ZrO2 Deposition Research Articles

Interfacial layer suppression in ZrO2/TiN stack structured capacitors via atomic layer deposition

Controlling the formation of interfacial layers in dynamic random-access memory (DRAM) capacitors is crucial because it affects electrical performance, such as increasing the equivalent oxide thickness. This study investigates the formation of an interfacial layer during atomic layer deposition (ALD) of ZrO2 on TiN electrodes and examines its influence on electrical properties. Utilizing O3 and H2O as oxygen sources, we quantitatively identified notable differences in the formation of the interfacial TiOx layer. Using O3 results in a thicker TiOx layer with fewer impurities, which lowers the leakage current, whereas H2O creates a thinner interfacial layer with higher impurity levels, leading to an increased leakage current. To optimize these effects, we developed a two-step ALD process that combines both oxygen sources, reducing the interfacial layer thickness while maintaining low leakage currents. This approach significantly improved the electrical performance of capacitors. Furthermore, similar results were observed for HfO2/TiN systems, suggesting that our findings are broadly applicable to high-k dielectric materials.

Nafion/ZrO2 Modified NiTi Orthodontic Wire: Preparation, Material Characterization, and Corrosion Studies

Background: Nickel-titanium (NiTi) orthodontic wires are widely used in dental corrective procedures due to their high mechanical properties and cost-effectiveness. However, they are prone to oral corrosion, leading to mechanical deterioration, aesthetic issues, and potential health concerns. Objective: This study aims to improve the corrosion resistance and durability of NiTi orthodontic wires by employing zirconium dioxide (ZrO2) and Nafion coating with the goal of enhancing wire performance. Methods: Two types of NiTi wires were evaluated: a standard, unmodified wire as a control and another wire treated with electrodeposited ZrO2 film and Nafion (Naf) coating. Surface analysis was conducted using various techniques, including Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDX) analysis. Results: The uncoated NiTi wire exhibited a corrosion rate of 4.436× 10-1 mm/year, whereas the Naf/ZrO2-coated NiTi wire showed a corrosion rate of 4.068× 10-1 mm/year, indicating that the Naf/ZrO2 coating acted as a protective layer. Additionally, the ZrO2 layer provided poor electrical conductivity, resulting in slightly higher impedance compared to bare NiTi. The coating served as a barrier, which significantly enhanced corrosion resistance and improved the wire lifespan. Conclusion: Electro-modification through ZrO2 deposition and Nafion coating significantly improved the corrosion resistance and overall durability of NiTi orthodontic wires, offering a promising advancement for their use in dental orthodontics. This study underscores the potential of ZrO2 and Nafion coating to enhance the corrosion resistance and longevity of NiTi orthodontic wires.

Joule heat induced ultrafine ZrO2/C composites for enhanced microwave absorption

Lightweight absorbers with effective broad absorption and high thermal stability are highly desirable in the field of electromagnetic wave absorption. In this work, we introduce a facile carbon thermal shock method to prepare ZrO2/C composites using UIO 66 (Zr) as the precursor. The instant heating and cooling process ensures the uniform deposition of nano-sized ZrO2 (ca. 5–15 nm) on graphene, exhibiting an ultrahigh interfacial number density of ca. 1015 m−2 that favors polarization loss. Due to the synergetic effect of dielectric loss and impedance matching, the prepared ZrO2/graphene composites show tunable wide-microwave absorption performance by adjusting the heat temperature, and possess a wide absorption band covering the entire X and Ku band. Notably, the ZrO2/graphene composites show high thermal stability up to 1000 °C, which presents great potential for microwave absorption applications.

Investigation of intermediates formation in the CO2 hydrogenation to methanol reaction over Ni5Ga3-ZrO2-SBA-15 materials prepared via ZrO2 atomic layer deposition

The production of methanol through CO2 hydrogenation holds great promise for efficient CO2 utilization. The development of catalysts that exclusively favor the formate route is desirable as this enhances methanol selectivity and avoids CO formation. Here, the synthesis of two groups of Ni5Ga3-ZrO2-SBA-15 based materials was studied through the atomic layer deposition (ALD) of ZrO2. The first group was prepared applying ZrO2 ALD over a Ni5Ga3/SBA-15 material and the second group was prepared doing ZrO2 ALD over a mesoporous silica, Santa Barbara Amorphous (SBA-15), followed by impregnation with Ni5Ga3. Some characterization techniques were employed to assess the effectiveness of the ZrO2 ALD on both groups. Interestingly, it was observed that ZrO2 deposition was less effective over the Ni5Ga3/SBA-15 sample compared to its deposition over pure SBA-15, and through XPS analysis was noticed that ZrO2 is probably covering part of the Ni5Ga3 alloys. Furthermore, in situ DRIFTS analysis was performed during reaction conditions and revealed that ZrO2 deposition facilitated the formation of formate and methoxy intermediates in both material groups. The increase in the ZrO2 ALD cycles increased the formate and methoxy bands and decreased CO-related bands. After 6 cycles, only the ZrSBANG_6 catalyst exclusively followed the formate route, as only formate and methoxy bands were present.

Crystallinity-Controlled Atomic Layer Deposition of Ti-Doped ZrO2 Thin Films

We investigated Ti-doped ZrO2 deposition using a cyclopentadienyl tris(dimethylamino) zirconium (CpZr(NMe2)3) precursor and a titanium tetraisopropoxide (TTIP) precursor using an O3 thermal atomic layer deposition process. In addition, the effect of Ti doping concentration on the chemical bonding and electrical properties of the Ti-doped ZrO2 thin films was studied. O3 was used at a high concentration of 400 g m−3. We varied the Ti doping concentration by controlling the rate of the supercycle process in the ZrO2 process window of 200 °C–300 °C. As a result, the highest dielectric constant was observed at a Ti doping concentration of 2.5% because it enhances the crystallinity of ZrO. Excessive Ti doping hinders crystal formation.

One-Pot Facile Synthesis of ZrO2-CdWO4: A Novel Nanocomposite for Hydrogen Production via Photocatalytic Water Splitting

ZrO2-based nanocomposites are highly versatile materials with huge potential for photocatalysis. In this study, ZrO2-CdWO4 nanocomposites (NC) were prepared via the green route using aqueous Brassica rapa leaf extract, and its photocatalytic water-splitting application was evaluated. Brassica rapa leaf extract acts as a reducing agent and abundant phytochemicals are adsorbed onto the nanoparticle surfaces, improving the properties of ZrO2-CdWO4 nanocomposites. As-prepared samples were characterized by using various spectroscopic and microscopic techniques. The energy of the direct band gap (Eg) of ZrO2-CdWO4 was determined as 2.66 eV. FTIR analysis revealed the various functional groups present in the prepared material. XRD analysis showed that the average crystallite size of ZrO2 and CdWO4 in ZrO2-CdWO4 was approximately 8 nm and 26 nm, respectively. SEM and TEM images suggested ZrO2 deposition over CdWO4 nanorods, which increases the roughness of the surface. The prepared sample was also suggested to be porous. BET surface area, pore volume, and half pore width of ZrO2-CdWO4 were estimated to be 19.6 m2/g. 0.0254 cc/g, and 9.457 Å, respectively. PL analysis suggested the conjugation between the ZrO2 and CdWO4 by lowering the PL graph on ZrO2 deposition over CdWO4. The valence and conduction band edge positions were also determined for ZrO2-CdWO4. These band positions suggested the formation of a type I heterojunction between ZrO2 and CdWO4. ZrO2-CdWO4 was used as a photocatalyst for hydrogen production via water splitting. Water-splitting results confirmed the ability of the ZrO2-CdWO4 system for enhanced hydrogen production. The effect of various parameters such as photocatalyst amount, reaction time, temperature, water pH, and concentration of sacrificial agent was also optimized. The results suggested that 250 mg of ZrO2-CdWO4 could produce 1574 µmol/g after 5 h at 27 °C, pH 7, using 30 vol. % of methanol. ZrO2-CdWO4 was reused for up to seven cycles with a high hydrogen production efficiency. This may prove to be useful research on the use of heterojunction materials for photocatalytic hydrogen production.

Computer Modeling of Plasma-Enhanced Atomic Layer Deposition of HfO2 and ZrO2

Computer Modeling of Plasma-Enhanced Atomic Layer Deposition of HfO2 and ZrO2

Microzone characterization and corrosion resistance of water-based epoxysilane/Ti/Zr composite chemical conversion coating on multi-metals

A water-based epoxy silane and titanium/zirconium composite chemical conversion coating was prepared on the surfaces of 6061 aluminum alloy, 7075 aluminum alloy, and galvanized steel simultaneously. Our findings revealed that the composite chemical conversion coating exhibited the strongest anti-corrosion effect on multi-metals surfaces as the concentration of silane was 0.4 vol% and the conversion time was 90 s. The analysis showed that a notable deposition of TiO2 and ZrO2 in close proximity to intermetallic compounds, segregation phases enriched with copper, and inclusions. Notably, the formation of the composite chemical conversion coatings on the multi-metals surface primarily follows a synergistic mechanism involving adsorption, oxidation, and readsorption. Consequently, a crosslinked siloxane network structure is formed, which offers additional filling sites for surplus particles of Al2O3, TiO2, ZrO2, and Fe2O3.

Towards modeling of ZrO2 atomic layer deposition at reactor scale based on experimental kinetic approximation

In this study, the growth kinetics of ZrO2 via the atomic layer deposition (ALD) using a mixed alkylamido-cyclopentadienyl zirconium precursor are proposed based on experimental data to evaluate the film growth behavior using reactor-scale simulation. In the ALD process, the hydroxyl concentration on the targeted surface govern the saturated growth per cycle values. However, we found that the bulkiness of remaining ligands on adsorbed species hinders the adsorption of Cp-Zr molecules.Considering this phenomenon, we proposed a kinetic model by calculating the energetic terms to quantify the “steric hindrance effect” of the first elementary surface reaction of CpZr(N(CH3)2)3 precursor (Cp-Zr), which enables the film growth prediction with the reactor-scale computational fluid dynamic (CFD) model.According to the experimental ALD process, the film growth was found to be influenced by the steric hindrance factor, especially at the temperature range from 150 °C to 250 °C, but the hindrance effect decreases with increasing temperature and disappears at 300 °C. The effective activation energy of the adsorption of Cp-Zr molecules on Si substrate was estimated to be 0.175 eV. Further understanding of the kinetic of ZrO2 deposition in this study is estimated to contribute to the optimization of the high-k metal oxides ALD deposition processes.

Reaction mechanism and film properties of the atomic layer deposition of ZrO2 thin films with a heteroleptic CpZr(N(CH3)2)3 precursor

The surface reaction of a heteroleptic precursor in the atomic layer deposition (ALD) of ZrO2 has been investigated using atomically thin films for scaled-down semiconductor devices. Heteroleptic precursors have been widely used in ALD. Because different ligands in heteroleptic precursors have different reaction pathways, understanding the surface reaction is crucial. In this study, we investigate the growth mechanisms of thin films using a CpZr(N(CH3)2)3 precursor with different reactants, such as H2O and O2 plasma. Chemical composition, surface roughness, film density, and microstructures were analyzed through electron microscopy and X-ray techniques together with quantum chemical calculations to elucidate the ZrO2 growth mechanism. The results showed that the reaction pathway of Zr–Cp ligand exchange with surface hydroxyl groups is less favorable than the Zr–N(CH3)2 reaction pathway. Furthermore, H2O molecules showed less effective oxidation reactions with Cp ligands than with alkyl amide ligands. In contrast, all the ligands were completely removed, resulting in negligible impurity incorporation, as revealed via X-ray photoelectron spectroscopy, when O2 plasma was used, leading to an improved leakage current (30-fold reduction). We believe that these findings on the surface reactions of heteroleptic ALD precursors will be helpful for developing future scaled-down semiconductor devices.

Plasma enhanced chemical vapour deposition of ZrO2 and YSZ coatings

YSZ coatings can prevent deleterious thermal effects on thermolabile alloys, however, a challenge is their deposition with a cubic phase at temperatures below 800 °C. In this work, PE-CVD was used to deposit ZrO2 and YSZ coatings at ∼700 °C, by varying the evaporation temperature, the vol.% O2, and the substrate position. Our results showed that an evaporation temperature of 200 °C was needed to deposit ZrO2 coatings. At 700 °C, the tetragonal phase was favoured regardless of the position within the heating zone. At 800 °C with a content of 20–60 vol.% O2, monoclinic and tetragonal structures were predominant, probably due to an increase in the crystallite size. When the ZrO2 was dopped with Y2O3, a fully cubic structure of ZrO2 was deposited.

Nitrogen doped ZrO2 thin films: synthesis and characterization

To obtain ZrO2 and ZrO2+N2 thin films was used magnetron sputtering in radio frequency mode in a 10-6 mbar high vacuum deposition chamber. Silicon and carbon substrates measuring 12x15mm were used for deposition. The used magnetron system was composed of a single water-cooled cathode, provided with one circular targets of ZrO2 (2 mm thick and 50 mm in diameter) of high purity (99.95%). TDS Analysis of the films was performed. The desorbed species were observed with a QMG 220 Mass spectrometer provided with a W filament. It can be observed that in the case of the ZnO2 film, nitrogen desorption registers two maxima with signal intensity of 9.7x10-12 and 9.0x10-12, reached after 2000s and 4900s respectively. In the case of ZrO2+N2 film, nitrogen desorption shows a pronounced maximum with a signal intensity of 2.4x10-11 reached after 6000s. . The topology the ZrO2 and ZrO2+N2 samples deposited on Si substrates have been investigated by scanning electron microscopy (SEM) using a FEI Inspect S scanning electron microscope ( Hillsboro, Oregon, OR, USA) in high-vacuum modes. For the ZrO2 deposition, the surface appears to have grain-like topology, with a mean dimension of around 150 nm. These structures do not appear for the ZrO2+N2 deposition. Instead, for the ZrO2+N2 sample, small blisters (between 300 nm and 1.000nm) have formed on the surface, as a consequence of injecting N2 during the deposition. Cross-section measurements were also performed to establish the layer thickness. The ZrO2 sample has a measured thickness of 1950nm, while the introduction of N2 gas for the ZrO2+N2 sample had a poisoning effect on the magnetron target that led to a decrease (5 times) in deposition rate, giving this sample a final thickness of 365nm (compared to 1950nm) for the same deposition The crystalline structure was investigated using X-Ray Diffraction (XRD) method. The experimental set-up was composed of a diffractometer equipped with a Cu-Kα X-ray sourse, with a specific wavelength of 0.154nm, in a Bragg-Bretano type geometry. In this way, a crystalline phase corresponding to ZrO2 with a group symmetry Fm-3m (225)-face centered cubic was identified. At the same time, it is observed that the films deposited in the reactive atmosphere show a pronounced amorphization, this most likely being due to the retention of nitrogen which leads to the modification of the network parameters.

Effect of ZRO2 and Y2O3 Deposition on Biological Behavior of Ti-Base Alloys

Titanium has a good ability to attach to bone and living tissue, making it a perfect material for orthopedic implants. Because of the combination of high resistance to corrosion, biocompatibility and excellent mechanical properties. This work aims to study the Modifications of various base titanium implant samples producing by using powder technology (Ti-pure, Ti-45 % Ni, Ti10 % Co, and Ti-30 % Ta) by deposition of Nano Zirconia and yttria powders (70 % and 30% ). Chemical pretreatment carried out to prepare the implant surface before deposition, while the deposition process accomplished by pack cementation. The Characterizations of samples accomplished before and after the surface treatment, which includes: microstructure observation, x-ray diffraction (XRD), MTT Assay (cell viability) and MTT assay (cell adhesion). From the SEM All samples Show that Nano Zirconia and yttria were homogeneously put on the surface and fully covered it which resulted in a substantial modification in surface morphologies. From XRD patterns the peaks slightly shifted to the low angle side also amorphous behavior was observed. From MTT graphs it was found that the titanium alloys surface after pack cementation became more active after 3 days of exposure in MG-63 cells and there was a remarkable increase in cell viability and cell attachment compared with untreated samples.

Mechanism for growth initiation on aminosilane-functionalized SiO2 during area-selective atomic layer deposition of ZrO2

The mechanism for growth initiation on the nongrowth surface during area-selective atomic layer deposition (ALD) processes is not well understood. In this study, we examine the ALD of ZrO2 on a SiO2 surface functionalized with alkylated-aminosilane inhibitors delivered from the vapor phase. ZrO2 films were deposited by ALD using tetrakis(ethylmethylamino)zirconium(IV) with H2O as the coreactant. In situ surface infrared spectroscopy shows that aminosilane inhibitors react with almost all the surface —SiOH groups on the SiO2 surface by forming Si—O—Si bonds. In situ four-wavelength ellipsometry shows that no ZrO2 growth occurs on the functionalized SiO2 during the first few ALD cycles, but growth eventually initiates after a few ALD cycles. We speculate that after repeated exposure of the functionalized SiO2 surface to Zr precursors, in the absence of surface —SiOH groups, growth initiates due to either reaction of the precursors with strained Si—O—Si bonds or through a strongly physisorbed state. These reaction pathways are usually not relevant in ALD reactions on the unprotected —SiOH-terminated SiO2 surface due to a higher activation energy barrier, but become relevant on the passivated surface as a result of repeated precursor exposure. Thus, this study highlights the importance of steric blocking of these higher activation energy barrier reaction pathways.

Microstructural Analysis and Tribological Behavior of Ti-Based Alloys with a Ceramic Layer Using the Thermal Spray Method

The present article focuses on a recently developed new system of alloys (Ti15MoSi) coated with ZrO2. The thin coatings deposition of ZrO2 on titanium alloys can be a solution to improve their corrosion resistance, biocompatibility, and to extend their long life with the human tissue. In order to improve the corrosion resistance, atmospheric plasma spraying coatings with zirconia have been performed. These coatings present a homogenous aspect with very few cracks. The novelty of the research is that zirconia is much stable in the simulated body fluids and presents no harm effects to the healing process of the bone. To analyze the thin coatings deposition, mechanical properties, chemical structure, and corrosion resistance were examined by a modulus of elasticity, X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), and linear polarization. The results reveal that Young’s modulus shows a low value (51 GPa for Ti15Mo0.5Si-ZrO2 and 48 GPa for Ti15Mo-ZrO2) and the XRD patterns show the presence of β-Ti and ZrO2 phases having a tetragonal crystalline structure. The research highlighted the morphological aspect of zirconia coatings on the new alloy titanium substrate, being an adherent compact coating with significantly improved corrosion resistance. Moreover, the mechanical properties are similar to the biological bone, which will avoid the stress shielding of the implant with bone tissue.

Improved performance and stability of low-temperature, molten-carbonate fuel cells using a cathode with atomic layer deposited ZrO2

Molten-carbonate fuel cells (MCFCs) are high-temperature fuel cell systems that typically operate at approximately 650 °C. Due to their high operating temperature, the thermal degradation of MCFC components limits the lifetime of the MCFC. Therefore, lowering the operating temperature is an effective way to reduce thermal degradation. However, the electrochemical reaction on the cathode also becomes slower as the operational temperature decreases. To improve the performance and stability, atomic layer deposition (ALD) of ZrO2 on the cathode is proposed. ALD produces a uniform, thin coating with precise thickness control. Therefore, nano-coating can be performed via ALD without affecting the porous structure of the cathode. The uniform ZrO2 coating donates electrons to NiO due to the low electronegativity of Zr. The electron-rich environment of NiO improves the cell performance by providing electrons for the oxygen reduction reaction. Also, the single cell using ZrO2-coated cathode demonstrates improved stability compared to the uncoated cathode cell due to the inhibition of NiO sintering by the ZrO2 coating layer.

The Effect of Atomic Layer Deposition of ZrO2 on the Cathode on the Performance of Molten Carbonate Fuel Cell

Molten carbonate fuel cell (MCFC) is a high-temperature fuel cell for power plants. Since MCFC is operated at approximately 650 °C, the lifetime of the MCFC is limited by the thermal degradation of MCFC components. To reduce thermal degradation, the lower temperature for long-term operation is suggested. However, the electrochemical reaction on the cathode becomes slower at the lower operational temperature. To improve the performance for the long-term operation of MCFC, a ZrO2 coated cathode was fabricated by atomic layer deposition. The cell using the ZrO2 coated cathode showed a high voltage of 0.867 V at a temperature of 600 °C and a current density of 150 mA/cm2. The charge transfer resistance is also reduced dramatically at that same time. It can be confirmed that the high cell performance is presented when the electron-rich environment of NiO by ZrO2 coating improved the performance of the cell. Also, the cell using the ZrO2 coated cathode kept a stable performance over 2,000 h due to the prevention of NiO sintering by the uniform ZrO2 coating layer.

Zr-based conversion coating on Zn and Zn-Al-Mg alloy coating: Understanding the accelerating effect of Cu(II) and NO3−

The reactivity of a Zn-Al-Mg galvanized steel substrate was monitored during a two-step conversion coating sequence with an alkaline pretreatment followed by conversion coating with hexafluorozirconic acid (H2ZrF6). The main effect of alkaline pretreatment was to remove initial oxides and to selectively dissolve Al, limiting the dissolution of Al in the zirconate bath. The commercial alkaline cleaner dissolved Mg from the MgZn2 intermetallic phase. The effect of NO3− and Cu(II) on the reactivity of a commercial Zn-Al-Mg alloy coating was investigated in H2ZrF6, simulating a Zr-based conversion coating process. NO3− served as an oxidant which enhanced the production of OH− leading to a more consequent ZrO2 deposition. Cu(II) underwent a displacement reaction with Zn (0) to form Cu(0) which catalyzed the reduction of NO3− and H+. The interplay between activation and passivation was demonstrated by the occurrence of oscillations in the both NO3− and Cu(II) containing electrolyte under certain conditions.

Distributed Feedback Lasers Based on Green Fluorescent Protein and Conformal High Refractive Index Oxide Layers

AbstractFluorescent proteins have emerged as an attractive gain material for lasers, especially for devices requiring biocompatibility. However, due to their optical properties, integration with distributed feedback (DFB) resonators is not readily achievable. Here, a DFB laser with enhanced green fluorescent protein (eGFP) as the gain material is demonstrated by incorporating a thin (65 nm), high refractive index (n = 2.12) ZrO2 interlayer as waveguide core. Deposition of ZrO2 via atomic layer deposition yields a smooth and conformal film as required to minimize optical losses. Lasing emission is obtained from 2D second‐order DFB eGFP lasers at pump power densities above 56.6 kW cm–2 and a wavelength tuning range of Δλ = 51.7 nm is demonstrated. Furthermore, it is shown that in contrast to conventional organic DFB lasers, both transverse electric (TE) and transverse magnetic (TM) modes are accessible. The effective refractive index of these modes can be predicted accurately through optical modelling. Using far‐field imaging, the laser beam profile is studied and TE and TM modes are distinguished.

Development of ZrO2 and YSZ coatings deposited by PE-CVD below 800 °C for the protection of Ni alloys

One possibility to increase the safety of structural Ni alloys is the use of yttria stabilized zirconia coatings in order to avoid deleterious thermal effects on their mechanical properties and corrosion resistance above 800 °C. However, the deposition of YSZ with a fully cubic structure below 800 °C cannot be achieved by traditional processing routes. In this work, we show the deposition of ZrO2 and Y2O3-stabilized ZrO2 coatings by Plasma Enhanced Chemical Vapor Deposition (PE-CVD). To this purpose, the effect of deposition temperature (500–800 °C), plasma power (50–250 W) and precursor concentration (0.5–2 g) on the microstructure, composition and crystalline phase of ZrO2 and YSZ coatings was studied. Contrary to previous reports, we show that it is feasible to use zirconium (IV) acetylacetonate [Zr (acac)4] to produce nanostructured zirconia coatings with low carbon content (1.8 at.%) and metastable tetragonal phase. A fully cubic YSZ structure was achieved with the use of Y-acetylacetonate with concentrations above 12 mol% at 700 °C and obtain a columnar microstructure.