Grazing Incidence Angle X-ray Diffraction Research Articles

Wetting behavior of stainless-steel surface with zinc oxide nanorod coatings: modulations in nanorod alignment through atomic layer deposition

This study investigated the hydrophobic-hydrophilic characteristics of zinc oxide (ZnO) nanorod coatings for potential biomedical applications. We examined the effects of different alignments of ZnO nanorods on the wetting and mechanical characteristics of the coatings. ZnO seed layers were prepared on stainless-steel plates using atomic layer deposition (ALD) at five different temperatures ranging from 50 to 250 °C. The ZnO nanorod coatings were then deposited on these seed layers through chemical bath deposition. The polycrystalline structure of the seed layers and the morphology of the nanorods were analyzed using grazing incidence angle x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical and wetting properties of the nanorod coatings were examined using nanoindentation and water-droplet tests. The seed layers produced at 50 and 250 °C showed stronger (0 0 2) peaks than the other layers. ZnO nanorods on these seed layers exhibited greater vertical orientation and lower water contact angles indicating a more hydrophilic surface. Additionally, vertically oriented nanorod coatings demonstrated greater elastic modulus and hardness than those of oblique nanorods. Our findings indicate that ALD technology can be used to control the spatial arrangement of ZnO nanorods and optimize the hydrophobic-hydrophilic and mechanical properties of coating surfaces.

Stability of titanium deuteride films irradiated with pulsed ion beams

Titanium deuteride films are widely used as target materials for neutron generators. Intense pulsed ion beams irradiated titanium deuteride films, and their structure stabilities were investigated by combination with scanning electron microscopy, transmission electron microscopy, grazing incidence angle X-ray diffraction, slow positron beam, scratch test and finite element analysis. The beam energy density was 0.3 J/cm2. Five different irradiation fluences of 3 × 1014, 1 × 1015, 3 × 1015, 1 × 1016, 3 × 1016 cm−2 were performed at room temperature. The adhesion strength between the film and Mo substrate decreased with increasing fluence. Moreover, surface melting and grain growth occurred after the beam irradiation with fluences over 3 × 1015 cm−2. The morphology of scratch tracks shows that the titanium deuteride film suffers a transition from ductile fracture to brittle fracture with increasing fluence. The reason for the decreasing adhesion strength was discussed via the introduction of thermal stress and lattice structure recovery. The research result is critical for evaluating the lifetime of titanium deuteride films based on failures in structures and a decrease in concentration of the inner deuterium.

Stress Effects of Interconnecting Metals on Back-End-of-Line Compatible Hf0.5Zr0.5O2 Ferroelectric Capacitors

The back-end-of-line (BEOL) process compatibility is one of the advantages of Hf0.5Zr0.5O2 (HZO)-based ferroelectric (FE) among other kinds of HfO2-doped FEs. However, the impact of stress effect induced by the interconnects during device stacking cannot be ignored. Previous studies about the stress effect have mainly focused on the metal in direct contact with the FE layer, but have neglected the potential effects of other layers covering the electrodes. In this work, the stress effects of interconnecting metals including Cu and W, which are the most mainstream interconnects in modern integrated circuit (IC) technology, are systematically demonstrated. The capping layers can exert stress on the top electrode (TE), and this stress transfers to the HZO layer during annealing, which affects the crystalline state of HZO films and enhances or suppresses the ferroelectricity. This is verified by the devices’ electrical performance, the residual stresses measurements and grazing-angle incidence X-ray diffraction results. The results can guide the selection of the proper annealing timing for large-scale FE memory integration when utilizing the BEOL process with different interconnects.

Growth characteristics and properties of RuAlO hybrid films fabricated by atomic layer deposition

In this work, RuAlO hybridfilmswere synthesized by alternating ALD sequences of Al2O3and Ru for electrical conductivity regulation.O2exposure has significant effectson the nucleation and etching processes of Ru, therefore the O2exposure was first optimized for efficient growth of Ru. A set of RuAlOhybrid films with different Ru subcycle ratioswere fabricated.In-situ quartz crystal microbalance (QCM) measurementrevealed acertain nucleation delaywhenRu was deposited on the surface ofAl2O3, whileno nucleation delay was observed when Al2O3was deposited on Ru. High resolution transmission electron microscopy(HRTEM) characterization confirmed formation ofRu grains embedded in amorphous Al2O3matrix. Elemental mapping results demonstrated that RuandAlelementsareuniformly distributedon the cross section ofthe film.In the grazing incidence angle X-ray diffraction (GIAXRD) patterns ofRuAlOhybrid films,characteristic diffraction peaks of Ru appear with aRusubcycle ratio ≥ 70 %. By properly tuning the Ru to Al2O3ALD subcycle ratio, electrical resistivity of theRuAlOhybrid film could beadjusted over a wide range of 10-3 ∼ 1011Ω·cm.

Ultra-low Young's modulus Zr-Nb thin films on Mg substrate for enhanced corrosion resistance

Controlling the degradation rate of magnesium (Mg) via applying the (Zr-Nb) thin films was investigated in this study. The Zr-2.5Nb coatings were deposited on the Mg with thicknesses of 250, 450, 650, and 900 nm (hereafter named [email protected], [email protected], [email protected], and [email protected]), respectively. Grazing incidence angle X-ray diffraction of (Zr-Nb) coatings revealed the alpha phase of zirconium and dominant (002) texture, with the film thickness increasing from 450 nm to 900 nm. Potentiodynamic polarization, electrochemical impedance spectroscopy, and corrosion morphology observations in Dulbecco's Modified Eagle's cell culture medium (DMEM) solution revealed the (Zr-2.5Nb)-coated mg with the thickness of [email protected] sample provides the highest corrosion resistance compared to other studied thicknesses. [email protected] sample increases the corrosion potential from −1.49 V to −1.38 V and decreases the current corrosion density and corrosion rate from 149.32 (μA.cm−2) to 39.01 (μA.cm−2) and from 3.49 (mm.y−1) to 0.912 (mm.y−1), respectively. Further studies on the surface of the [email protected] sample in terms of nano-mechanical properties demonstrated that Young's modulus and hardness are 47.95± 4.43 GPa and 2.25± 0.41 GPa, respectively, which increases the hardness to reduced Young's modulus ratio, which is known as one of the important parameters in developing of temporary orthopedic implants, of the Mg from 0.03 to 0.06. Furthermore, nano-tribological measurements and atomic force microscopy observations confirmed that detachment or breakage are not observed. Zr-2.5Nb coating, owing to the influence only on the first stage of the degradation reduced the degradation rate of Mg surafce, and therefore, can be considered as a practical strategy for further development of Mg in orthopedic applications.

Raman Spectroscopy as a Key Method to Distinguish the Ferroelectric Orthorhombic Phase in Thin ZrO2‐Based Films

Inducing and detecting the polar orthorhombic phase are crucial for the establishment of ferroelectricity in HfO2‐ and ZrO2‐based thin films. Unfortunately, commonly used structural characterization techniques such as grazing incidence angle X‐ray diffraction (GIXRD) only partially allow an accurate detection of this crystalline phase, whose characteristic pattern almost coincides with the one of the tetragonal phase. As a consequence, phase determination is commonly based on peak deconvolution tracing the position of the main peak at 2θ values of around 30°, which can be assigned both to the t(101) and the o(111) plane directions and additionally be influenced by mechanical stress in the layers. Alternatively, epitaxial layers are required to differentiate the phase. Herein, using an integrated experimental–computational approach, it is shown how Raman spectroscopy can distinguish between the monoclinic, the tetragonal, and the orthorhombic phase of ZrO2. The Raman spectra calculated from first principles match the experimentally measured data and thus enable an unambiguous phase assignment. Therefore, Raman spectroscopy proves to be a powerful technique for discerning the three main crystalline phases in these materials. As demonstrated by the good agreement between structural and electrical data, it can therefore be used to predict ferroelectricity in the addressed layers.

Enabling large ferroelectricity and excellent reliability for ultra-thin hafnia-based ferroelectrics with a W bottom electrode by inserting a metal-nitride diffusion barrier

Metal-nitride layers were used as tungsten (W)-diffusion barriers for ultra-thin (<5 nm) Hf0.5Zr0.5O2 (HZO)-based ferroelectric capacitors with W as the bottom electrode. The influence of various metal nitrides (e.g., TiN, HfN, and ZrN) on the leakage properties, ferroelectricity, and reliability of the HZO capacitors was systematically investigated to identify appropriate materials for use as diffusion barriers in TiN/HZO/W stack capacitors. All the metal-nitrides were observed to significantly suppress W diffusion, resulting in a reduced leakage current. A comparative study between diffusion barriers revealed that the TiN/HZO/W stack capacitor with a ZrN layer exhibited the largest remanent polarization (2Pr) of 23 μC/cm2, as well as the highest reliability. This was attributed to the ZrN forming a ZrO2 interfacial layer, which could contribute to polarization switching and improve reliability. We quantitatively calculated the interfacial capacitance by performing the pulse switching measurement. In addition, crystal structures and diffusion properties with various metal nitrides are evaluated by analyzing grazing-angle incidence x-ray diffraction and x-ray photoelectron spectroscopy. These results provide a guideline for the fabrication of ultrathin HZO-based capacitors with stable ferroelectricity, reduced leakage, and excellent reliability.

Plasma-assisted template removal and consolidation of silica coatings on polycarbonate

This paper presents a fast and efficient method of removing the template from silica thin films on polycarbonate. Radiofrequency-generated oxygen plasma induced the decomposition of the non-ionic surfactant. The reference samples were silica coatings on silicon, which had different pore sizes. We removed the surfactant by solvent extraction and calcination from these samples. Grazing incidence angle X-ray diffraction analysis shows a highly ordered arrangement of mesopores. The formation of the face-centred cubic structure of mesopores is independent of the substrate and the template removal method. Atomic force microscopy analysis showed open-pore channels after oxygen plasma etching. It also proved that the ammonia treatment increases the hardness of the layer. A short air-plasma treatment is effective for the consolidation of the silica layer and improves the abrasion resistance of the layer on polycarbonate. Air plasma treatment is an alternative to the long heat treatment process. We performed environmental tests according to the relevant ISO standards for optical coatings. Air plasma treated silica coatings have passed all the weathering tests. Therefore, it can be used in outdoor applications, such as a protective layer for the plastic cover of LED street lights. These thin films on polycarbonate have at least one year of service life and are weather-resistant. Plasma treatment can consolidate the silica network and the thin films on polycarbonate have high light transmission (T = 98.8 %).

The microstructure and tribological properties of M50 steel surface after titanium ion implantation

Titanium ions with different energies and doses were implanted into the M50 steel surface. In addition, titanium and nitrogen ion co-implantation was applied for comparison. The tribological properties and wear resistance of the implanted samples were characterized using a sliding friction tester, grazing incidence angle X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, surface profiler, Raman spectrometer, and nanoindentation tests. The results indicated that the compounds of the titanium ion–implanted samples mainly consisted of titanium and TiO2, CrN interstitial compounds formed after titanium and nitrogen ion co-implantation, thus generating an implantation layer that exhibited high nano-hardness and low wear rates. The linear contact sliding friction coefficient curves for the implantation samples were composed of an initial stage, ascent stage, and stable stage. The tribological properties effectively improved with increasing titanium ion implantation energies and doses. In addition, this beneficial effect became much more significant at a higher titanium ion dose. The titanium and nitrogen ion–co-implanted samples formed Fe2O3 and Fe3O4 tribo-oxide layers after the wear test, which were partially responsible for reducing the wear. The dominant wear mechanisms of the implanted samples were abrasive wear and oxidative wear.

Heavy ion irradiation induced defects in Zircaloy-4

Radiation damage induced in Zircaloy-4 by 20 MeV Au ions was investigated using Grazing x-ray diffraction (GIXRD), positron annihilation techniques, micro-and nano-hardness techniques. The irradiations were performed at room temperature in the fluence range 1 × 1013–5 × 1014 ions cm−2 corresponding to 0.07–3.63 displacements per atom (dpa). The grazing incidence angle x-ray diffraction (GIXRD) revealed the presence of the hydride precipitates in the analyzed zircaloy-4. According to our experimental data it is found that the amount of these precipitates decreases after irradiation as emphasized by GIXRD and Positron Annihilation Lifetime Spectroscopy (PALS) results. The same data revealed also a zircaloy-4 swelling above a certain dose. From the combination of domain size/microstrain with the micro- and nano-hardness results, we conclude that the Zircaloy hardening is mainly due to the dislocation formation indicating the effect of the microstructure on the mechanical properties. Moreover, from the dose dependence of irradiation hardening we conclude that the transition point from low-dose to high-dose regime is observed around 0.07 dpa.

Ultra-thin Hf0.5Zr0.5O2 thin-film-based ferroelectric tunnel junction via stress induced crystallization

We report on 4.5-nm-thick Hf0.5Zr0.5O2 (HZO) thin-film-based ferroelectric tunnel junctions (FTJs) with a tungsten (W) bottom electrode. The HZO on the W electrode exhibits stable ferroelectricity with a remanent polarization of 14 μC/cm2, an enhanced tunneling electroresistance of 16, and excellent synaptic properties. We found that a large tensile stress was induced on a HZO thin film, owing to a low thermal expansion coefficient of the W bottom electrode. The low thermal expansion coefficient results in the effective formation of an orthorhombic phase, even in an ultra-thin HZO film. This was verified by a comparative study of the electrical characteristics, grazing-angle incidence x-ray diffraction, and residual stress measurement of the HZO film on various bottom electrodes with different thermal expansion coefficients. In addition, this study demonstrates the suitable functions of the FTJ for electronic synapses, such as analog-like resistance transition under various pulse schemes. The fabricated stress-engineered FTJ exhibits an appropriate conductance ratio, linearly modulated long-term potentiation and depression characteristics, and excellent reliability. These characteristics render FTJs ideal electronic devices for neuromorphic computing systems.

Influence of annealing conditions on tripe-layer TiO2/Si3N4/SiO2 antireflection coatings for GaAs solar cells

In this work, TiO2/SiO2/Si3N4 triple-layer antireflection coatings (TLARC) were prepared on GaAs substrate by RF sputtering and Plasma Enhanced Chemical Vapor Deposition (PECVD). Influence of annealing conditions on the structure and optical properties of TLARC were also investigated. The structure and optical proprieties were analyzed by Grazing Incidence Angle X-ray Diffraction (GIXRD) Fourier Transform Infrared Spectroscopy (FT-IR), Atomic Force Microscopy and UV-VIS spectroscopy. The experimental results were summarized as follows: diffraction peaks of SiO2, Si3N4 and TiO2 respectively appeared in the as-deposited status, and after annealing, new diffraction peak at 25.2° corresponds to TiO2 was confirmed by checking out PDF cards; Stretching vibration of Ti=O, Si-O-Si and N-Si-N was confirmed by FT-IR spectrum; The average reflectance of the TLARC after annealing at 750 °C and holding for 5 min reached the lowest value, which was approximately 7.84 %.

Structural evolution of Lu2‐xCexTi2O7 pyrochlores under 400 keV Ne irradiation

AbstractLu2‐xCexTi2O7 (LCTO) pyrochlores were irradiated by 400 keV Ne2+ with fluences (dose) of up to 5 × 1015 ions/cm2 (1.875 dpa). The detailed damage process was investigated by combining grazing incident angle X‐ray diffraction (GIXRD) and transmission electron microscopy (TEM). Subsequent to the 2% volume swelling at a fluence of 1 × 1014 ions/cm2 (0.037 dpa), the initially swollen LCTO pyrochlore formed both a disordered fluorite phase and a nanocrystalline pyrochlore phase at a fluence of 5 × 1014 ions/cm2 (0.185 dpa). At higher fluences, the fluorite phase diminished as amorphous domains increased in volume when the dose reached a fluence of 1 × 1015 ions/cm2 (0.371 dpa), while the nanocrystalline pyrochlore phase persisted. At the highest fluence of 5 × 1015 ions/cm2 (1.854 dpa), the amorphous fraction decreased, meanwhile the degree of crystallinity of nanocrystalline pyrochlore phase was enhanced, as evidenced by the increased intensity of superlattice diffraction maxima. The phase transformation and recrystallization can be explained by the release of strain in irradiation‐induced swollen pyrochlore crystallites. The evolution of the damage process is mainly driven by the differences in the Gibb's free energies of fluorite phase as compared with the pyrochlore phase as a function of grain size. We have demonstrated that ion beam techniques can be used to manipulate the phase stability and crystallite size of pyrochlore. These results provide the basis for tailoring the mechanical strength and response of pyrochlores to extreme radiation environments.

Evolution of crystallographic structure and ferroelectricity of Hf0.5Zr0.5O2 films with different deposition rate

Hf0.5Zr0.5O2 films are one of the most attractive HfO2-based ferroelectric films because of good ferroelectricity, extreme thinness, and excellent compatibility with silicon devices. The origin of the ferroelectricity of Hf0.5Zr0.5O2 films is the noncentrosymmetric orthorhombic phase (space group Pca21). The effects of process temperature, annealing temperature, thickness, and doping to increase the portion of the orthorhombic phase, which contributes to ferroelectricity, have been studied extensively. However, although most studies have used atomic layer deposition, no study has been reported on the effect of the deposition rate on the ferroelectricity of Hf0.5Zr0.5O2 films. In this work, the influences of the deposition rate on the ferroelectricity and crystal structure of Hf0.5Zr0.5O2 films were examined. In order to conduct systematic and quantitative analysis, measurements of switching transient current, ferroelectric P-E curve, dielectric constant, deconvolution of grazing angle incidence X-ray diffraction, and piezoresponse force microscopy were performed. Hf0.5Zr0.5O2 films with a deposition rate of 1.1 Å/cycle have a more ideal hysteresis curve shape, higher remanent polarization (initial state: 16 μC/cm2, wake up state: 22 μC/cm2), and a higher orthorhombic phase portion than other deposition rates.

Performance of Si/PEDOT:PSS Solar Cell Controlled by Dipole Moment of Additives

Solar cells composed of silicon (Si) and polymer films have attracted much attention because of their high performance and facile preparation using aqueous solutions. Although a large amount of research has been carried out to further improve their performance, the factors required to achieve this are not yet fully understood from the perspective of physical chemistry. Here, we show the effect of additives on the performance of Si/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solar cells using six different additives. The relationships among the solar cell performance, electrical properties, and the structure of the polymer film are examined by changing the additive and conducting cyclic voltammetry, electric conductivity, and two-dimensional grazing incidence angle X-ray diffraction measurements. The dipole moment of the additive molecule was determined to be a key factor for improving the performance of Si/PEDOT:PSS solar cells. In particular, an additive with a higher dipole momen...

Effects of deposition temperature on the properties of sputtered yttrium-doped hafnium oxide thin films

Yttrium-doped HfO2 (Y:HfO2) thin films with different deposition temperature were deposited on p-type (100) silicon substrates. The composition and chemical states of each element in the films were investigated by x-ray photoelectron spectroscopy (XPS). The grazing angle incidence x-ray diffraction (GIXRD) patterns suggested the phase transformation of Y:HfO2 thin films as the increase of deposition temperature. The thickness and density of the thin films were calculated by fitting x-ray reflectivity (XRR) data. Root mean square (RMS) roughness was obtained from atomic force microscopy (AFM) images. As the deposition temperature increased, a transition from linear dielectric to ferroelectric behavior happened. Lower leakage current density was obtained by increasing the deposition temperature.

Effect of neutron irradiation on the structural, electrical and optical properties evolution of RPLD VO2 films

This study reports on the effect of neutron irradiation at different fluences on the properties of VO2 thin films. The irradiations were performed at NUR research reactor, Algiers at a temperature of about 40 °C, with fast neutron fluence (En > 1 MeV) up to 1.9 × 1018 n.cm−2. The induced defects have been investigated using structural, optical and electrical measurements. Both bulk sensitive characterization techniques, Raman and grazing incident angle X-ray diffraction (GIXRD) analysis, show that no structural transformation is induced by neutron irradiation, although strain induced defect production are generated throughout the films while surface sensitive techniques, X-ray photoelectron spectroscopy (XPS) and work function measurements, show that the charge carrier (electron) concentration at room temperature decreases after irradiation. Potentially due to fast neutron irradiation induced defects, mainly in the form of Frenkel pairs, swelling and color center formation occurs in VO2 thin films without amorphization. This is further corroborated by an increase of the room temperature resistivity through the irradiated films. Temperature-dependent electrical and optical transmission measurements confirm that the characteristic semiconductor-to-metal transition of the VO2 films is preserved upon irradiation. We therefore conclude that VO2 is an excellent candidate for thermal shielding and thermal management of small satellites.

The influence of nitrogen to hydrogen ratio and temperature on thickness and phase composition in plasma nitrided Ti-6Al-4V

Ti-6Al-4V was plasma nitrided using several N2/H2 ratios and substrate temperatures. In order to investigate the combined influence of these parameters on phase composition and thickness of the coatings, the phases in the as received, annealed, and nitrided Ti-6Al-4V samples were identified with Rietveld refinement. In the as-received and annealed samples the structure parameters of -Ti and -Ti were slightly changed, due to the substitution of titanium atoms by Al or V in the - and -Ti unit cells. A combination of multiple angle grazing incidence X-ray diffraction, nuclear reaction analysis and cross sectional micrographs showed compound layers consisting of an outer layer of stoichiometric -TiN over a phase mixture of -TiN and -Ti2N, formed on top of a nitrogen diffusion region in the alloy. Higher nitriding temperatures induced thicker compound layers, and higher nitrogen content of the plasma induced thicker fine-grained -TiN top layers. Keywords: plasma nitriding, Ti-6Al-4V, titanium nitride, Rietveld analysis.

Oxidation resistance of a Mo-W-Si-B alloy at 1000–1300 °C: The effect of a multicomponent Mo-Si-B coating

The oxidation behavior and microstructures of a three phase Mo50W20Si15B15 alloy containing (Mo, W) solid solution, (Mo, W)5Si3 and (Mo, W)5SiB2 were investigated over the 1000–1300 °C temperature range. At 1300 °C, the alloy exhibited a large initial mass loss and eventually transitioned to a steady state behavior associated with the development of an amorphous borosilica scale. The oxidation resistance at lower temperature was unsatisfactory due to the pesting of Mo and W. Grazing Incident Angle X-ray Diffraction (GIXRD) measurements during the initial transient stage of oxidation identified the evolution of surface oxide products that were responsible for the large weight loss and pesting behavior. In order to address the large initial weight loss and the low temperature pesting behavior, the alloy was coated with a Mo-Si-B based coating by employing the pack cementation process followed by a conditioning treatment at 1450 °C. The microstructures of the coatings and the interlayer between the base alloy and the coating were studied, and the oxidation resistance of the coated alloys was evaluated over the 800–1300 °C temperature range. The coated alloy showed improved oxidation resistance with nearly zero mass change for extended period of time over the entire range of temperatures studied.

Facile method for decorations of Au nanoparticles on TiO2 nanorod arrays toward high-performance recyclable SERS substrates

High-performance recyclable SERS substrates with well-ordered hybrid nanostructure gold nanoparticles (Au NPs) decorated on titanium dioxide nanorods (TiO2 NRs) were successfully prepared by combining two methods. The TiO2 NRs were fabricated by electron-beam evaporation with glancing-angle deposition (GLAD) technique, then the Au NPs were decorated onto the TiO2 NRs surfaces by deposition-precipitation (DP). The physical structures of the obtained hybrid nanostructures were characterized by field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (TEM), and grazing incident angle X-ray diffraction (GIXRD). The results indicated that size and density of Au NPs on TiO2 NRs were controlled by HAuCl4 concentration for optimization of the SERS performance whose the detection of MB molecules was achieved at an enhancement factor of 6.5 × 107 with 9.76%-RSD at 1626 cm−1. More significantly, the optimized hybrid nanostructure SERS substrates exhibit excellent recyclability. These hybrid nanostructure SERS substrates were therefore promising towards detection of TNT for homeland security applications, as well as an on-site SERS platform.