CrN Thin Films Research Articles

EFFECTS OF BIAS VOLTAGES ON ADHESION AND PROPERTIES OF CHROMIUM NITRIDE THIN FILMS

Thin films were deposited on SUS440 stainless steel samples by arc plasma evaporation at substrate bias voltages of 10–100 V. X-ray diffraction, optical microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, microhardness test, and electrochemical test were used to investigate the morphology and properties of the thin films. Particularly, the thin films were composed of chromium nitride (CrN, phases of CrN + Cr) and 0.76 mm thick. They were deposited with microdroplets on the samples. The surface hardness of these films reached the highest value of 1492 HV at the bias of 20 V. As the bias voltage increased, the adhesion of the CrN thin films decreased. The excessively high bias voltage of 100 V led to the delamination of the CrN thin films. The electrochemical test demonstrated that the corrosion resistance in the 3% NaCl solution of CrN coating can be improved.

Investigation of Pressure Effect on Structural, Mechanical Properties and Corrosion Performance of CrN Thin Films

Properties (crystallographer, mechanical and anti-corrosion) of deposited chromium nitride thin films on Silicon (100) and stainless steel (SS 304) substrates, in a direct current (DC) magnetron sputtering without annealing the substrates; have been investigated as a function of working pressure. It was observed that pressure increase induced crystallization enhancement, thickness decrease, and grain size increase and micro-hardness decrease. The corrosion resistance of the films, using the electrochemical impedance spectroscopy (EIS) technique in the water solution at 50 °C, was found to decrease with pressure increase, where the film deposited at 4 mTorr, having the highest micro-hardness, showed the best corrosion behavior. The surface morphology was investigated by optical microscope before and after the corrosion.

Hardness of chromium nitride thin films prepared with addition of ytterbium

In this work, Yb was added as a third element to CrN as a means of developing new hard coatings materials via solution hardening. Cr–Yb–N thin films were prepared on Si substrates by pulsed laser deposition with various Yb contents, and compositional analysis confirmed that these films contained the expected elements. Phase identification results showed that the Cr1−xYbxN thin films for x ≤ 0.23 consisted of YbN in CrN as a solid solution with B1-(Cr,Yb)N as the only phase. However, films having x values of 0.51 or 0.53 had a two phase structure comprising (Cr,Yb)N and YbN. The hardness of each Cr–Yb–N thin film was successfully improved compared to that of a pure CrN thin film.

Effect of the period of the substrate oscillation in the dynamic glancing angle deposition technique: A columnar periodic nanostructure formation

Nanostructured CrN thin films are obtained by combining RF physical vapor and dynamic glancing angle deposition using a computer-controlled substrate oscillatory motion. By using an appropriate frequency for substrate oscillation, it becomes feasible to tailor the physical properties of thin films deposited onto the substrate. The films are deposited by moving the substrate back and forward between specified angles with, among other parameters, a controlled time-dependent angular position φ(t) of the substrate. Thus, the direction of atoms striking the film changes in accordance to the position of the substrate.In this paper, we report the physical properties of a material for a varying frequency of substrate oscillation while maintaining the same angular φ(t) function (triangular function) in all the studied samples. By controlling the incidence angle φ(t) for precursor atoms impinging upon the substrate, one can prompt the formation of wavy-like periodic columnar nanostructures. The physical characteristics of the coating such as morphology, residual stress, nanohardness, crystallite size, composition, and texture of the columnar periodic multistructured films are all remarkably dependent on the oscillation frequency. The cited physical properties obtained by moving the substrate forward and back with an angular φ(t) triangular function and several periods of oscillation are reported and analyzed.

Combination of an atmospheric pressured arc reactor and a magnetron sputter device for the synthesis of novel nanostructured thin films

Nanocomposite coatings are state of the art, nevertheless the possible material combinations are restricted. Therefore, this work demonstrates an approach to synthesize novel nanostructured thin films by producing the nanoparticles and thin films independently. An atmospheric-pressure transferred arc reactor is used to synthesize TiN nanoparticles. The device is linked to a magnetron sputter device with an aerodynamic lens system. The aerodynamic lens enables the in-situ introduction of the synthesized nanoparticles into the PVD chamber by compensating the pressure differences. In this study, the influence of the linkage on the properties of a CrN thin film as well as the chamber conditions (pressure, temperature, bias-voltage, and plasma) on the TiN nanoparticles are analyzed. The CrN thin film is only slightly affected by the incoming working gas of the nanoparticle reactor. The TiN nanoparticles reveal a crystallite size of 9.3 ± 2.3 nm and are successfully introduced into the PVD chamber as agglomerates with sizes of 0.04 μm2 and are then deposited onto substrates. It is shown that the particle distribution, agglomerate size, morphology, and crack behavior can be influenced by the chamber conditions.

Nanostructured porous CrN thin films by oblique angle magnetron sputtering for symmetric supercapacitors

Transition metal nitrides become promising electrode materials for supercapacitors due to high chemical stability and electrical conductivity. This study reports a facile (one step) and green (mixed atmosphere of argon and nitrogen without any external heating) strategy for fabricating nanostructured porous transition metal nitride thin films by oblique angle magnetron sputtering and their applications as binder-free electrode materials for symmetric supercapacitors. Using CrN as a demonstration, the thin film electrode shows a high specific capacitance of 17.7 mF cm−2 at a current density of 1.0 mA cm−2, exceeding most of previously reported transition metal nitrides by normal magnetron sputtering. Furthermore, a symmetric supercapacitor device based on nanostructured porous CrN thin film can deliver maximum energy and power densities of 7.4 mWh cm−3 and 18.2 W cm−3 respectively, along with good cycling stability (92.2% capacitance retention after 20000 cycles at a current density of 2.0 mA cm−2). Specially, the oblique angle magnetron sputtering can serve as a versatile route to fabricate nanostructured porous transition metal nitrides for electrochemical energy storage and conversion.

Structure and Oxidation Behavior CrN Thin Films Deposited Using DC Reactive Magnetron Sputtering

The CrN ceramic thin films were deposited using DC reactive magnetron sputtering system on silicon wafer substrate. Oxidation behavior was carried out in air at evaluated temperatures ranging from 500 °C up to 900 °C for 2 h. The structure and element composition of the films at different thermal annealing temperatures ranging were investigated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), respectively. The oxidation activation energies of the films were calculated using Arrhenius equation. The changes in the crystal structure from CrN to Cr2O3 phase were investigated from XRD results. The accumulation of grains on surface was confirmed by FESEM micrographs. The cross-section analysis showed an apparent columnar feature with dense structure for the film annealed at low temperature, and becomes porous when increasing the annealing temperature. The thickness was increased from 1.43 to 2.67 μm. The EDS studies indicated the existence of Cr, N and O with different elements compositions on the deposited thin films. The oxidation activation energy for the CrN thin films is 124.4 kJ/mol.

The effect of duplex surface treatment on erosion performance of QRO 90 Supreme steel

In this study, CrN and TiAlN thin films were deposited on plasma-nitrided QRO 90 Supreme hot work tool steel by physical vapor deposition process and analysed with regard to their erosion performance under hydro-abrasive erosion conditions. The as-received specimens were quenched to room temperature from 1050°C and tempered gradually at 605°C for 2 h and at 560°C for 4 h. These specimens were plasma-nitrided for 10 h at 500°C at a pressure of 250 Pa in a gas mixture of 80% N2 + 20% H2 and then coated with TiAlN or CrN coatings by cathode arc evaporation. The specimens were characterized by metallographic techniques, SEM, EDS and micro-hardness test. Plasma nitriding and duplex surface treatments significantly increased the hardness of the specimens and thus significantly reduced the erosion of the specimens. The hardnesses on the surface of plasma-nitrided, CrN-deposited and TiAlN-deposited QRO 90 steels were 1092 HV0.025, 2436 HV0.025 and 3578 HV0.025, respectively. TiAlN-coated specimens were about 17-fold harder than the as-received specimens and over 3-fold harder than the plasma-nitrided specimens. The erosion resistance of CrN-coated specimens was increased by a factor of 3.6 and 1.5 compared with that of the as-received and plasma-nitrided specimens, respectively. A brittle fracture phenomenon was observed on the eroded surface of the duplex-treated specimens while a ductile material removal was observed on the as-received and the tempered specimens. The plasma-nitrided specimens showed a mixed behaviour of ductility and brittleness.

Microstructure and thermoelectric properties of CrN and CrN/Cr2N thin films

CrN thin films with an N/Cr ratio of 95% were deposited by reactive magnetron sputtering onto (0 0 0 1) sapphire substrates. X-ray diffraction and pole figure texture analysis show CrN (1 1 1) epitaxial growth in a twin domain fashion. By changing the nitrogen versus argon gas flow mixture and the deposition temperature, thin films with different surface morphologies ranging from grainy rough textures to flat and smooth films were prepared. These parameters can also affect the CrNx system, with the film compound changing between semiconducting CrN and metallic Cr2N through the regulation of the nitrogen content of the gas flow and the deposition temperature at a constant deposition pressure. Thermoelectric measurements (electrical resistivity and Seebeck coefficient), scanning electron microscopy, and transmission electron microscopy imaging confirm the changing electrical resistivity between 0.75 and 300 , the changing Seebeck coefficient values between 140 and 230 , and the differences in surface morphology and microstructure as higher temperatures result in lower electrical resistivity while gas flow mixtures with higher nitrogen content result in single phase cubic CrN.

Structure and magnetic properties of CrN thin films on La0.67Sr0.33MnO3

High crystalline quality CrN thin films have been grown on La0.67Sr0.33MnO3 (LSMO) templates by molecular beam epitaxy. The structure and magnetic properties of CrN/LSMO heterojunctions are investigated combining with the experiments and the first-principles simulation. The Nėel temperature of the CrN/LSMO samples is found to be 281 K and the saturation magnetization of CrN/LSMO increases compared to that of LSMO templates. The magnetic property of CrN/LSMO heterostructures mainly comes from Cr atoms of (001) CrN and Mn atoms of (001) LSMO. The (001) LSMO induces and couples the spin of the CrN sublattice at CrN/LSMO interface.

Properties of CrN thin films deposited in plasma-activated ABS by reactive magnetron sputtering

In this work, magnetron sputtered CrNx thin films with nitrogen concentrations ranging from 17 to 30at.% were deposited on plasma activated ABS. Two sets of thin films were obtained by varying the N2 flow inside the vacuum chamber (series #1) and the deposition time (series #2). The polymer samples were also subjected to plasma treatment in Ar prior to the CrNx thin films' deposition, in order to enhance the adhesion. The fundamental microstructural, chemical and physical properties, as well as the electrochemical and adhesion behavior of the CrNx thin films, were assessed by SEM, XRD, 3D profilometry, RAMAN, colorimetry, OCP measurements and cross-cut tape test. Main results show that high-quality CrNx films with a low percentage of defects were obtained. The CrNx film sputtered with 3sccm N2 for 20min was considered to possess the most appropriate brightness, color, electrochemical stability and interfacial adhesion to fit the end-user requirements. Magnetron sputtering is thus a promising alternative to the hazardous chrome plating for an effective metallization of ABS.

Porous CrN thin films by selectively etching CrCuN for symmetric supercapacitors

Transition metal nitrides are regarded as a new class of excellent electrode materials for high-performance supercapacitors due to their superior chemical stability and excellent electrical conductivity. We synthesize successfully the porous CrN thin films for binder-free supercapacitor electrodes by reactive magnetron co-sputtering and selective chemical etching. The porous CrN thin film electrodes exhibit high-capacitance performance (31.3 mF cm−2 at 1.0 mA cm−2) and reasonable cycling stability (94% retention after 20000 cycles). Moreover, the specific capacitance is more than two-fold higher than that of the CrN thin film electrodes in previous work. In addition, a symmetric supercapacitor device with a maximum energy density of 14.4 mWh cm−3 and a maximum power density of 6.6 W cm−3 is achieved. These findings demonstrate that the porous CrN thin films will have potential applications in supercapacitors.

Sputter deposited chromium nitride thin electrodes for supercapacitor applications

Transition metal nitrides have attracted significant attention for energy storage applications due to their unique structural, electronic and catalytic properties. In this study, chromium nitride thin films have been deposited on 304L steel substrate by reactive magnetron DC sputtering and then it used as a supercapacitor electrode without additional processing. These films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray analysis (EDAX, Oxford Instruments), and X-ray photoelectron spectroscopy (XPS) techniques. XRD spectra shows the (1 1 1), (2 0 0), and (2 2 0) planes of the cubic phase of CrN film. The Raman spectra of CrN thin film shows the acoustic vibrational mode at 238 cm−1, and optical mode at 619 cm−1. The FE-SEM images show the columnar structure of CrN thin films. The electrochemical properties were evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The working electrode showed remarkably high specific capacitance of 41.6 F/g at the scan rate of 5 mV/s. The working electrode depicted high capacitance retention of 87% up to 2000 cycles. The electrochemical performance of the CrN showed that they can be used as potential electrode material for electrochemical supercapacitors.

Structural, morphological, and optical characterizations of Mo, CrN and Mo:CrN sputtered coatings for potential solar selective applications

Mo, CrN, and Mo:CrN sputtered coatings synthesized onto silicon Si(100) substrates were investigated as solar selective surfaces and their potential applications in optical devices. These coatings were characterized using XRD, SEM, UV-vis, and FTIR techniques. XRD investigation, showed a change in CrN thin film crystallite characteristic due to Mo doping. Compared to the CrN coating, the Mo:CrN film has a higher lattice parameter and lower grain size of 4.19 nm and 106.18 nm, respectively. FESEM morphology confirmed the decrement in Mo:CrN crystal size due to Mo doping. Optical analysis showed that in the visible range of the solar spectrum, the CrN coatings exhibit the highest solar absorptance of 66% while the lowest thermal emittance value of 5.67 was recorded for the CrN coating doped with Mo. Consequently, the highest solar selectivity of 9.6, and the energy band-gap of 2.88 eV were achieved with the Mo-doped CrN coatings. Various optical coefficients such as optical absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constants, and energy loss functions of these coatings were also estimated from the optical reflectance data recorded in the wavelength range of 190–2300 nm.

Correlation between damage evolution, structural and optical properties of Xe implanted CrN thin films

Polycrystalline CrN thin films were irradiated with Xe ions. The irradiation-induced modifications on structural and optical properties of the films were investigated. The CrN films were deposited on Si(100) wafers with the thickness of 280 nm, by using DC reactive sputtering. After deposition, the films were implanted at room temperature with 400 keV Xe ions with the fluences of 5-20?1015 ions/cm2. The films were then annealed at 700 ?C in vacuum for 2 h. The combination of Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) was used for structural analyses, while changes in optical properties were monitored by spectroscopic ellipsometry. We also measured the electrical resistivity of the samples using a four point probe method. RBS analysis reveals that the concentration of Xe in the layers increases with ion fluence reaching the value of around 1.5 at.% for the highest ion dose, at a depth of 73 nm. XRD patterns show that the irradiation results in the decrease of the lattice constant in the range of 0.4160-0.4124 nm. Irradiation also results in the splitting of 200 line indicating the tetragonal distortion of CrN lattice. TEM studies demonstrate that after irradiation the columnar microstructure is partially destroyed within _90 nm, introducing a large amount of damage in the CrN layers. Spectroscopic ellipsometry analysis shows that the optical band gap of CrN progressively reduces from 3.47 eV to 2.51 eV with the rise in ion fluence up to 20?1015 ions/cm2. Four point probe measurements of the films indicated that as the Xe ion fluence increases, the electrical resistivity rises from 770 to 1607 ?Wcm. After post-implantation annealing crystalline grains become larger and lattice distortion disappears, which influences optical band gap values and electrical resistivity of CrN.

Improvement in Hardness of CrN Thin Film by Adding GaN and Evaluation of Its Solubility Limit

Improvement in Hardness of CrN Thin Film by Adding GaN and Evaluation of Its Solubility Limit

Sensitivity Improvement of MEMS Tactile Sensor with Cr-N Thin Film Strain Gauge

Sensitivity Improvement of MEMS Tactile Sensor with Cr-N Thin Film Strain Gauge

The role of the nitrogen flow rate on the transport properties of CrN thin films produced by DC magnetron sputtering

Thin films of CrN were synthesized in a DC magnetron sputtering system using a mixture of Ar+N2. The chemical composition and bonding configuration were examined using X-ray photoelectron spectroscopy (XPS) revealing CrN bonds. The stoichiometry variation dependence on the N2 flow was also analyzed using Auger spectroscopy. Both, The XPS and Auger analyses were performed in situ. A gradual increase was observed in the nitrogen concentration in the coatings as the N2 was increased into the reaction chamber. The electrical behavior was studied while varying the N2 concentration. A lower resistivity was observed as the nitrogen concentration was increased into the sample before reaching the stoichiometric concentration; however, the resistivity increased at higher nitrogen concentrations (overstoichiometric coatings). Considering that chromium is a magnetic material, a slope change in the resistivity was observed around the Néel temperature. Furthermore, the obtained Hall coefficient showed changes in the carrier type (negative or positive) depending on the nitrogen concentration of the CrN coatings.

Residual stress gradient of Cr and CrN thin films

In this work Cr, CrN thin films were grown by the Magnetron Sputtering technique on monocrystalline silicon (400) substrates. Also, a (Cr/CrN)2 multilayer film was grown in order to compare the values of stress between multilayer and single layers. The total thickness of all films was approximately equal to 1 μm. Structural characterization and residual stress measurements were performed by the grazing X-ray diffraction method and the data were collected at LNLS - Brazilian Synchrotron Light Laboratory. Different angles of incidence were selected in order to obtain values of residual stress at different penetration depths. A linear model of residual stress as a function of the depth profile from experimental data was obtained by using the Laplace transform. Results indicate smaller tensile residual stress at surface and higher stresses at film/substrate interface for the Cr monolayer and for the CrN phase in the (Cr/CrN)2 multilayer. On the contrary, the CrN film presented higher tensile stresses at surface.

Structural and magnetic phase transitions in chromium nitride thin films grown by rf nitrogen plasma molecular beam epitaxy

A magneto-structural phase transition is investigated in single crystal CrN thin films grown by rf plasma molecular beam epitaxy on MgO(001) substrates. While still within the vacuum environment following MBE growth, $\it in-situ$ low-temperature scanning tunneling microscopy, and $\it in-situ$ variable low-temperature reflection high energy electron diffraction are applied, revealing an atomically smooth and metallic CrN(001) surface, and an $\it in-plane$ structural transition from 1$\times$1 (primitive CrN unit cell) to $\mathrm{\sqrt{2}\times\sqrt{2}-R45^\circ}$ with a transition temperature of $\sim$ 278 K, respectively. $\it Ex-situ$ temperature dependent measurements are also performed, including x-ray diffraction and neutron diffraction, looking at the structural peaks and likewise revealing a first-order structural transition along both [001] and [111] $\it out-of-plane$ directions, with transition temperatures of 256 K and 268 K, respectively. Turning to the magnetic peaks, neutron diffraction confirms a clear magnetic transition from paramagnetic at room temperature to antiferromagnetic at low temperatures with a sharp, first-order phase transition and a N$\'{e}$el temperature of 270 K or 280 K for two different films. In addition to the experimental measurements of structural and magnetic ordering, we also discuss results from first-principles theoretical calculations which explore various possible magneto-structural models.