Properties Of ZrO2 Thin Films Research Articles

Exploring the impact of thin film thicknesses on the linear and nonlinear optical properties of ZrO2 thin film

Exploring the impact of thin film thicknesses on the linear and nonlinear optical properties of ZrO2 thin film

Comparative analysis of structural characteristics and thermal insulation properties of ZrO2 thin films deposited via chemical and physical vapor phase processes

ZrO2 is a flagship material for the development of efficient thermal barrier coatings not only for aerospace applications but also on steel molds for plastic injection, especially to produce high quality miniaturized parts of low environmental impacts. In the present study, ZrO2 thin films of thicknesses ranging between 4 and 40 μm were deposited on steel substrates by two key gas phase technologies, magnetron sputtering (PVD) and direct liquid injection metal organic CVD (DLI-MOCVD). The film morphology, structure and chemical composition were comparatively investigated and correlated to their heat transfer properties. All films were nearly stoichiometric and presented a columnar structure mainly formed of the monoclinic crystalline phase. The magnetron sputtering coatings were denser and smoother than the CVD ones, for which highly porous tree-like microstructures were observed without degradation of their mechanical properties. All films exhibited efficient thermal insulation properties, the thickest 40 µm magnetron sputtering coating displaying the most significant reduction in heat transfer. The CVD films provided the highest thermal gradient decrease across their thickness, probably thanks to their higher porosity associated to a multi-angle tree-like columnar structure, both acting as scattering zones of phonons involved in heat flow diffusion. By controlling the local deposition conditions influencing the nucleation and growth mechanisms, the film porous microstructure can thus be tuned to optimize the coating thermal properties.

Enhanced polarization and endurance properties of ZrO2-based ferroelectric capacitor using HfO2 interfacial layer

Recently discovered ferroelectricity in fluorite-structure ZrO2 thin film has attracted increasing and intense interest due to its lower crystallization temperature and higher content in nature in comparison to hafnium oxide. Here, the effect of HfO2 interfacial layer on the ferroelectric properties of ZrO2 thin films is investigated systematically by designing four types of interfacial structures. It is revealed that the ferroelectric orthorhombic phase, remanent polarization, and endurance can be improved in ZrO2 thin film by inserting both a top- and bottom-HfO2 interfacial layer. A maximal ferroelectric remanent polarization (2P r) of 53.4 μC cm−2 and an optimal endurance performance of 3 × 107 field cycles under frequency of 100 kHz are achieved in Pt/HfO2/ZrO2/HfO2/Pt capacitors, with ferroelectric stacks being crystallized at 450 °C via post-deposition annealing method. X-ray photoelectron spectroscopy analysis confirms that the HfO2 bottom-layer plays a very important role in the formation of a higher ratio o-phase, thus enhancing the ferroelectricity. These results suggest that designing appropriate interfaces would help achieve excellent ferroelectric properties in ZrO2 films.

Stabilization of the tetragonal phase in ZrO2 thin films according to ozone concentration using atomic layer deposition

In this study, we investigated the crystallographic and electrical properties of ZrO2 thin films prepared by an ozone-based atomic layer deposition process. Cyclopentadienyl tris(dimethylamino) zirconium [CpZr(NMe2)3] was used as the Zr precursor, and O3 was used as the reactant. ZrO2 films were produced using O3 in various concentrations from 100 to 400 g/m3. These thin films were used to fabricate metal–oxide–semiconductor capacitors, whose electrical properties were evaluated and correlated with crystallographic analysis. As the O3 concentration increased, the tetragonal phase of the ZrO2 film stabilized and the dielectric constant improved. However, the leakage current density characteristics concurrently deteriorated due to the high concentration of O3, increasing the number of grain boundaries in the ZrO2 film by increasing crystallinity. Thus, the concentration of O3 can control the number of OH groups of the ZrO2 film, affecting the device characteristics.

Optical and mechanical characterization of sol-gel thin films of ZrO2 stabilized with different Y2O3-doping mol%

The influence of the molar proportion of Y2O3 dopant (3, 9, and 12 mol%) on the optical and mechanical properties of ZrO2 thin films was studied. For this purpose, the three types of deposited thin films were first characterized microstructurally by spectrophotometry, optical microscopy, scanning electron microscopy, and X-ray diffractometry, and then their optical properties were measured by spectrophotometry and their mechanical properties by nanoindentation. It was found that they all crystallize in the cubic phase, even for dopant contents that would not do so in bulk materials. It was also found that, with increasing Y2O3 dopant, the refractive index increases while the optical absorption and extinction coefficients, the hardness, and the elastic modulus decrease. These trends are due to the poorer crystallinity and greater distortion of the crystal lattice of YSZ thin films with increasing Y2O3 dopant. The results are especially relevant for applications which require certain conditions of reflection and absorption of light energy, while maintaining optimal mechanical properties.

Effect of Annealing Temperature on the Structural and Optical Properties of ZrO2 Thin Films

Effect of Annealing Temperature on the Structural and Optical Properties of ZrO2 Thin Films

Impact of a TiN Capping Layer on Phase Transformation and Capacitance Enhancement in ZrO2

Tailoring of crystalline phases and dielectric properties of ZrO2 thin films are demonstrated by capping a nanoscale TiN layer prepared by plasma-enhanced atomic layer deposition. The in-plane tens...

The Influence of Annealing Temperature on the Structural and Optical Properties of ZrO2 Thin Films and How Affects the Hydrophilicity

Zirconium oxide (ZrO2) thin films were prepared by the sol-gel dip coating technique, in combination with annealing at different temperatures in air atmosphere, with the final goal of studying the water wettability of the surface. The annealing effects on the structural and optical properties of the ZrO2 films were investigated to check the characteristics of the material. X-ray diffraction (XRD) patterns of ZrO2 annealed at 450 °C and 550 °C show the formation of tetragonal phase, with layers constituted by nanoparticles with average particle size of 21 nm and 25 nm, respectively. Fourier-transform infrared spectroscopy (FT-IR) spectra revealed the presence of vibrational modes associated to ZrO2. Photoluminescence (PL) and ultraviolet-visible spectroscopy (UV–Vis) spectroscopy was used for optical properties. All deposited ZrO2 thin films presented a high optical transparency, with an average transmittance above 70% in the visible range (400–700 nm). The hydrophilic properties of ZrO2 films were characterized by means of the measurements of the contact angle. When the sample was annealed at 550 °C, the hydrophilicity reached the best behavior, which was explained as an effect of the structural and morphological change of the films.

Influence of substrate bias voltage on structure, mechanical and corrosion properties of ZrO2 thin films deposited by Reactive Magnetron Sputter Deposition

Zirconium oxide (ZrO2) thin films were grown onto 316L stainless steel by radio frequency magnetron sputtering (RFMS), at different substrate D.C. bias voltages (from 0 to −100 V). The deposition was performed using a pure zirconium target in the presence of an Ar-O2 gas mixture. The characterization of the deposited films was performed using scanning Electron Microscope, atomic Force Microscopy, X-rays diffraction, Raman spectroscopy, nanoindentation and potentiodynamic polarization. The structures of all ZrO2 films are crystalline. The monoclinic phase is predominant in the grounded films (0 V). However, the application of bias voltage depicts a tetragonal phase. Nanoindentation results reveal promoted values of the hardness of the ZrO2 films. Corrosion behavior of the films was studied in Hank's solution using the potentiodynamic polarization method. The comparison between the uncoated samples and the coated ones showed a reduction in corrosion current density for coated samples. The minimum corrosion rate of the film deposited at −100 V was 0.04992 mpy, which is about 18 times less than that of the uncoated steel (0.88135 mpy). The optimum anti-corrosion performance and hardness were obtained for ZrO2 deposited at a bias voltage of −100 V.

Structural, Optical, Electrical and Gas Sensor Properties of ZrO2 Thin Films prepared by Sol-Gel Technique

Structural, Optical, Electrical and Gas Sensor Properties of ZrO2 Thin Films prepared by Sol-Gel Technique

Zirconium Oxide Thin Films Obtained by Atomic Layer Deposition Technology Abolish the Anti-Osteogenic Effect Resulting from miR-21 Inhibition in the Pre-Osteoblastic MC3T3 Cell Line.

IntroductionThe development of the field of biomaterials engineering is rapid. Various bioactive coatings are created to improve the biocompatibility of substrates used for bone regeneration, which includes formulation of thin zirconia coatings with pro-osteogenic properties. The aim of this study was to assess the biological properties of ZrO2 thin films grown by Atomic Layer Deposition (ALD) technology (ZrO2ALD).MethodologyThe cytocompatibility of the obtained layers was analysed using the mice pre-osteoblastic cell line (MC3T3) characterized by decreased expression of microRNA 21-5p (miR-21-5p) in order to evaluate the potential pro-osteogenic properties of the coatings. The in vitro experiments were designed to determine the effect of ZrO2ALD coatings on cell morphology (confocal microscope), proliferative activity (cell cycle analysis) and metabolism, reflected by mitochondrial membrane potential (cytometric-based measurement). Additionally, the influence of layers on the expression of genes associated with cell survival and osteogenesis was studied using RT-qPCR. The following genes were investigated: B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), p53 and p21, as well as osteogenic markers, i.e. collagen type 1 (Coll-1), osteopontin (Opn), osteocalcin (Ocl) and runt-related transcription factor 2 (Runx-2). The levels of microRNA (miRNA/miR) involved in the regulation of osteogenic genes were determined, including miR-7, miR-21, miR-124 and miR-223.ResultsThe analysis revealed that the obtained coatings are cytocompatible and may increase the metabolism of pre-osteoblast, which was correlated with increased mitochondrial membrane potential and extensive development of the mitochondrial network. The obtained coatings affected the viability and proliferative status of cells, reducing the population of actively dividing cells. However, in cultures propagated on ZrO2ALD coatings, the up-regulation of genes essential for bone metabolism was noted.DiscussionThe data obtained indicate that ZrO2 coatings created using the ALD method may have pro-osteogenic properties and may improve the metabolism of bone precursor cells. Given the above, further development of ZrO2ALD layers is essential in terms of their potential clinical application in bone regenerative medicine.

The variations of hydrophilic self-cleaning properties and refractive index dependence in the ZrO2 thin films by Gamma Irradiation

ZrO2 thin film samples were produced by the sol-gel dip coating method. Four different absorbed dose levels (such as ~ 0.4, 0.7, 1.2 and 2.7 Gray-Gy) were applied to ZrO2 thin films. Hence, the absorbed dose of ZrO2 thin film was examined as physical dose quantity representing the mean energy imparted to the thin film per unit mass by gamma radiation. Modification of the grain size was performed sensitively by the application of the absorbed dose to the ZrO2 thin film. Therefore the grain size reached from ~50 nm to 87 nm at the irradiated ZrO2 thin film. The relationship of the grain size, the contact angle, and the refractive index of the irradiated ZrO2 thin film was investigated as being an important technical concern. The irradiation process was performed in a hot cell by using a certified solid gamma ray source with 0.018021 Ci as an alternative technique to minimize the utilization of extra toxicological chemical solution. Antireflection and hydrophilic properties of the irradiated ZrO2 thin film were slightly improved by the modification of the grain size. The details on the optical and structural properties of the ZrO2 thin film were examined to obtain the optimum high refractive index, self-cleaning and anti-reflective properties.

Dense electronic excitation induced modifications in nanocrystalline zirconium oxide thin films: Detailed analysis of optical and surface topographical

Ion irradiation is known to create structural disorder and crystallization improvement in the material. In the present study, focus is on the effect of high energy ion beam irradiation on the optical, surface morphological and structural properties of ZrO2 thin films of 200 nm grown on Si and glass substrate by RF sputtering technique. The prepared thin films were annealed at 600 °C and irradiated with swift heavy ions (SHI) of 120 MeV Ti9+ ion beam with varied fluences ranging from 5E11 to 2E13 ions/cm2. SRIM simulation reveals that the electronic energy losses (Se) dominate over the nuclear energy losses (Sn) and the projected range of the Ti ions was found to be 13.64 μm. Optical properties were studied by using UV-Vis and Photoluminescence (PL) spectroscopy. The transmittance of the ZrO2 samples lies in the range of (46–79%) and the Tauc's plot was used to calculate the optical band gap. PL spectroscopy demonstrates the emission spectrum using the excitation wavelength of 310 nm. The influence of SHI irradiation on the surface morphology of ZrO2 thin films was examined by Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The sectional analysis of AFM images reveals that the grain size decreases with increasing the ion fluences and lies in the range of 51-29 nm. The structural analysis of pristine and irradiated samples was done by using X-ray diffraction (XRD) technique. The crystallite size increases for the lower fluence up to 1E12 ions/cm2 and decreases at higher fluence due to the development of fragmentation by the effect of SHI irradiation. XRD patterns were used to calculate strain, stress, dislocation density and texture coefficient of the ZrO2 samples. Rutherford Backscattering Spectrometry (RBS) ensures the presence of Zr and O elements with the atomic fraction of 1: 2 and thickness (200 nm) of the samples was confirmed by simulating the RBS spectrum. The modifications induced in the properties of the ZrO2 thin films were mainly due to the electronic energy losses through the inelastic collision in the target material.

The variations of hydrophilic self-cleaning properties and refractive index dependence in the ZrO2 thin films by gamma irradiation

ZrO2 thin film samples were produced by the sol-gel dip coating method. Four different absorbed dose levels (such as ~ 0.4, 0.7, 1.2 and 2.7 Gray-Gy) were applied to ZrO2 thin films. Hence the absorbed dose of ZrO2 thin film was examined as physical dose quantity representing the mean energy imparted to the thin film per unit mass by gamma radiation. Modification of the grain size was performed sensitively by the application of the absorbed dose to the ZrO2 thin film.Therefore the grain size reached from ~50 nm to 87 nm at the irradiated ZrO2 thin film. The relationship of the grain size, the contact angle, and the refractive index of the irradiated ZrO2 thin film was investigated as being an important technical concern. The irradiation process was performed in a hot cell by using a certified solid gamma ray source with 0.018021 Ci as an alternative technique to minimize the utilization of extra toxicological chemical solution.Antireflection and hydrophilic properties of the irradiated ZrO2 thin film were slightly improved by the modification of the grain size. The details on the optical and structural properties of the ZrO2 thin film were examined to obtain theoptimum high refractive index, self-cleaning and antireflectiveproperties.

Investigation of the effect of anodization time and annealing temperature on the physical properties of ZrO2 thin film on a Si substrate

This research work studied the effects of various anodization times (5, 10, 15, 20 and 25 min) and various annealing temperatures (500, 600, 700, 800 and 900 °C) on ZrO2 thin film on a Si substrate. The ZrO2 thin film was prepared via sputtering and anodization processes on a Si substrate. The existence of Si, SiO2, m-ZrO2, t-ZrO2 and ZrSiO4 was confirmed by x-ray diffraction, Fourier transform infrared microscopy and Raman spectroscopy. In addition, NaOH was observed as a residue on the surface of the thin film. The grain size and microstrain of both m-ZrO2, and t-ZrO2 were calculated using the Williamson–Hall and/or Scherrer equation. The morphology of samples was examined by scanning electron microscopy. In contrast to unannealed samples, the annealed samples have a smaller grain size, less NaOH, and SiO2 with a smoother surface. However, the SiO2 existed when being annealed at higher temperatures (⩾800 °C).

Surface properties of ZrO2 thin film under Cl2/Ar plasma using angle-resolved X-ray photoelectron spectroscopy

ZrO2 thin films were investigated by surface characterization in a Cl2/Ar gas mixture adaptively coupled plasma system. The plasmas were characterized by optical emission spectroscopy analysis. The crystal structures of the films etched with gases at various mixing ratios were observed by X-ray diffraction. The results can show the damage caused by ion bombardment and chemical reaction of plasma on the crystalline structure of the ZrO2 surface. The chemical reactions of the etched ZrO2 films were investigated by angle-resolved X-ray photoelectron spectroscopy. The etching mechanism of ZrO2 thin films could be explained as Zr interacting with the Cl radical upon adding Cl2, but remaining at the surface owing to the low volatility of ZrClx. From the experimental results, the etching mechanism of ZrO2 was described as ion-assisted chemical reaction.

Effect of Mn doping on the structural and optical properties of ZrO2 thin films prepared by sol–gel method

Homogeneous and transparent Mn doped ZrO2 thin films were prepared by sol–gel dip coating method. The films were annealed in air atmosphere at 500°C. The X-ray diffraction pattern of the undoped ZrO2 thin film revealed a mixed phase of tetragonal and monoclinic ZrO2 with preferred orientations along T(111) and M(−111). Grazing Incidence X-ray Diffraction of Mn doped ZrO2 thin films reveals the introduction of Mn interstitial in ZrO2 which stabilize the mixed phase of ZrO2 into tetragonal phase. Atomic force microscope image shows the addition of catalyst (Mn) which stops isotropic agglomeration of particles, instead of anisotropic agglomeration that occurred resulting in growth of particles in certain direction. Average transmittances of >70% (in UV–vis region) were observed for all samples. The optical band gap decreased from 5.72 to 4.52eV with increase in Mn doping concentration. The reduced band gap is due to the introduction of impurity levels in the band gap, by incorporation of the metal ions into the ZrO2 lattice. The d-electron of Mn (t2g level) can easily overlap with the ZrO2's valence band (VB) because t2g of Mn is very close to VB of ZrO2. This overlap caused a wide VB and consequently decreases the band gap of ZrO2. The photoluminescence (PL) spectrum of undoped zirconia thin film exhibits an intense near band edge emission peak at 392.5nm (3.15eV) and weak emission peaks at 304 (4.07eV), 604nm (2.05eV) and 766nm (1.61eV). Additional PL peaks were observed for Mn doped ZrO2 located at around 420, 447 (blue), 483 (blue) and 529 (green)nm respectively. These peaks were due to the redox properties of various valence state of Mn in ZrO2. The prepared Mn doped ZrO2 thin films can be applied in optical devices.

Effect of process temperature on the structural and electrical properties of atomic layer deposited ZrO2 films using tris(dimethylamino) cyclopentadienyl zirconium precursor

The authors investigate the deposition of ZrO2 by atomic layer deposition (ALD) process using tris(dimethylamino) cyclopentadienyl zirconium (Cp-Zr) as a precursor, and the effect of deposition temperature on the structural and electrical properties of ZrO2 thin films are studied. The ALD process window of Cp-Zr is found at 300–350 °C, and no noticeable change in the film composition occurs within the ALD process window and the films are all stoichiometric. However, the crystallinity of the film is significantly affected by the deposition temperature. At 300 °C, only the cubic and tetragonal phases are detected, while the monoclinic peak starts to appear at 325 °C. Consequently, the highest dielectric constant (35.8) is observed for the ZrO2 films deposited at 300 °C. In contrast, ZrO2 films deposited at 350 °C show the lowest leakage current. This trend is due to the lower carbon impurity contents along with the increase in deposition temperature. To study the electrical properties of ZrO2 films in more detail, capacitance–voltage hysteresis measurements are carried out; the hysteresis is reduced abruptly with an increase in deposition temperature.

TEMAZ/O3 atomic layer deposition process with doubled growth rate and optimized interface properties in metal–insulator–metal capacitors

ZrO2 is of very high interest for various applications in semiconductor industry especially as high-k dielectric in metal–insulator–metal (MIM) capacitor devices. Further improvement of deposition processes, of material properties, and of integration schemes is essential in order to meet the strict requirements of future devices. In this paper, the authors describe a solution to solve one of the key challenges by reducing the process time of the bottle neck high-k atomic layer deposition (ALD). The authors extensively optimized the most common ALD process used for the ZrO2 deposition (TEMAZ/O3) resulting now in a doubled growth rate compared to the published growth rates of maximum 1 Å/cycle. Chemical reactions explaining the origin of the high growth rate are proposed by theoretical process modelling. At the same time, the outstanding electrical properties of ZrO2 thin films could be preserved. Finally, the integration of the ZrO2 process in MIM capacitor devices with TiN electrodes was evaluated. Thereby, the known effect of TiN bottom electrode oxidation by the O3 process was analyzed and significantly reduced by different integration approaches including wet chemical treatments and ALD process variations. The resulting MIM capacitors show low leakage current and high polarity symmetry.

Thermal treatment effect on the optical properties of ZrO2 thin films deposited by thermionic vacuum arc

This paper shows the ex situ thermal treatment effects of the ZrO2 thin films obtained by TVA (thermionic vacuum arc) technique on the optical properties (e.g., transmittance, refractive index and band-gap energy) of ZrO2 thin films. The crystal structure, surface and optical properties were investigated for ZrO2 thin films deposited on glass substrates by thermionic vacuum arc (TVA) method. The thermal treatment effect on the optical properties of the thin films was determined. The XRD analysis showed that the deposited ZrO2 thin films have baddeleyite (monoclinic) and zirconium (hexagonal) structures. The thicknesses and refractive index were determined by interferometric measurements. The thin films were thermal treated at different temperatures (350 °C, 450 °C and 550 °C), and the analysis showed that the optical properties of ZrO2 deposited thin films were improved by thermal treatment at 450 °C.