ray diffraction, scanning transmission electron microscopy (STEM) measurements showed that spinodal decomposition occurs along the c-axis, and multilayer structures composed of alternating stacking of Ti- and V-rich phases were formed in the annealed film. In addition, STEM observations revealed that the multilayer structures were aligned vertically on the surface to the glass substrates. In resistivity measurements the annealed film showed a metal-insulator transition with the transition temperature lower than TixV1-xO2 bulk due to the strain effect induced by the coherent interface between Ti- and V-rich phases. The overall results clearly show that vertical multilayer structures were formed via spinodal decomposition along the c-axis direction in the Ti0.3V0.7O2 film on the glass substrates. Our study indicates that anisotropy in the spinodal decomposition is an effective approach for the formation of self-organized vertical multilayer structures in Ti0.3V0.7O2 films on glass substrates, and provides useful guidelines for generating self-organized novel nanostructures on amorphous substrates in oxide films.

Formation Mechanism and Bandgap Reduction of GaN-ZnO Solid Solution Thin Films Fabricated by Nanolamination of Atomic Layer Deposition.

Nanolamination of GaN and ZnO layers by atomic layer deposition (ALD) is employed to fabricate GaN-ZnO homogeneous solid solution thin films because it offers more precise control of the stoichiometry. By varying the ALD cycle ratios of GaN:ZnO from 5:10 to 10:5, the (GaN)1- x (ZnO)x films with 0.39≦x≦0.79 are obtained. The formation of solid solution is explained based on the atomic stacking and preferred orientation of the layers of GaN and ZnO. However, the growth rates of GaN and ZnO during the lamination process are different from those of pure GaN and ZnO films. It is found that GaN grows faster on ZnO, whereas ZnO grows slower on GaN. The density function theory (DFT) calculations are performed using a superlattice model for GaN and ZnO laminated layers fabricated by ALD to understand the difference of density of states (DOS) and evaluate the bandgaps for various atomic configurations in the solid solution films. The band positions are experimentally defined by ultraviolet photoelectron spectroscopy. Significant bandgap reduction of the solid solutions is observed, which can be explained by the DOS from the DFT calculations. Visible-light-driven photocatalytic hydrogen evolution is conducted to confirm the applicability of the solid solution films. This article is protected by copyright. All rights reserved.

Processes of Current Transport in p-Si-n-(Si<sub>2</sub>)<sub>1−</sub><i><sub>y</sub></i><sub>−</sub><i><sub>z</sub></i>(GaP)<i><sub>y</sub></i>(ZnSe)<i><sub>z</sub></i> Heterostructure Produced by Liquid Phase Epitaxy

The possibility of growing multicomponent epitaxial films of a semiconductor solid solution of molecular substitution (Si2)1−y−z(GaP)y(ZnSe)z on Si and GaP substrates by liquid-phase epitaxy is shown. The distribution profiles of the atoms of the solid solution components Ga, P, Zn, Se, and Si over the thickness of the epitaxial film have been determined. The current-voltage (I−V) characteristics of p-Si-n-(Si2)1−y−z(GaP)y(ZnSe)z heterostructures have been studied. A temperature-independent I−V characteristic has been found, the existence of which is explained on the basis of a theory considering the possibility of "blurring" of the impurity level. By comparing the theoretical and experimental results, the half-width of the blurring band for the energy levels of atoms of Si2 and GaP molecules was determined, which had values equal to 0.146 and 0.34 eV, respectively.

Structural features of Cu2MgxZn1−xSnS4 solid solution films for third-generation solar cells

The paper studies the influence of the ratio of Mg/Zn molar concentrations in the precursor (0 ≤ y ≤ 0.5) on the structural, substructural, optical characteristics and chemical composition of Cu2MgxZn1−xSnS4 films deposited by the spray pyrolysis method from molecular solutions. The data of X-ray structural studies indicate the formation of single-phase films with the structure of kesterite. The single-phase structure is also confirmed by studies of Raman spectra for samples obtained at y ≤ 0.3. Chemical analysis of the films confirms the successful inclusion of Mg in thin layers up to the level of (5.5–6.7) at%. An increase in the total amount of Mg has little effect on the concentration of all elements except zinc. The introduction of magnesium changes the lattice constants of the material, the sizes of coherent scattering regions, the level of microdeformations, and the density of dislocations in the films. At the same time, the layers obtained at y = 0.1 have the minimum total concentration of dislocations (0.73·1017 lin/m−2). Thus, replacing zinc with magnesium increases the quality of the solid solution at concentrations y < 0.3. The band gap of the undoped Mg compound was found to be 1.47 eV, and for the Mg-doped samples it decreases from 1.28 eV (y = 0.1) to 1.22 eV (y = 0.5). Thus, based on the obtained results, the Cu2MgxZn1−xSnS4 solid solution can be considered as an inexpensive material for creating absorption layers of thin-film solar cells.

Mid-infrared complex permittivity in Bi2-Sb Te3-Se thin films synthesized using a combinatorial method

• A combinatorial material library of Bi 2- x Sb x Te 3- y Se y thin films was synthesized. • λ c shifts from 5.346 μm for Bi 2 Se 3 to 9.232 μm for Sb 2 Te 3 . • The compositionally adjustable mid-infrared plasmonic property was carried out. Successful employment of plasmonics-inspired solutions in the mid-infrared frequency range would benefit a number of highly important technologies. As a plasmonic material beyond gold and silver, Bi-based chalcogenide semiconductor alloys exhibit a wide tunability in the spectral dispersion of relative permittivity by varying the composition of their ternary and quaternary compounds. In our investigation, a combinatorial materials library of Bi 2- x Sb x Te 3- y Se y thin films were synthesized. The complete solid solubility and the in-depth chemical composition profile of thin film pixels in the library were confirmed using micro-area X-ray diffraction and secondary ion mass spectroscopy, respectively. The stoichiometries of thin film pixels were acquired using the energy dispersive X-ray analysis. The mid-infrared spectral transmittance was measured using a Fourier-transform infrared spectrometer. The complex permittivity ε ( ω ) in the spectral range from 2.5 to 15 μm was derived by fitting spectral transmittance to the Drude–Lorentz equation. It can be demonstrated that the negative values of real part of permittivity, ε r , emerge at the shorter wavelengths. The crossover wavelength, at which ε r crosses zero from negative to positive, can shift from 5.346 μm for Bi 2 Se 3 to 9.232 μm for Sb 2 Te 3 with the increasing of x and the deceasing of y . Therefore, an exceptionally wide and potentially interesting mid-infrared plasmonic property, which is compositionally adjustable, can be carried out for evaporation-deposited Bi 2- x Sb x Te 3- y Se y solid-solution thin films.

Microstructure and resistivity of Au-B supersaturated solid-solution films prepared by sputter deposition

• A series of Au–B films was deposited by magnetron sputtering. • Au-B supersaturated solid solutions without AuB 2 compounds confirmed in the films. • The microstructure of the Au–B supersaturated solid-solution films was studied. • The relationship between the resistivity and b content in the films was revealed. • The Au–B supersaturated solid-solution films were stable at room temperature. Au-B films are of interest for superconductor and hohlraums materials. A series of gold-boron (Au-B) films with different B contents has been deposited by magnetron sputtering of Au-B pseudo-alloy targets in an Ar atmosphere. The B atomic concentration of the Au-B films was varied by adjusting the B contents of the Au-B targets and sputtering pressure. The composition, microstructure and resistivity of the Au-B films were investigated by X-ray photoelectron spectrometry, X-ray diffraction and the four-probe method. Due to the mutually immiscibility of Au and B, non-equilibrium supersaturated solid solutions of B in Au with nanocrystalline microstructures instead of AuB 2 metal diboride were observed in the as-deposited films. With increasing B content, the average grain size of the films decreased and the d -spacing of Au (111) increased. The resistivity of the Au-B supersaturated solid-solution films was linearly related to the B content and no superconductivity was observed. The structure of the Au-B films was stable at room temperature for a long time, while annealing caused phase transition.

Composition dependence of ferroelectric properties in (111)-oriented epitaxial HfO2-CeO2 solid solution films

The composition dependence of ferroelectric properties was investigated for (111)-oriented epitaxial HfO2-CeO2 solid solution films. Twenty nanometer thick films with different compositions were prepared on (111)ITO//(111)YSZ substrates at room temperature by pulsed laser deposition and subsequent heat treatment at 1000 °C under atmospheric N2 or O2 gas flow. All the films had fluorite structures, and their crystal symmetries changed from monoclinic through orthorhombic to tetragonal/cubic phases as x increased for the (Hf1−x Ce x )O2 (x = 0.12–0.25) films. The orthorhombic phase was confirmed by X-ray diffraction analysis for films with x = 0.15 and 0.17. On the other hand, ferroelectric properties were observed in films with x = 0.15–0.20, suggesting that a field-induced phase transition takes place for films with x = 0.20. The film composition showing ferroelectricity was the widest range of doping concentration for reported epitaxial HfO2-based films. Their remanent polarization (P r) and coercive field (E c) were almost identical, at 17–19 μC cm−2 and 2.0–3.0 MV cm−1. This wide ferroelectric composition range with relatively similar ferroelectricity is due to the solid solution of the same fluorite structure of HfO2 and CeO2 with monoclinic and cubic symmetries, that are respectively lower and higher crystal symmetries of the ferroelectric orthorhombic phase.

FEATURES OF THE ELECTRICAL PROPERTIES OF HETEROJUNCTIONS N-GAAS-P-(GAAS)1 - X - У(GE2)X(ZNSE)Y

The optimal technological conditions for growing multicomponent epitaxial films of solid solutions (GaAs)1 - x - y(Ge2)x(ZnSe)y with specified physical properties by liquid-phase epitaxy have been determined. It has been established that the above conditions for growing thin films from a tin solution-melt at temperature intervals of 730-630, 650-550 °С with a substrate cooling rate of 1 deg/min are the most optimal. In this case, the films had a thickness of 10 μm and p-type conductivity. For ohmic contacts to such semiconductor solid solutions, Sn, Au, In, (In-Ga) and (Ge-Ag) alloys were used. It was determined that the mobility of current carriers depends on the composition, the structural perfection of the epitaxial layers and the ionization energy of the atoms of the constituent components have values of 0.19, 0.07, 0.029 eV. It has been established that in heterostructures of the n-GaAs-p-(GaAs)1 - x - y(Ge2)x(ZnSe)y type, obtained at Т = 7500 °С, the current transmission is determined by tunneling-recombination, and in the samples obtained at Т = 7300 °С, by currents limited volume charges. It was also determined that a region with a higher resistivity is formed at the heterointerface, the thickness of which, depending on the growth conditions of thin films, is from 0.2 to 0.5 μm.

Electric Tunable Structures Based on BaZr&lt;sub&gt;x&lt;/sub&gt;Ti&lt;sub&gt;1–x &lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and BaSn&lt;sub&gt;x&lt;/sub&gt;Ti&lt;sub&gt;1–x&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Solid Solutions for Microwave Applications

Introduction. An experimental study of the structural and electrophysical properties of multicomponent films of solid solutions of barium titanate-zirconate and barium titanate-stannate on sapphire substrates has been carried out. These materials are an alternative to the more studied barium-strontium titanate for use in microwave technology, due to the relatively high controllability. In this paper, it is shown that when using post-post high-temperature annealing, films with a component composition close to the composition of the sprayed targets are formed on the substrate. Optimal deposition temperatures of thin films of barium titanate-zirconate and barium titanate-stannate have been determined to obtain the best electrophysical parameters.Aim. Investigation of structural and microwave properties of BaZrxTi1-xO3 (BZT) and BaSnxTi1–xO3 (BSnT) films on dielectric substrates. These ferroelectric materials are promising in terms of losses and nonlinearity, and the formation of planar structures based on these materials on a dielectric substrate allows for a significantly higher level of operating power of the microwave device.Materials and methods. The crystal structure and phase composition of the obtained films were studied by X-ray diffraction using a DRON-6 diffractometer on the emission spectral line CuKa1 (λ = 1.5406 Å). Capacitance C and Q-factor (Q = 1/tg δ) of capacitors were measured at frequencies of 1 and 3 GHz using a resonator and an HP 8719C vector analyzer.Results. It is established that high-temperature annealing after film deposition has a significant effect on the crystal structure, phase composition of films and their electrical characteristics. For the first time, a low level of dielectric losses of planar capacitive elements based on titanate-stannate and barium titanate-zirconate films in the frequency range of 1…60 GHz with acceptable controllability has been demonstrated.Conclusion. The results obtained indicate the prospects of using thin ferroelectric films of BaSn0.5Ti0.5O3 and BaZr0.5Ti0.5O3 solid solutions in microwave devices.

Topical Film-Forming Solid Solutions for Enhanced Dermal Delivery of the Retinoid Tazarotene

Topical film-forming solutions (FFSs) show considerable potential for dermal delivery of an API. Through a mechanism of in situ film formation upon solvent evaporation, they may improve skin delivery by prolonging substantivity on the skin, by establishing a transient supersaturation, and/or by enhancing solubility through the formation of a solid dispersion in the resulting film.This work aimed at developing an FFS for topical application with enhanced skin delivery. The tested FFSs were composed of the lipophilic retinoid tazarotene and the hydrophobic polyamide-3 polymers.The residual films cast from FFSs were examined by DSC and their release mechanism was investigated. Additionally, ex vivo skin penetration of tazarotene was explored.In comparison to a physical mixture, the glass transition (Tg) was significantly increased (p < 0.01) in in-situ generated polyamide-3 (11,500 Da)/tazarotene films with ratios 5:1 and 10:1, indicating a molecular distribution of tazarotene within the polymer. Stress testing at 32°C and 40°C further indicated that these films were kinetically stabilized for at least two weeks. Tazarotene release from solid solution films was notably increased as compared to the crystalline and the amorphous tazarotene. A ten-times higher skin penetration of the ratio 10:1 film (containing 0.1% tazarotene) was observed as compared to a commercial 0.1% tazarotene cream.Hence, topical solid solutions may represent an option for improved dermal API delivery.

Strain relaxation and spinodal decomposition in composition adjusted TiO2-VO2 films on TiO2(100) substrates

In this study, we investigate the process of strain relaxation and spinodal decomposition in TiO2-VO2 films on TiO2(100) substrates. Herein, the film composition was adjusted to Ti0.2V0.8O2 for the relaxation of the in-plane tensile c-axis strain in the films. A 115 nm thick Ti0.2V0.8O2 solid-solution film is epitaxially grown on a rutile-type TiO2(100) substrate using a pulsed laser deposition technique, and is annealed inside the spinodal region. Reciprocal space mapping measurements show that the in-plane tensile c-axis strain is almost fully relaxed in the solid-solution film. Scanning transmission electron microscopy (STEM) observation results reveal that the annealed film causes spinodal decomposition along the c-axis direction, forming vertically aligned multilayer structures. The STEM observations also suggest the presence of interfacial misfit dislocations along the c-axis, indicating the generation of plastic strain relaxation along the c-axis in the film. Composition analysis reveals that the Ti-V interdiffusion between the film and substrate is considerably suppressed. The overall results of this study show that the composition adjustment to Ti0.2V0.8O2 is effective for strain relaxation along the in-plane c-axis and occurrence of spinodal decomposition with reduced Ti-V interdiffusion in the TiO2-VO2 films on TiO2(100). Our study helps establish a method for the formation of nanostructures via spinodal decomposition in the TiO2-VO2 films.

Magnetic and Optical Properties of Au-Co Solid Solution and Phase-Separated Thin Films and Nanoparticles.

The chemical composition and morphology of AuxCo1-x thin films and nanoparticles are controlled via a combination of cosputtering, pulsed laser-induced dewetting (PLiD), and annealing, leading to tunable magnetic and optical properties. Regardless of chemical composition, the as-deposited thin films and as-PLiD nanoparticles are found to possess a face-centered cubic (FCC) AuxCo1-x solid-solution crystal structure. Annealing results in large phase-separated grains of Au and Co in both the thin films and nanostructures for all chemical compositions. The magnetic and optical properties are characterized via vibrating sample magnetometry (VSM), ellipsometry, optical transmission spectroscopy, and electron energy loss spectroscopy (EELS). Despite the exceptionally high magnetic anisotropy inherent to Co, the presence of sufficient Au (72 atom %) in the AuxCo1-x solid solution results in superparamagnetic thin films. Among the as-PLiD nanoparticle samples, an increased Co composition leads to a departure from traditional ferromagnetism in favor of wasp-waisted hysteresis caused by magnetic vortices. Phase separation resulting from annealing leads to ferromagnetism for all compositions in both the thin films and nanoparticles. The optical properties of AuxCo1-x nanostructures are also largely influenced by the chemical morphology, where the AuxCo1-x intermixed solid solution has significantly damped plasmonic performance relative to pure Au and comparable to pure Co. Phase separation greatly enhances the quality factor, optical absorption, and electron energy loss spectroscopy (EELS) signatures. The enhancement of the localized surface plasmon resonances (LSPRs) scales with the reduction in Co composition, despite EELS evidence that excitation of the Co portions of a nanoparticle can provide a similar, and in some instances enhanced, LSPR resonance compared to Au. This behavior, however, is seemingly limited to the LSPR dipole mode, while higher-order modes are greatly damped by a Co aloof position. This observed magneto-plasmonic functionality and tunability could be applicable in biomedicine, namely, cancer therapeutics.

Block and single-crystal films of bismuth-antimony alloy 3-12 at.% with an underlayer of antimony

The influence of an antimony sublayer (10 nm) on the structure and galvanomagnetic properties of thin films of a bismuth-antimony solid solution (3-12 at.% Sb) up to 1 μm thick has been studied. The films were produced on mica substrates by discrete vacuum evaporation and zone recrystallization. We found that the misorientation of the crystallite plane (111) increases relative to the film plane as well as the crystallite sizes decrease. The antimony underlayer does not change the crystallographic orientation during recrystallization and increases the film adhesion. The change in the galvanomagnetic coefficients when using a sublayer is due to the classical dimensional effect and increasing plane deformation. Keywords: bismuth, antimony, thin film, antimony underlayer, single-crystal film, atomic force microscopy

Enhanced photovoltaic effect derived from the regulation of Jahn–Teller distortion in a lattice compensation structure

Larger remanent polarization and lower optical bandgap play crucial roles in the ferroelectric photovoltaic effect. However, they are always mutually conditioning for almost perovskite material based orbital hybridization theories. Here, we design a lattice compensation structure, in which Eu was incorporated to strengthen J–T distortion of Mn–O octahedral in BiFeO3–BiMnO3 solid solution films due to relieved degeneracy; in turn, the distortion compensates the lattice shrink derived from Eu doping. A narrow bandgap of 2.24 eV and a large remanent polarization of 93.7 μC/cm2 are achieved by lattice compensation modification. Compared with the film with an Eu doping concentration of 0.04, the open-circuit voltage and the short-circuit current of the film with 0.08 doping concentration are increased by 4.6 and 2.7 times, respectively, showing remarkable ferroelectric photovoltaic response. This work identifies an alternative strategy to enhance ferroelectric photovoltaic effects by regulating J–T distortion and lattice compensation.

A Brief Review on the Ferroelectric Fluorite-Structured Nanolaminate

Ferroelectricity can be induced in fluorite-structured oxides such as HfO2 and ZrO2, a feature of increasing interest in both academia and industry. Initially, most research focused on solid solution films, but recently, it has been suggested that nanolaminates with independent HfO2 and ZrO2 layers may show electrical and physical properties superior to those of solid solution samples. It was reported that the nanolaminate samples could have remanent polarization higher than that of solid solution film or a wider composition window for robust ferroelectricity compared to the solid solution films. In this review, the existing literature on fluorite-structured nanolaminates is comprehensively reviewed.

Novel production techniques for solid solution Nb–Y–N films with improved tribological properties and hydrophobic behavior

NbN is extensively used in precision machining applications from cutting tools to anti-scratch films due to its high hardness, high melting point, and good chemical inertness. However, in order to extend its application scenarios, such as friction and erosion, a novel hard NbN-based film need to be designed with high hydrophobicity and low friction to prolong the service life of the machine. Here, this work proposed a novel strategy to form the Nb–Y–N solid solution film by adding a small amount of Y into the NbN sublattice via magnetron sputtering. It is found that the doping of different content Y into NbN would affect both its wettability and tribological behavior. The final experimental results show that a few Y atoms incorporated can lead to a transformation from hydrophilic to hydrophobic for the NbN. Furthermore, the results from Raman spectroscopy and Scanning Electron Microscopy-Energy Dispersive Spectrometry confirm that the formation of yttrium oxide on Nb–Y–N solute solution film produced by surface oxidation has a very important role in improving both friction performance and hydrophobicity. Besides, the introduction of solute Y can increase the wear resistance and hardness of the NbN, which has considerable application potential for optimizing the comprehensive performance of NbN film.

Controlling preferential growth of chromium – Nitrogen R-HiPIMS and R-DCMS films by substrate magnetic biasing

The effect of magnetic biasing on the structure of Cr-N coatings deposited on silicon substrates by reactive magnetron sputtering has been investigated. The magnetic biasing setup consisted of a permanent magnet placed close to the substrate holder to modify the plasma species dynamics and deposition flux. Three magnetic field configurations for reactive direct current magnetron sputtering (R-DCMS) and reactive High Power Impulse Magnetron Sputtering (R-HiPIMS) were compared. Deposition parameters such as deposition time, gun power, substrate distance, temperature, gas pressure, and gas composition were constant through the six R-DCMS/HiPIMS-magnetic-field combinations. Processes were monitored through optical emission spectroscopy (OES) and closely compared to the voltage and current curves at the target/substrate. An excitation mechanism was proposed accounting for the enhanced ionization detected by OES and the implications in the film’s growth. The films’ stoichiometry, structure, thickness, morphology, and crystal texture were characterized and associated with the process parameters. The R-DCMS processes led to Cr-N solid solution films, while the enhanced reactivity of R-HiPIMS plasma species increased the N content and formed CrN. Overall, the R-DCMS deposited samples were thicker than the R-HiPIMS deposited samples, but the different magnetic field biasing setups allowed for specific control of films’ thickness, texture, and microstructure.

Sputter-deposited TaCuN films: Structure, tribological and biomedical properties

Stainless steel is a material that is commonly used in brackets and arch wires during orthodontic treatment. However, the high frictional resistance that occurs between stainless steel/stainless steel can reduce the efficiency of orthodontics. Developing protective films is a simple and effective method that can produce low friction in saliva environment. In this study, we investigated the respective mechanical and tribological behaviors of pure TaN film, TaCuN solid solution film and TaN/Cu nanocomposite film. Hardness tests showed that the hardness of TaN and TaN/Cu are approximately 15.6 and 7.3 GPa, respectively. However, TaCuN film has a higher hardness of about 17.6 GPa, which contributes to its excellent wear resistance. The hydrolysis reaction of TaCuN film during friction process turns the saliva environment into a solution containing oxide colloid particles. Moreover, during friction, a Cu2O-induced hydrophobic surface appears. As a result of the colloidal solution with double electric layer repulsion generated by this process and the saliva-lubricating film absorption of the hydrophobic surface, the TaCuN film achieves outstanding tribological properties, with a friction coefficient and wear rate of 0.045 and 1.18 × 10-9 mm3/Nm, respectively. In addition, biological experiments confirm that the TaCuN film is a material with non-toxic and good biocompatibility and that it demonstrates stronger antibacterial ability than stainless steel. Depositing the TaCuN solid-solution film on the arch wires represents an effective approach for the surface modification of orthodontic appliances. Furthermore, TaCuN film could potentially be applied as a protective film in the field of dental treatment.