Dc Substrate Bias Research Articles

Planar deposition of Nb thin films by HiPIMS for superconducting radiofrequency applications

Cost efficiency and sustainability are critical challenges for future accelerator machines. Nb-coated Cu (Nb/Cu) superconducting radiofrequency (SRF) accelerating cavities, while requiring R&D to meet high acceleration gradient performance standards, show potential for addressing these challenges. Defects in the Nb layer responsible for the deterioration of cavity performance have been linked to the underlying Cu substrate. This study investigates a novel optimization method by mitigating the substrate surface’s impact on deposited Nb, using High Power Impulse Magnetron Sputtering alongside a DC substrate bias (from −50 to −300 V). Trenched silicon substrates are chosen to emulate substrates with exceptionally rugged surface characteristics. Film deposition is investigated both experimentally and through kinetic Monte Carlo simulations. Higher DC voltages are shown to eliminate self-shadowing during the coating process via improved incident ionic flux directionality, enhanced adatom mobility and increased re-sputtering rates, ultimately yielding flat and densely-packed films. The influence of the substrate’s shape on the film’s surface was found to decrease exponentially with increasing ion bombardment energies. Films sputtered under high DC bias conditions (−300 V) exhibited complete planarization with a 30% re-sputtering rate. Strategies for applying this technique to Nb/Cu SRF cavities, enhancing their viability for future particle accelerators, are also discussed.

Polypyrrole film formation using DC biasing of substrate in in-solution plasma process

Beyond the existing in-solution plasma (iSP) process used for nanoparticle synthesis, polymer film synthesis has recently been demonstrated via iSP, which occurs at a specific cycle in a substrate with electrical potential. Herein, we propose an iSP reactor designed to tune the characteristics of polypyrrole (PPy) films by applying varied DC biases to the substrate during the solution plasma process. Applying DC bias to the substrate notably enhances the iSP during the negative cycle, thereby generating ionic precursors from pyrrole monomers for PPy film formation. These films demonstrated morphological variances as a function of the applied VDC. At a low voltage (VDC = 0.5 kV), a uniform film was formed via a layer-by-layer growth mechanism, and as the voltage was increased, the film exhibited a structured morphology. Specifically, at VDC = 0.5 kV, the PPy film was successfully coated onto a finely patterned electrode. The proposed iSP process, under specific DC biasing conditions, enables polymer coating without necessitating additional chemicals, catalysts, or masks. This method holds potential for a wide range of applications.

Investigating the Metal-Plasma Interaction during the Patterning of MgZnO Alloys, Used for Compute and Memory Applications

Magnesium Zinc Oxide (MgZnO) is a novel metal alloy being considered for advanced memory applications. When used as a dielectricum in transistors in dynamic random-access memory (DRAM) [1,2] or core elements in resistive random-access memory (RRAM) [3,4], MgZnO exhibits the potential to display low cutoff current [Ioff], high mobility [3], and low processing temperature [1]. Therefore, minimal damage-inducing patterning of the alloy for use in electrical nanoscale devices is needed.During the etching process, MgZnO film may be chemically and physically damaged, impacting its electrical performance. Changes in chemical composition and diffusion of etchants into the material are some types of chemical damages observed during etching. These can impact carrier mobility within the material. Physical damage consists of modified roughness, profile distortion, and redeposition on the pattern sidewalls. These are all critical issues because carrier transport in transistor channels is significantly affected by interface roughness between the channel and gate insulator [5]. The etch process developed should preserve the chemical composition and roughness in MgZnO and provide good selectivity when patterning other layers of the stack and hard mask (HM). There are three methods for dry etching consisting of physical, chemical, and physical-chemical mechanisms [6]. Pure physical etching is not selective and pure chemical etching can be isotropic. Reactive ion etching (RIE) is used in this study to generate an etching mechanism that can provide an optimal combination of chemical and physical etching [6].In this work, we carried out the etch investigation of MgZnO film using an RIE-transformer coupled plasma (TCP) system. 10 nm MgZnO films are deposited on a 50 nm SiO2 layer/Si substrate. The impact of different gas mixing ratios, RF power, DC substrate bias, and process pressure are studied. The etching of MgZnO thin films is carried out using Cl2/CH4/Ar mixture. Cl2 increases chemical reactivity by creating MgCl2 [7] and ZnCl2 [8] by-products that are easier to remove than breaking Mg-O and Zn-O bonds from the films. Moreover, the addition of CH4 produces organometallic volatile etch by-product – Zn (CH3)2 (boiling point: 46°C) [8]. Therefore, MgZnO is to be etched partly by physical and chemical mechanisms. These hypotheses are studied in detail by carrying out in-depth X-ray photoelectron spectroscopy (XPS) based composition analysis on individual ZnO and MgO surfaces subjected to the aforementioned chemistry (Fig.1(a, b)). In addition, by increasing the voltage and power, the etching performance of MgZnO is further improved due to increasing ion energy and the presence of more active species in the plasma via higher dissociation and ionization, respectively (Fig.1(c, d)). These investigations should enable a more systematic patterning study of MgZnO-based features at different scaled dimensions and densities.

Nitrogen-containing diamond-like carbon deposited on glass substrate via filtered cathodic vacuum arc with high-frequency pulsed DC substrate bias

This research investigates the properties of nitrogen-containing diamond-like carbon (N-DLC) coatings deposited on glass substrate using a high-frequency pulsed-DC substrate bias. The study involved comprehensive investigations to understand how variations in carbon bonding affect the properties of N-DLC coatings. By adjusting the voltage, frequency and duty ratio of the pulsed bias, it was possible to deposit an optical coating with a transmittance of up to 52 % at range of 800–2500 nm while effectively preventing the peeling of the DLC coating on the glass. With increasing the clustered graphite structure in the DLC coating, the sheet resistance was lowered from 2370 kΩ/□ to 36 kΩ/□, and the electrical properties were also improved. The findings provide valuable insights for optimizing N-DLC coatings for non-conductors, e.g., glass, rubber, polymer, and engineering ceramic.

Evolution of microstructure and properties of TiNbCrAlHfN films grown by unipolar and bipolar high-power impulse magnetron co-sputtering: The role of growth temperature and ion bombardment

Growth temperature (Ts) and ion irradiation energy (Ei) are important factors that influence film growth as well as their properties. In this study, we investigate the evolution of crystal structure and residual stress of TiNbCrAlHfN films under various Ts and Ei conditions, where the latter is mainly controlled by tuning the flux of sputtered Hf ions using bipolar high-power impulse magnetron (BP-HiPIMS). The results show that TiNbCrAlHfN films exhibit the typical FCC NaCl-type structure. By increasing Ts from room temperature to 600 °C, the film texture changes from high-surface-energy (111) to low-surface-energy (100) accompanied by a higher crystallinity in the out-of-plane direction and a more disordered growth tilt angle to the surface plane. In addition, compressive stress decreases with increasing Ts, which is ascribed to changes in the film growth both in the early and post-coalescence stages and more tensile thermal stress at elevated Ts. In contrast, a clear texture transition window is seen under various Ei of Hf+ ions, i.e., high-surface-energy planes change to low-surface-energy planes as Ei exceeds ∼110 eV, while low-surface-energy planes gradually transform back to high-surface-energy planes when Ei increases from 210 to 260 eV, indicating renucleation events for Ei > 210 eV. Compressive stress increases with increasing Ei but is still lower than that of a reference series with DC substrate bias UDC = −100 V. The study shows that it is possible to tailor properties of FCC-structured high-entropy nitrides by varying Ts and Ei in a similar fashion to conventional transition metal nitrides using the approach of unipolar and bipolar HiPIMS co-sputtering.

Dense and hard TiWC protective coatings grown with tungsten ion irradiation using WC-HiPIMS/TiC-DCMS co-sputtering technique without external heating

Titanium tungsten carbide (TiWC) coatings are deposited by a combined high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) technique. No external heating is applied during deposition phase, instead, the thermally driven adatom mobility is substituted by heavy ion irradiation. DCMS sources equipped with titanium carbide targets provide constant neutral fluxes to establish the predominant coating structures, whereas tungsten carbide target in HiPIMS mode serves as the source of heavy metal-ions. Substrate bias of −60 V is synchronized to W+ ion-rich time domains of HiPIMS pulses to minimize the contribution from working gas ions. The influence of W+ ion flux intensity, controlled by varying peak target current density (JT), on film properties is investigated. X-ray photoelectron spectroscopy reveals the presence of over stoichiometric carbon forming an amorphous phase, the amount of which can be fine-tuned by varying JT. Changes in film composition as a function of JT are explained based on the in-situ ion mass spectroscopy analyses. Dense TiWC coatings by hybrid process exhibit hardness higher than 30 GPa, which are comparable to TiWC films deposited by DCMS with dc substrate bias and external heating. The relative energy consumption in the hybrid process is reduced by 77 % as compared to high-temperature DCMS processing.

Thickness-Dependent Nonlinear Electrical Conductivity of Few-Layer Muscovite Mica

We report on the direct current (dc) current-voltage ($I$-$V$) characteristics of few-layer muscovite mica (MuM) flakes exfoliated and transferred onto $\mathrm{Si}\mathrm{O}$${}_{2}$/$\mathrm{Si}$ substrate, under different substrate dc bias voltages. Contrary to usual observations in conventional two-dimensional systems, we observe an increase in the in-plane electrical conductivity with a reducing thickness of MuM flakes. At a given voltage, the electrical conductivity of approximately five-layered MuM flake (${T}_{3}$) is 3 orders of magnitude larger than that in approximately ten-layered MuM flake (${T}_{2}$). The $I$-$V$ characteristics are used to analyze the mechanism of conduction. The model-based analysis reveals the hopping-conduction mechanism to be dominant as compared to the Poole-Frenkel effect. The thickness-dependent work function is measured using Kelvin probe force microscopy for a MuM flake on $\mathrm{Si}$ substrate. Assuming that the measured work function is correlated with the Fermi level, we report an upward movement of the Fermi level, toward the conduction band with the reducing thickness of MuM flakes, indicating an increase in the conduction-band carrier density. The observed increase in conductivity in ${T}_{3}$ when compared to ${T}_{2}$ may be attributed to surface doping due to the increased contribution from ${\mathrm{K}}^{+}$ ions and lattice relaxation. Our results show that there is a possibility of using few-layer mica as a wide-band-gap semiconductor and that it can open up different avenues for two-dimensional electronic devices.

Growth of diamond-like carbon films with significant nanocrystalline phases in a low-pressure high-density CH4 plasma in ICP-CVD: Effect of negative dc substrate bias

Working at relatively low-temperature and low-pressure, the development and optimization of diamond-like carbon (DLC) films with significant nanodiamond components on inexpensive glass substrates, without conventional pre-treatment by diamond powders, is the main objective of the present work. Using the most familiar CH4-precursors diluted by Ar in a high-density plasma triggered at high rf power (900 W) in a planar inductively-coupled plasma chemical vapour deposition (ICP-CVD) system, DLC thin-films are prepared via optimization in the flow rate of the precursor gas at 30 mTorr (∼4 Pa) pressure and 450 °C substrate temperature and, further by applying negative dc-bias to the substrates. The optimized samples obtained with negative substrate-bias possess good crystalline properties. From Raman results, the most crystalline sample is obtained with characteristic minimum ID/IG ratio reduced from 0.75 to 0.61, maximum IDia/ID enhanced from 0.94 to 1.09, and the sp3 hybridized CC bonds increased from 44% to ∼64% at a substrate-bias of –40 V. The residual stress, and the optical band gap were calculated from Raman analysis. The optimized DLC film exhibits a high optical band gap (3.71 eV) as calculated from Tauc’s plot analysis of the UV–Vis data. The well-identified 〈111〉 crystallographic planes in the TEM micrograph demonstrate a significant fraction of nanocrystalline diamond component in the optimum DLC film.

Preparation of boron doped diamond-like carbon films in a low-pressure high-density plasma in RF ICP-CVD

The main objective of this work is to prepare electrically conducting boron doped diamond-like carbon (DLC) films with good crystalline qualities and high optical band gap in a low pressure and high-density plasma in an RF ICP CVD system. The main precursor gas used was CH4, with Ar being the diluent gas. B2H6 in He was used as the main source of boron, as the dopant, in the system. Planar inductively coupled technique enables the plasma to be ignited at a very low deposition pressure of 30 mTorr. A substrate temperature of 450 °C, a 900 W of RF power and a dc substrate bias of −40 V were used during the sample growth. By varying the B2H6/CH4 (=R) ratio, the optimized condition for preparing boron doped DLC thin films was obtained at R = 1. Raman analysis showed that this sample has the minimum ID/IG ratio ∼0.83, a maximum IDia/ID (∼1.18) and a maximum IDia/IG (∼0.98). The sp3 C-C content of 48.05% was calculated from XPS. A high optical band gap of ∼3.8 eV was obtained from the UV–Vis spectra. Boron doping was confirmed from the Raman, XPS and electrical conductivity measurements.

Autogenic single p/n-junction solar cells from black-Si nano-grass structures of p-to-n type self-converted electronic configuration.

Photovoltaic performance of solar cells automatically improves when the absorber layer itself simultaneously acts as the anti-reflection nanostructure with an enhanced active absorber area on the front surface. Combined physical and chemical etching of p-c-Si wafers by (Ar + H2) plasma in inductively coupled low-pressure plasma CVD produces various nanostructures with subsequent minimization of reflectance. At a reduced temperature, the rate constant of thermal diffusion of atomic-H in the Si-network becomes smaller, leading to enhanced chemical etching reactions that further increase at an elevated RF power. Regrowth of the SiHn precursors produced by etching and subsequent hydrogenation in the plasma develops a high density of elongated nano-grass structures, which further align with sharp tips via Ar+ ion bombardment and elimination of loosely bound amorphous over-layers, on application of negative dc substrate bias during real-time etching and regrowth. A significantly reduced reflectance (∼0.5%) via coherent light trapping within the uniformly distributed vertically aligned nano-grass surfaces evolves truly black-silicon (b-Si) nanostructures, which further self-convert from the p-type to n-type electronic configuration via etching-mediated modification of B-H bonds from BH1 to BH2 and/or BH3 states, producing autogenic p/n junctions. Using (Ar + H2) plasma etched b-Si nano-grass structures at low temperature (∼200 °C), one-step fabrication of autogenic single p/n-junction proof-of-concept solar cells is accomplished. There is plenty of room for further progress in device performance.

DC substrate bias enables preparation of superior-performance TiN electrode films over a wide process window

When stacking with various underlying layers in the microelectronics devices, titanium nitride electrode films are not only desired to meet the critical requirements for high conductivity and low surface roughness, but also to be deposited over a wide processing window. In this work, a negative substrate bias was introduced as an additional power for the reactive sputtering of titanium nitride films. Upon systematically adjusting the substrate bias, working pressure and substrate temperature, the evolution of film properties was studied in detail in terms of resistivity, growth rate, crystal structure, surface morphology and composition. It was shown that an optimized substrate bias is beneficial for film densification and grain reorientation. As a result, titanium nitride films with superior-performance (resistivity ≤ 53.2 μΩ·cm and surface roughness ≤0.66 nm) can be grown over a wide working pressure range of 0.3–1.1 Pa and substrate temperature range from room temperature to 350 °C.

VO2 thin films with low phase transition temperature grown on ZnO/glass by applying substrate DC bias at low temperature of 250 °C

High-performance vanadium dioxide films with low phase transition temperatures of 40–50 °C were successfully fabricated by applying various negative substrate bias voltages at a low substrate temperature of 250 °C. This low-temperature preparation method and the films’ thermochromic properties may provide useful suggestions for industrial production of VO2 films for smart window applications. The effects of the negative substrate dc bias voltage on the microstructure, surface morphology, and optical and electrical performance of the VO2 films were characterized. X-ray diffraction showed that the residual compressive stress in the films increased as the substrate bias increased, and the maximum value can reach −576 MPa. Temperature-dependent sheet resistance measurement showed that the transition temperature (τc) and room-temperature sheet resistance decreased significantly with increasing substrate bias, and the lowest value of τc is 38.5 °C. The calculated solar energy modulation ability (ΔTsol) of the VO2 film fabricated under a substrate bias voltage of −175 V at 250 °C is approximately 9.73%, which may indicate strong potential for application in smart energy-efficient windows produced industrially at a low substrate temperature.

Growth (AlCrNbSiTiV)N thin films on the interrupted turning and properties using DCMS and HIPIMS system

This paper determines the optimal settings in the deposition parameters for (AlCrNbSiTiV)N high-entropy alloy (HEAs) nitride films that are deposited on CBN cutting tools and glass substrates. We use direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS), with Ar plasma and N2 reactive gases. Experiments with the grey-Taguchi method are conducted to determine the effect of deposition parameters (deposition time, substrate DC bias, DC power and substratetemperature) on interrupted turning 50CrMo4 steel machining and the films’ structural properties. Experimental result shows that the multiple performance characteristics for these (AlCrNbSiTiV)N HEAs film coatings can be improved using the grey-Taguchi method. As can be seen, the coated film is homogeneous, very compact and exhibits perfect adherence to the substrate. The distribution of elements is homogeneous through the depth of the (AlCrNbSiTiV)N film, as measured by an auger electron nanoscope. After interrupted turning with an (AlCrNbSiTiV)N film coated tool, we obtain much longer tool life than when using uncoated tools. The correlation of these results with microstructure analysis and tool life indicates that HIPIMS discharge induced a higher (AlCrNbSiTiV)N film density, a smoother surface structure and a higher hardness surface.

Enhanced Crystallinity of h‐BN Films Induced by Substrate Bias During Magnetron Sputtering

The synthesis of uniform, highly crystalline thin films of hexagonal boron nitride (h‐BN) is an important step for its applications in multilayered devices with other emerging 2D materials. We report on the growth of high purity h‐BN by reactive magnetron sputtering from a pure B target in an Ar/N2 plasma. Enhanced h‐BN crystallinity on Ni substrates was achieved using a negative DC substrate bias during deposition, which served to increase the energy of incident ions, causing higher adatom mobility and re‐sputtering of weakly bound species on the growth surface. Growth rates between 0.002 to 1.1 Å s−1 were observed as the power was varied from 10 to 200 W and the growth temperature was either room temperature or 850 °C. BN films grown on a r‐sapphire substrate or a silicon (100) wafer with native oxide were smooth but amorphous under all conditions. Crystalline growth was observed on unbiased Ni foil substrates heated to 850 °C provided the growth rate was below 0.01 Å s−1, but the films were a non‐uniform mixture of h‐BN crystals and a disordered phase. Using a −50 V substrate bias, a high degree of h‐BN crystallinity and film homogeneity over large areas on the Ni substrate was achieved.

Improvement of crystallinity for poly-Si thin film by negative substrate bias at low temperature

Polycrystalline silicon (p-Si) thin films are fabricated by plasma enhanced chemical vapor deposition (PECVD) at low substrate temperature (180°C) with high-hydrogen dilution. Negative DC substrate bias is applied during the deposition process for improving the crystallinity of thin films. It is found that there is a phase transition from nanocrystalline phase to polycrystalline phase at negative bias=50V, as identified by scanning electron microscopy (SEM). The optimized p-Si thin film with large grains (~480nm) are obtained at negative bias=100V. The deconvoluted Raman spectra reveal that the p-Si thin film is a mixture including amorphous silicon (a-Si), nanocrystalline silicon (nc-Si) and p-Si, and the crystalline volume fraction gradually increases with the substrate negative bias in the range of 0–100V. The impacts of negative bias on the optical and electrical properties of p-Si thin films have been investigated. The growth mechanism of the p-Si grains has been discussed in detail. A grain-merging model is proposed for explaining the effect of negative bias on the formation of large p-Si grains at low temperature.

Extended x-ray absorption fine structure measurements on radio frequency magnetron sputtered HfO2 thin films deposited with different oxygen partial pressures.

Two sets of HfO2 thin film have been deposited by the radio frequency magnetron sputtering technique at various oxygen partial pressures, one set without any substrate bias and another set with a 50 W pulsed dc substrate bias. The films have been characterized by extended x-ray absorption fine structure (EXAFS) measurements at the Hf L3 edge, and the structural information obtained from analysis of the EXAFS data has been used to explain the macroscopic behavior of the refractive index obtained from spectroscopic ellipsometry measurements. It has been observed that the variation of refractive index with oxygen partial pressure depends on the Hf-Hf bond length for the set of films deposited without substrate bias, while for the other set of films deposited with pulsed dc substrate bias, it depends on the oxygen coordination of the nearest neighbor shell surrounding Hf sites.

Investigating the chemical mist deposition technique for poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) on textured crystalline-silicon for organic/crystalline-silicon heterojunction solar cells

Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated in terms of cavitation frequency f, solvent, flow rate of nitrogen, substrate temperature Ts, and substrate dc bias Vs as variables for efficient PEDOT:PSS/crystalline silicon (c-Si) heterojunction solar cells. The high-speed-camera and differential mobility analysis characterizations revealed that the average size and flux of PEDOT:PSS mist depend on f, type of solvent, and Vs. Film deposition occurred when positive Vs was applied to the c-Si substrate at Ts of 30–40 °C, whereas no deposition of films occurred with negative Vs, implying that the film is deposited mainly from negatively charged mist. The uniform deposition of PEDOT:PSS films occurred on textured c-Si(100) substrates by adjusting Ts and Vs. The adhesion of CMD PEDOT:PSS film to c-Si was greatly enhanced by applying substrate dc bias Vs compared with that of spin-coated film. The CMD PEDOT:PSS/c-Si heterojunction solar cell devices on textured c-Si(100) in 2 × 2 cm2 exhibited a power conversion efficiency η of 11.0% with better uniformity of the solar cell parameters. Furthermore, η was increased to 12.5% by adding an AR coating layer of molybdenum oxide MoOx formed by CMD. These findings suggest that CMD with negatively charged mist has great potential for the uniform deposition of organic and inorganic materials on textured c-Si substrates by suitably adjusting Ts and Vs.

Influence of pulsed bias duty cycle variations on structural and mechanical properties of arc evaporated (Al,Cr)2O3 coatings

(AlxCr1−x)2O3 coatings were synthesised by cathodic arc evaporation applying DC and pulsed substrate bias voltages to study the impact of different bias duty cycle settings on structure and morphology as well as mechanical and tribological properties. X-ray diffraction revealed a corundum-type (AlxCr1−x)2O3 phase structure for Al contents x≤0.5 and the formation of an additional face-centred cubic (Al–Cr–O) phase for x≥0.5 for the pulsed bias situation, independently of the chosen duty cycle. In general, changes of the duty cycle in the manner of decreasing the electron current time duration along with an extension of the ion bombardment during growth lead to a reduction of the coatings' domain size, the formation of compressive residual stress as well as increasing coating hardness and Young's modulus. An amorphous-like coating microstructure accompanied with diminished mechanical properties was observed when a DC substrate bias voltage was applied. The investigations illustrate the potential of tuning the properties of arc evaporated oxide coatings by adjusting the energetic particle bombardment during growth.

Superconducting TiN Films Sputtered Over a Large Range of Substrate DC Bias

We have investigated properties of superconducting titanium nitride (TiN) films that were sputtered over a large range of RF-induced DC bias voltage applied to the substrate. Films grown with the largest bias voltages contained cubic TiN phases with a large fraction of the (200) crystalline growth orientation. These films also contained the smallest concentrations of oxygen impurities, resulting in stoichiometric TiN. Over the range of bias, variations of the stress from slightly tensile to highly compressive were measured and correlated to crystallinity of the (200) growth. The films exhibited highly uniform thickness and resistivity, and show the potential for yielding reproducible low-temperature devices. Finally, coplanar resonators fabricated with the films exhibited high kinetic inductance and quality factor, where the latter was obtained in part from temperature-dependent frequency shifts.

Statistical optimization and fretting fatigue study of Zr/ZrO2 nanotubular array coating on Ti–6Al–4V

Herein, the fretting fatigue behavior of zirconium nanotube arrays on the surface of Ti–6Al–4V is studied. Initially, a thin film of pure zirconium (Zr) was deposited onto a Ti–6Al–4V substrate using physical vapor deposition (PVD) magnetron sputtering for the primary layer at varying DC power, temperature and substrate bias voltage values. To obtain higher adhesion strength, the Taguchi optimization method was used to estimate the optimum coating parameters, while a Pareto ANOVA was employed to determine the significant parameters. The strongest coating adhesion, as determined by a scratch force test, was achieved at 300W DC power, 200°C and a 75V bias voltage. Consequently, nanotubes were produced via Zr anodization in an NH4F electrolyte solution (95 glycerol:5 water) at different times and at a constant potential of 60V (second layer). The fretting fatigue behavior of anodized samples annealed at 400°C and 800°C was investigated. The results indicate that the fretting fatigue life of the ZrO2 nanotube-coated samples was significantly improved at low and high cyclic fatigue at an annealing temperature of 400°C compared to the uncoated samples.