TiN Layer Research Articles

Highly flexible superconducting films with metal-decorated composite 2D materials

Graphene forms an ideal platform to realize macroscopic hybrid materials by direct physisorption of electronically-active adsorbates on top of the high-mobility bidimensional (2D) gas of charge carriers. Here, we demonstrate a novel composite multilayer based on a thin polymer film covered with a monolayer of CVD graphene on top of which a thin layer of tin is evaporated. The metal film shows dewetting and forms a self-organized network of metal nanodots electronically coupled to the graphene. The resulting macroscopic multilayered structure is a highly flexible, stable, and processable composite 2D material that exhibits tunable superconductivity at low temperature. The superconducting properties of the macroscopic composite extend over the full sample size (several square centimeters) and are comparable to the ones of a mesoscopic array of Josephson junctions prepared with similar materials. It provides an upscaling of the concept that is useful for flexible electronics.

Microstructure investigation of textured CVD alumina coatings

This study concerns the interfacial microstructure and texture development in three textured CVD α-Al2O3 coatings using X-ray diffraction, transmission Kikuchi diffraction, scanning transmission electron microscopy and energy dispersive X-ray analysis. It is well known that the performance of these types of coatings relies on the degree and type of texture. The aim of this work is to study the microstructure of three different CVD α-Al2O3 layers when deposited onto a Ti(C,N,O) bonding layer. The coatings were deposited onto cemented carbide/cobalt substrates (WC/Co).It was observed that grain boundary diffusion of W and Co occurred through the TiN and Ti(C,N) layers to the bonding layer/α-Al2O3 interface. This may disturb the alumina layer nucleation and early growth. Interfacial porosity was observed at the bonding layer/α-Al2O3 interface. The number of voids that were detected in the (0001) and (011¯0)-textured coatings was similar when H2S was not used during the initial deposition step. When H2S was present during the nucleation step deposition of the α-Al2O3 more voids were introduced at the interface for the (0001)-textured samples. The alumina grain morphology developed from small (~100 nm) equiaxed grains at the start of the alumina coating to larger (several microns) columnar grains at the top of the coating. The inner part of the alumina coatings had a more random orientation. The texture changed either: (i) gradually over several grains, or (ii) more abruptly from one grain to another; from more random orientations to the desired texture. The desired texture develops earlier when using H2S at the start for the (0001)-textured coatings, while the (011¯0)-texture development benefits from the absence of H2S. Thus, in this study, H2S promotes (0001) texture and interfacial void formation.

Performance Enhancement of Ag/HfO2 Metal Ion Threshold Switch Cross-Point Selectors

A metal ion threshold switch (MITS) based on an Ag/TiN/HfO2/Pt stack is experimentally demonstrated with improved endurance. The incorporation of a low-temperature atomic layer deposition (ALD) TiN layer as an efficient diffusion barrier enables optimum Ag infiltration during the electroforming step. Further, the tunability of the threshold voltage (VTS) from 0.25 to 1.1V via bottom electrode (BE) work function engineering is demonstrated. The Ag/TiN/HfO2/Al MITS selector exhibits a 4.4x increase in VTS, $100~\mu \text{A}$ ON-current handling capability, low leakage (~10 pA), $10^{{7}}$ half-bias non-linearity and fast (<30 ns) turn-ON switching speed. The turn-OFF speed of the selector device is independent of the built-in field, indicating that the latter does not influence ionic relaxation during the filament rupture process.

Effects of hard TiN under layer on mechanical properties and wear characteristics of TiN-WSx composite coating

Effect of hard TiN underlayer on mechanical and wear characteristics of TiN-WSx composite coating was studied. A mono layer TiN coating was also incorporated in the study as a reference. The coatings were synthesized with pulsed magnetron sputtering process. Structural properties were investigated with field emission scanning electron microscopy, energy dispersive spectroscopy, grazing incidence x-ray diffraction; mechanical properties with scratch adhesion test, nanoindentation test and finally tribological properties were studied with pin-on-disc test. TiN underlayer resulted in a more compact morphology of top TiN-WSx hard-lubricious layer. WS2 phase with (002) orientation coexisted with crystalline TiN for TiN-WSx composite both with and without hard TiN underlayer. Scratch test revealed 35% increase in critical load of adhesion for TiN-WSx/TiN dual layer structure as compared to TiN monolayer. Brittle flaking of TiN along edges of scratch track also became negligible for dual layer coating owing to presence to soft WSx as well as presence of hard under layer which hindered substrate deformation during scratching. Low hardness of TiN-WSx as compared to TiN, partially recovered owing to addition of hard TiN underlayer. The dual layer coating also exhibited significantly low coefficient of friction of approximately 0.25–0.3 relative to 0.7–0.8 for TiN. The hard TiN underlayer reduced ploughing of top TiN-WSx composite layer. This in turn, resulted in low wear loss and subsequently less accumulation of wear debris at the leading edge of the counterbody.

Adaptive nematic liquid crystal lens array with resistive layer

ABSTRACTWe propose an adaptive nematic liquid crystal (LC) lens array using a dielectric layer with low dielectric constant as resistive layer. With the resistive layer and periodic-arranged iridium tin oxide (ITO) electrodes, the vertical electric field across the LC layer varies linearly over the lens aperture is obtained in the voltage-on state. As a result, a centrosymmetric gradient refractive index profile within the LC layer is generated, which causes the focusing behaviour. As a result of the optimisation, a thin cell gap which greatly reduces the switching time of the LC lens array can be achieved in our design. The main advantages of the proposed LC lens array are in the comparatively low operating voltage, the flat substrate surface, the simple electrodes, and the uniform LC cell gap. The simulation results show that the focal length of the LC lens array can be tuned continuously from infinity to 3.99 mm by changing the applied voltage.

Resistive Switching in Atomic Layer Deposited HfO2/ZrO2 Nanolayer Stacks

Resistive switching materials and devices have received unparalleled recent attention due their potential and demonstrated use as resistive random access memory (RRAM) and neuromorphic applications. Resistive switching or memristive materials can serve as two-terminal electrical components where the resistance is a function of the amount and direction of current previously experienced and therefore they can uniquely emulate biological synapse behavior. HfO2 is a well-known dielectric and memristive material that has been previously explored for RRAM applications. Here, to better understand the resistive switching in harfnia in the presence of insulating interfaces, the electrical properties of HfO2/ZrO2 nanolayer stacks are discussed. The stacks with total thickness of 16 nm were prepared on platinized Si substrates using atomic layer deposition (ALD). A capping layer of TiN (30 nm thick) and a Au top electrode (100 nm thick) were sputtered to complete the device. We will discuss the current-voltage behavior, pulse time mode measurements, retention and endurance tests of the devices. Resistive switching was observed in all multilayer samples, with the set voltage (Vset) decreasing with increasing number of layers (i.e., number of hafnia-zirconia interfaces). We will show that grazing incidence x-ray diffraction (GI-XRD) demonstrated the transition of the hafnia phase from monoclinic to orthorhombic structure during the post metallization annealing, and that shifts in the binding energy of the x-ray photoelectron spectroscopy spectra (XPS) imply the existence of hafnia suboxide (HfO2-δ). More importantly, we will show how memristive/insulating nanostructures like nanolayered HfO2/ZrO2 can help modulate the resistive switching of memristive-based devices, to include for example, a two-step electroforming process, and multistate resistive switching.

Optical, water splitting and wettability of titanium nitride/titanium oxynitride bilayer films for hydrogen generation and solar cells applications

TiN/TiOxNy bilayer films with various TiN thicknesses were prepared using direct current (d.c.) reactive magnetron sputtering. The ratio of N/O in the bilayer films increased with increasing TiN top layer thickness. The observed crystalline peaks for the bilayer films, for different TiN layer thicknesses, were indexed to anatase TiO2 with tetragonal structure. Only 0.31° peak shift, to lower 2θ angles was detected. FESEM indicated that the morphology of TiOxNy single layer is consisted of elongated nanocrystals with diameters in the range of 27.9–46.8 nm and the diameters of the nanocrystallites changed slightly with increasing the thickness of TiN layer. The transmittance, absorbance, reflectance spectra and the optical constants of the bilayer films were presented. The photoelectrochemical performance for water splitting of TiN/TiOxNy bilayer films was studied by examination both the continuous and chopped photocurrent density under light illumination. The photocurrent density increases with increasing TiN top layer up to a thickness of 9 nm, after which a reduction in photocurrent is observed. The wettability of TiN/TiOxNy bilayer films could be transformed by UV illumination from hydrophobic to hydrophilic.

Thermal shock resistance of TiN-, Cr-, and TiN/Cr-coated zirconium alloy

As a candidate technology for accident tolerant fuel (ATF), surface modified Zr cladding has captured the interest of an army of nuclear workers in the past few years. In this paper, three coatings (TiN, Cr, and TiN/Cr) were deposited on Zr-4 by direct current magnetron sputtering. The microstructural properties of the three coatings were detected by using scanning electron microscope (SEM) and X-ray diffraction (XRD). The thickness of coating was determined by examining the cross sectional SEM image. The adhesion properties of was characterized by using scratch testing. The thermal shock resistance (TSR) tests were carried out in three temperature variations, that is, △T = 800 °C, 1000 °C, and 1200 °C, respectively. After the TSR test, the surface morphology of the tested specimens was observed, XRD, SEM and energy dispersive spectrometer (EDS) were used to examine the microstructural properties of the tested specimens, and scratch testing was executed to determine the adhesion properties. The results show that TiN coating was partially peeled off and the inner zirconium alloy was oxidized. And the thickness of the generated ZrO2 layer is about 50 μm. The specimens coated with single Cr coating remained intact. The cross-sectional analysis result show that only about 30% of Cr coating is oxidized, and the residual Cr coating and inner zirconium alloy are not oxidized. It is mainly due to the dense and uniform structure of Cr2O3 formed by the oxidation of the outermost layer of Cr coating, which prevents the further penetration of oxygen into the interior and plays a very prominent protective role. For the bilayer TiN/Cr-coated specimens, the coefficient of thermal expansion (CTE) of intermediate TiN layer is different from that of zirconium alloy substrate. After TSR test, cracks and a large number of pores appear, and there are obvious gaps between the bulk oxidation products, which leads to poor protection of the internal materials. It indicates that the zirconium alloy coated with a single Cr coating has excellent TSR property.

Double-sided asymmetric surface modification of ZnO interfacial layer to enhance performance in organic solar cells

Surface modification of the widely used ZnO interfacial layer is a crucial issue for the development of photoelectric devices toward high efficiency and long-term stability. Most conventional surface modifications of ZnO interfacial layers involve only a one-sided modification (e.g., a ZnO/active layer interface), which limits the electrical and electronic performance of the resulting interfacial layer. Herein, we report a double-sided surface modification strategy in which both sides of the ZnO interfacial layer are modified. The resulting double-sided modified ZnO layers are used to enhance the photovoltaic performance of inverted organic solar cells as electron-transporting layers (ETLs). Compared with devices based on unmodified ZnO interfacial layers, the power conversion efficiencies of devices using the modified ZnO interfacial layer are markedly enhanced, from 3.42% to 4.23% for the P3HT:PC61BM active layer, and from 7.57% to 8.61% for the PTB7:PC71BM blend system. The enhancements in photovoltaic performance result mainly from the modified energy level alignment and improved interface contact quality between the ETL and active layer, which help to reduce the interfacial energy barrier between the active layer and indium tin oxide electrode, thereby enhancing the electron collection and transport efficiency. More importantly, this double-sided surface modification strategy could be easily extended to modify the interfacial layers of other photoelectric devices, such as perovskite solar cells, quantum dot solar cells and organic light-emitting diodes.

Investigation of nucleation and growth mechanism of bismuth electrodeposited on ITO substrate in nitric acid medium

Abstract Bismuth thin films were prepared on a glass substrate pre-coated with transparent and conducting layers of Tin doped indium oxide (ITO), kept at room temperature, by electrodeposition technique, using a an aqueous solution of nitric acid with a molar concentration of 1 mol L−1 and Bi(NO3)3, 5H2O as a source of bismuth. The cyclic voltammetry and chronoamperometry measurements revealed that the electrodeposition of bismuth (Bi) has been performed at a negative potential around −0.17 V versus SCE (Saturated Calomel Electrode). Moreover, the measured current transient curves were compared to those calculated from Scharifker-Hills and Heerman-Tarallo models. It was found that instantaneous 3D nucleation mechanism governs the nucleation and the growth of Bi on ITO substrate. Using these models we were able to calculate meaningful values for the kinetic parameters of bismuth growth. The characterization of samples was carried out by X-Ray diffraction and UV–Visible spectroscopy. Results showed that all the films were polycrystalline type rhombohedral crystal structure. The preferred orientation of the crystallites is (0 1 2) direction. These films exhibited also a transmittance value of about 40% in the visible range.

Development of multilayer Hydroxyapatite - Ag/TiN-Ti coatings deposited by radio frequency magnetron sputtering with potential application in the biomedical field

The use of composite coatings is emerging as a great alternative to conventional coatings, allowing the combination of different superficial properties that are widely desired in surgical implants, such as osteointegration and bactericidal character, and cannot be provided by one material alone. In the present investigation the effect of the incorporation of a TiN-Ti intermediate bilayer on the chemical composition, structure, morphology, roughness, residual stresses and adhesion of a multi-layer Hydroxyapatite (HA)-Ag coating deposited on Ti-6Al-4V by magnetron sputtering was evaluated. Additionally, the cytotoxicity of the developed system was evaluated by in vitro tests. According to the results obtained, a decrease in the Ca/P ratio from 1.85 to 1.74 was obtained through the deposition of an HA-Ag system on the intermediate bilayer, and the crystallinity of the developed coating was favored. The multi-layer structure was effectively observed by field emission scanning electron microscopy, where it was possible to identify each of the HA, Ag, TiN and Ti layers. Meanwhile, an increase of 7% in crystallite size, a decrease of 36% in residual stresses and an increase of 32% in adhesion were registered for this composite coating compared to the free intermediate bilayer system. Finally, biological evaluation allowed the non-cytotoxic character of the deposited coatings to be confirmed.

Brewster Mode‐Enhanced Sensing with Hyperbolic Metamaterial

AbstractHyperbolic metamaterials (HMMs) are used to demonstrate extreme sensitivity biosensing by exciting their high‐k modes. However, momentum couplers, such as subwavelength diffraction grating or bulky high‐index prism, are required to excite these nonradiative modes, which is not cost‐effective and thus not suitable for point‐of‐care applications. Here, a cost‐effective and scalable HMM‐based sensor platform is proposed and experimentally demonstrated, by exciting the Brewster mode of HMM from free‐space. The excitation of Brewster modes is shown in a multilayered HMM comprising of alternating thin layers of TiN and phase change material, such as Sb2S3. Brewster modes in the hyperbolic region occur due to abrupt phase change, and enhanced Goos–Hänchen shift is realized at the Brewster angle. The enhanced refractive index sensing is demonstrated by exploiting the singular phase of light associated with the Brewster mode of the proposed HMM. This microfluidics integrated lithography‐free nanophotonic device can be a potential sensor platform for a cost‐effective development of label‐free biosensors for point‐of‐care applications.

Microstructural and mechanical study of an induction nitrided Ti gr.5 hip prosthesis component

Ti alloys suffer from intensive wear. To improve these properties, a surface treatment is required (coatings, surface thermal treatment, etc.). One of the major concerns regarding these treatments is that the treatment temperature needs to be controlled in order to avoid microstructural modifications.In this work, an attempt to modify a thin alloy surface layer alone has been performed by means of induction nitriding. By saturating the heating chamber with N, it is possible to produce controlled thickness nitride layers. Current (650–750 A) and cycle number (2–4 with a duration of 8 s each) were varied, and the top view and cross sections of the produced samples were characterized by means of stylus profilometery, SEM (Scanning Electron Microscopy) and visible light microscopy. The produced samples were then studied by microhardness and tensile testing to determine their mechanical properties. Fretting tests were also performed in order to evaluate the wearing behaviour of the surface layers in a corrosive media.The results showed that Ti alloys can be induction nitrided. The process parameters have a strong influence on the formation of TiN and alpha case layers. These layers can affect the mechanical properties and fretting resistance of the samples.

Study on the Use of Ground-Penetrating Radar Technique to Recognize Tin deposits in Bangka Island

Bangka Island, which is situated in the east of Sumatra, is included in the Indonesian tin belt, spanning from the Malayan Peninsula to the southeast direction until Bangka Island. After ten years of exploitation, intensive exploration to locate new tin deposits is needed to add new tin reserve from available resources. This research is aimed at applying Ground-Penetrating Radar (GPR) technique to recognize tin deposits at some location onshore. GPR method is selected among other geophysical methods due to its potential to image subsurface effectively, both in time and campaign cost. GPR Mala RAMAC system equipped with 100 MHz antenna came to use. Three blocks of 200m x 200m area comprising of around 9 in-line and 9 cross-line profiles were investigated. The acquired data were then processed using careful processing steps, including dewow, Butterworth bandpass as well as f-k filtering to avoid information loss. The processed data were then analyzed by using nine characteristic frequencies which are determined in frequency as well as in time domain. With the aid of borehole log data from all of measurements locations, we recognize specific signature associated with Tin layers at depths of 5 - 10 meters.

TiN and Boride Layers Obtained by Dehydrated Paste-Pack Boriding and PVD Treatments Formed on AISI M2 Steel

TiN and Boride Layers Obtained by Dehydrated Paste-Pack Boriding and PVD Treatments Formed on AISI M2 Steel

Interface evaluation on the brazed system of AlN‐Ticusil‐Graphite

AbstractThe graphite‐Ticusil‐AlN system was joined under vacuum or flowing atmospheres, such as 5% H2‐95% N2 and argon atmosphere, to investigate the morphology and forming mechanism of the reaction phases at the interfaces of AlN‐Ticusil‐graphite layers. Scanning electron microscopy, energy‐dispersive spectroscopy, electron probe microanalysis, and transmission electron microscopy were used to examine the composition and structure of the interface products. The AlN‐Ticusil interface could be divided into two layers, the TiN layer and titanium‐copper–rich compound layer. The thickness of the TiN layer was only affected by the joining temperature and could be regarded as mainly dependent on the reaction. The titanium‐copper compound layer was composed of (Ti,Cu,Al)6N column when joined under vacuum and was composed of TiN particles when joined in a flowing atmosphere. The products on the graphite‐Ticusil interface were also examined as TiC, which was strictly bonded with graphite and Ticusil filler.

Metal/Semiconductor Barrier Properties of Non-Recessed Ti/Al/Ti and Ta/Al/Ta Ohmic Contacts on AlGaN/GaN Heterostructures

This paper compares the metal/semiconductor barrier height properties of non-recessed Ti/Al/Ti and Ta/Al/Ta contacts on AlGaN/GaN heterostructures. Both contacts exhibited a rectifying behavior after deposition and after annealing at temperatures up to 550 °C. The ohmic behavior was reached after annealing at 600 °C. High-resolution morphological and electrical mapping by conductive atomic force microscopy showed a flat surface for both contacts, with the presence of isolated hillocks, which had no significant impact on the contact resistance. Structural analyses indicated the formation of the Al3Ti and Al3Ta phases upon annealing. Furthermore, a thin interfacial TiN layer was observed in the Ti/Al/Ti samples, which is likely responsible for a lower barrier and a better specific contact resistance (c = 1.6 10−4 Ωcm2) with respect to the Ta/Al/Ta samples (c = 4.0 10−4 Ωcm2). The temperature dependence of the specific contact resistance was described by a thermionic field emission mechanism, determining barrier height values in the range of 0.58–0.63 eV. These results were discussed in terms of the different microstructures of the interfaces in the two systems.

Mechanical properties and epitaxial growth of TiN/AlN superlattices

TiN/AlN superlattice coatings combine the superlattice effect and the outstanding properties of AlN in its non-equilibrium face-centred cubic (NaCl-type, rs) structure. In comparison with their non-layered counterparts, the superlattice films exhibit superior and strongly bilayer-period-dependent mechanical properties. Here we analyse the structure and mechanical properties of superlattices with AlN layer thicknesses of 0.9, 1.2, and 1.5 nm and different TiN layer thicknesses. We found that the maximum AlN layer thickness, up to which AlN can be fully stabilized in its metastable rs structure, depends on the substrate material and is at least 1.5 nm for coatings on MgO (100) and 0.9 nm for the coatings grown on Si (100) or Al2O311¯02. Our data also show that with increasing thickness of the template layer, the crystallization of AlN in the stable wurtzite structure is favoured. TiN/AlN superlattice coatings on MgO (100) exhibit the highest hardness values, peaking at 37.0 ± 0.5 GPa for AlN layer thicknesses of 0.9 nm and a bilayer period of 2.5 nm. Films with ultra-small bilayer periods exhibit high hardness combined with low values of elastic modulus suggesting a high elastic-strain-to-failure for these coatings. The highest toughness was found for superlattice films grown on MgO (100), scaling inversely with the bilayer period.

Investigations of &lt;i&gt;In Vitro&lt;/i&gt; Corrosion, and Wear Properties of TiN PVD Coating on Ti6Al4V Alloy for Dental Application

Ti alloys have been widely used for biomedical applications.The generated wear debris due to its low wear resistance lead to inflammations and reduce the lifetime of the implant. So, the coating has been used to improve corrosion and wear resistance. In the present work, we report the assessments of TiN coating deposited by CA-PVD on Ti6Al4V alloy for dental applications. The deposited coating was characterized by XRD and SEM. Mechanical properties were assessed using micorindentation. The in vitro corrosion properties was investigated using PDP and EIS in artificial saliva. The wear rate was characterized using the linear reciprocating tribometer. The results showed that a TiN layer with 1.8 µm thickness was deposited with a hardness of 24.9±8.123 GPa and a Modulus of elasticity of 244.7±14.8 GPa. The corrosion study revealed enhancement in the corrosion performance of the coated sample in artificial saliva. The wear rate of the coated samples was also enhanced for the coated sample. The improved surface hardness, corrosion and wear characteristics of the TiN coating suggests that TiN coating would be a potential candidate for dental applications.

The change in the elastic modulus values for the thickness of a multilayer coating based on TiN and CrN layers

The results of investigations the cross section microstructure of a multilayer coating with a thickness of about 6 μm obtained by cathode arc evaporation, are presented. The top layer of the coating is TiN with a thickness of 200 nm, and the base consists of alternating layers of CrN and CrCN with a thickness of 200 nm per layer. Microhardness (H) and elasticity modulus of (E) were measured on the coating surface, on the CrN / CrCN layer surface, and over the cross section of the coating by nanoindentation (NI). It is established that the E values gradient from the surface with E = 313 GPa to the substrate with E = 176 GPa is smooth. The critical load of adhesive strength of the coating determined in the scratch test was 120 N.