TiN Diffusion Research Articles

Effect of TiN coating on suppressing Ce-Fe interaction under irradiation

Advanced cladding is critical for fast reactors with the adequate thermal conductivity, mechanical stability and radiation tolerance of the cladding base material, corrosion resistance and high temperature coolant compatibility of the cladding surface, and chemical stability of the cladding inner wall against fuel cladding chemical interaction (FCCI). The preliminary results of recent ion irradiation studies of two diffusion-couple samples of cerium (Ce)/oxide-dispersion strengthened steel (ODS) and Ce/TiN/ODS, irradiated with 80 MeV xenon (Xe) ions to 100 displacements per atom (dpa) at 500°C, are summarized. Significant Ce-Fe interaction occurred in the Ce/ODS sample, and no noticeable Ce-Fe interaction was found in the Ce/TiN/ODS sample. It shows the effectiveness of 1-µm TiN diffusion barrier coated by the pulsed laser deposition on suppressing Ce-Fe interaction, a major contributor to FCCI in cladding. Density function theory (DFT) calculations of the impurity diffusivities of Ce and Fe within the Ti sublattice of TiN were performed to assist a mechanistic understanding of the experimental results.

(Invited) Efficient P-Doping Via Suppressing Bad P−Sn Interaction

The utilization of non-metallic phosphorus (P) doping is recognized for its advantages in enhancing the conductivity of hematite while minimizing recombination. This is attributed to the suppression of electron trapping facilitated by the favorable electron state of P5+. However, our investigation reveals a significant impact on the overall photoelectrochemical (PEC) performance of P-doped Fe2O3 due to tin (Sn) diffusion from the bottom FTO substrate. Upon identifying the unfavorable interaction between the unintentional dopant Sn4+ and intentional dopant P5+, we have developed a straightforward P-doping method. The resulting P:Sn:Ti-Fe2O3 (P:Sn:Ti triple-doped Fe2O3) exhibits a remarkable improvement in photocurrent density, reaching 3.44 mA cm−2 at 1.23 VRHE, surpassing values reported in previous P-doping hematite studies. Following co-catalyst deposition, the NiFeOx/P:Sn:Ti-Fe2O3 photoanode achieves a maximum photocurrent density of 4.30 mA cm−2 at 1.23 VRHE. This study affirms that suppressing the negative interaction between dopants is crucial for significantly enhancing PEC performance.

Volcanic Eruption in the Nanoworld: Efficient Oxygen Exchange at the Si/SnO2 Interface.

Here, a phenomenon of efficient oxygen exchange between a silicon surface and a thin layer of tin dioxide during chemical vapor deposition is presented, which leads to a unique Sn:SiO2 layer. Under thermodynamic conditions in the temperature range of 725-735°C, the formation of nanostructures with volcano-like shapes in "active" and "dormant" states are observed. Extensive characterization techniques, such as electron microscopy, X-ray diffraction, synchrotron radiation-based X-ray photoelectron, and X-ray absorption near-edge structure spectroscopy, are applied to study the formation. The mechanism is related to the oxygen retraction between tin(IV) oxide and silicon surface, leading to the thermodynamically unstable tin(II)oxide, which is immediately disproportionate to metallic Sn and SnO2 localized in the SiO2 matrix. The diffusion of metallic tin in the amorphous silicon oxide matrix leads to larger agglomerates of nanoparticles, which is similar to the formation of a magma chamber during the natural volcanic processes followed by magma eruption, which here is associated with the formation of depressions on the surface filled with metallic tin particles. This new effect contributes a new approach to the formation of functional composites but also inspires the development of unique Sn:SiO2 nanostructures for diverse application scenarios, such as thermal energy storage.

Fabrication of Tin and Zinc Gas Diffusion Electrodes for Electrochemical Reduction of Carbon Dioxide

This study explores the electrochemical reduction of carbon dioxide (CO2) using tin (Sn) and zinc (Zn) catalyst-loaded gas diffusion electrodes (GDEs). The research explores the influence of electrolytic potential and catalyst loading on the efficiency of CO2 conversion to valuable chemicals, specifically formic acid and carbon monoxide. The best Sn loading for Sn-loaded GDEs, according to the morphological study, is 7 mg.cm-2, which results in higher current density (0.33 mA.cm-2) and current efficiency (36%). An electrolytic potential of -1.3 V Vs. Ag/AgCl is identified as optimal for Sn GDEs, offering a balance between high current efficiency (35%) and controlled current density. For Zn-loaded GDEs, an optimal loading of 5 mg.cm²- yields the highest current efficiency of 19.4% and a peak current density of 0.28 mA.cm²- at an electrolytic potential of -1.55 V Vs. Ag/AgCl, in addition to highlighting the crucial role that catalyst loading and electrolytic potential play in enhancing CO2 reduction efficiency, this research offers insightful information for environmentally friendly CO2 conversion technology.

Influence of the TiN diffusion barrier on the leakage current and ferroelectricity in an Al-doped HfOx ferroelectric memristor and its application to neuromorphic computing.

The HfOx-based ferroelectric memristor is in the spotlight due to its complementary metal-oxide-semiconductor compatibility and scaling compared to existing perovskite-based ferroelectric memory. However, ferroelectric properties vary depending on the coefficient of thermal expansion of the top electrode, which is caused by strain engineering. When tungsten (W) with a small coefficient of thermal expansion is used as an electrode, the ferroelectric properties are improved, although the reliability is poor due to the diffusion of W atoms. Here, TiN can be used to prevent the diffusion of W. This metal nitride successfully suppresses the leakage current and induces a larger remanent polarization of 19.7 μC cm-2, a smaller coercive voltage of 9.26 V, and a faster switching speed. W/TiN/HAO/n+ Si can also exhibit multi-level characteristics and achieve a 10% read margin in 320 × 320 arrays. Ferroelectrics can also be applied to neuromorphic computing by imitating synaptic properties such as potentiation, depression, paired-pulse facilitation, and excitatory postsynaptic current. Using short-term plasticity, successful implementation in reservoir computing is also realized, achieving 95% classification accuracy. This paper shows promise for the use of memristors in artificial neural networks.

Evolution behavior of δ phase in Cu12Sn2Ni alloy and the corresponding effects on alloy property

AbstractWith the increase of tin content in tin bronze, the rise of δ phase made the strength, hardness of tin bronze increase and the ductility decrease sharply, that difficult to process. In this paper, the Cu12Sn2Ni alloy was prepared by centrifugal casting, the microstructure and phase formation before and after heat treatment were observed by x‐ray diffraction, scanning electron microscope, and transmission electron microscope. The results showed that the as‐cast sample microstructure was composed of equiaxed grains rather than coarse dendrites. centrifugal casting inhibits tin diffusion to form metastable phase β′‐Cu13.7Sn. The as‐cast sample had good deformability and its tensile strength and elongation were 381.9 MPa and 12.4 %, respectively, which are higher than the mechanical properties of gravity casting. The tensile strength and elongation of the sample after furnace cooling at 620 °C/8 min are 439.5 MPa and 24.4 %, respectively, the increase was 16.6 % and 85.07 %, compared with the as‐cast samples, due to the solid solution strengthening, the second phase strengthening and the homogenization of the microstructure.

Super-Linear-Threshold-Switching Selector with Multiple Jar-Shaped Cu-Filaments in the Amorphous Ge3 Se7 Resistive Switching Layer in a Cross-Point Synaptic Memristor Array.

The learning and inference efficiencies of an artificial neural network represented by a cross-point synaptic memristor array can be achieved using a selector, with high selectivity (Ion /Ioff ) and sufficient death region, stacked vertically on a synaptic memristor. This can prevent a sneak current in the memristor array. A selector with multiple jar-shaped conductive Cu filaments in the resistive switching layer is precisely fabricated by designing the Cu ion concentration depth profile of the CuGeSe layer as a filament source, TiN diffusion barrier layer, and Ge3 Se7 switching layer. The selector performs super-linear-threshold-switching with a selectivity of > 107 , death region of -0.70-0.65 V, holding time of 300 ns, switching speed of 25 ns, and endurance cycle of >106 . In addition, the mechanism of switching is proven by the formation of conductive Cu filaments between the CuGeSe and Ge3 Se7 layers under a positive bias on the top Pt electrode and an automatic rupture of the filaments after the holding time. Particularly, a spiking deep neural network using the designed one-selector-one-memory cross-point array improves the Modified National Institute of Standards and Technology classification accuracy by ≈3.8% by eliminating the sneak current in the cross-point array during the inference process.

Diffusion behaviors of Sn dopant in ITO films upon supercritical CO2 treatment and annealing

Indium Tin Oxide (ITO) thin films have been extensively studied for their excellent photoelectric performance. Nevertheless, the diffusion mechanism of doped-tin in ITO thin film is not sufficiently illuminated to date. Herein, the diffusion behaviors of Sn dopant in ITO films fabricated by RF-sputtering were investigated. As-deposited ITO thin films were treated by supercritical CO2 (SCCO2) fluid with aqua ammonia, then they were annealed at different temperatures. X-ray diffraction patterns (XRD) showed that the crystallization of ITO films occurred upon annealing above 300 °C, which resulted in the higher mobility of electron carriers. Relatively lower electron carrier concentrations were found for the ITO films after SCCO2 treatment and successive annealing at temperatures of 500 and 600 °C. X-ray photoelectron spectroscopy (XPS) analysis revealed that the content of tin element near the surface of ITO thin films can be reduced by SCCO2 fluid treatment. Subsequently, the annealing process results in the diffusion of the tin element to the sub-surface region of the films at different levels depending on the annealing temperature. The present work provides direct evidence for bleaching of tin dopant in the sub-surface region of ITO films by SCCO2 treatments and diffusion of tin from deeper regions to the sub-surface region of the ITO films upon annealing.

Effect of TiN diffusion barrier layer on residual stress and carrier transport in flexible CZTSSe solar cells

The major drawback of flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is the inevitable residual stress in CZTSSe that considerably limits the efficiency and flexibility of these cells. Hence, in this work, TiN layers with varying thicknesses were sputtered between flexible Ti substrates and back contact Mo layers as diffusion barriers. The TiN barrier layer relieved residual stress, facilitated grain growth, and decreased the porosity of CZTSSe, thereby effectively suppressing the formation of carrier recombination paths and improving the mechanical strength of CZTSSe. Meanwhile, the band alignment of the CZTSSe/CdS heterojunction could be significantly tailored, leading to an improved ‘‘cliff-like’’ conduction band offset from −0.49 eV to −0.33 eV. Under the optimized TiN layer thickness of 50 nm, the power conversion efficiency of the fabricated flexible CZTSSe solar cell increased considerably from 3.43% to 4.85% along with high bending stability. Therefore, introducing the TiN diffusion barrier into traditional flexible CZTSSe solar cells improves the efficiency and flexibility of these devices. Moreover, this method could be a promising pathway for the large-scale production of smart, flexible, and portable electronic devices.

Structure Formation of Diamond-Containing Coatings during Sintering of Specially-Shaped Grinding Wheels

In this work, the structure formation of powder diamond-containing coatings with Sn-Cu-Co binders during sintering of specially-shaped grinding wheels has been studied. The kinetics of structure formation was studied using diamond-free metallic binders and diamond-containing samples. Powder components of the coatings were mixed with an organic plasticizer and applied on steel workpieces by rolling. Sintering was performed in vacuum at 700–820 °C. The microstructure, phase composition, and distribution of elements in metallic binders and interface layers between the binders and steel base were studied. The morphology of the surface and structure of fractures of the diamond-containing samples have been examined. Stages of structure formation of the coatings during heating and sintering have been found. At 700–780 °C, diffusion of tin into copper particles plays the key role in the structure formation of the coatings. Dissolution-reprecipitation of cobalt at 780–820 °C has a significant effect on formation of the coating structure and interface layers between the coating and steel base.

Measurement of Thermal Diffusivity of Thin Film in Thickness Direction Using an Ordinary Dielectric Film as the Sensor

Accurate thermal parameters of thin films are beneficial for the engineering thermal design and thermal management of electronic devices to improve the operating stability and prolong service life. In this article, a novel method for measuring the thermal diffusivity of thin films is proposed based on the thermal pulse method (TPM) for mapping space charge distribution, whose thermal response current is strongly determined by the temperature profiles within thin film. A multi-layer thin film structure is adopted, in which the tested film layer is thermally coupled on the dielectric film substrate with thermal parameters known. The thermal pulse by laser pulse excites the tested film and then penetrates into the dielectric film substrate. By analyzing the thermal response current of the dielectric film substrate, one can deduce the temperature profiles in both layers and therefore the thermal diffusivity of the tested film. The proposed method can determine the thermal diffusivity of both insulating and electric conduction films with the thickness tens of micrometers in through thickness direction. The obtained values of the thermal diffusivity of polyimide (PI), bi-oriented polypropylene (BOPP), polyethylene 2,6-naphthalate (PEN), tin(Sn) foil, and lead (Pb) foil are well consistent with the data provided in the literatures. By the analyzing heat boundary conditions, the interface thermal resistance between the tested film and the dielectric film substrate can be also determined at the same time.

A controlled nucleation and growth of Si nanowires by using a TiN diffusion barrier layer for lithium-ion batteries.

Uniform size of Si nanowires (NWs) is highly desirable to enhance the performance of Si NW-based lithium-ion batteries. To achieve a narrow size distribution of Si NWs, the formation of bulk-like Si structures such as islands and chunks needs to be inhibited during nucleation and growth of Si NWs. We developed a simple approach to control the nucleation of Si NWs via interfacial energy tuning between metal catalysts and substrates by introducing a conductive diffusion barrier. Owing to the high interfacial energy between Au and TiN, agglomeration of Au nanoparticle catalysts was restrained on a TiN layer which induced the formation of small Au nanoparticle catalysts on TiN-coated substrates. The resulting Au catalysts led to the nucleation and growth of Si NWs on the TiN layer with higher number density and direct integration of the Si NWs onto current collectors without the formation of bulk-like Si structures. The lithium-ion battery anodes based on Si NWs grown on TiN-coated current collectors showed improved specific gravimetric capacities (>30%) for various charging rates and enhanced capacity retention up to 500 cycles of charging–discharging.

Comparison of CrN, AlN and TiN Diffusion Barriers on the Interdiffusion and Oxidation Behaviors of Ni+CrAlYSiN Nanocomposite Coatings

CrN, AlN, TiN layer were prepared as diffusion barriers between the K417 substrate and Ni+CrAlYSiN nano composite coatings via vacuum arc evaporation. Oxidation kinetics and microstructure evaluation of these nano coating systems at 1000 °C after 100 h were studied. Results show that the AlN layer showed good thermodynamic stability, effectively inhibited the interdiffusion between the coating and the substrate, improved the oxidation resistance of Ni+CrAlYSiN nano composite coatings, and a single-layer Al2O3 film was formed on the coating. The CrN layer was decomposed, which did not block the diffusion of elements and had little effect on the oxidation resistance of the Ni+CrAlYSiN nano composite coating. The TiN layer effectively prevented the interdiffusion between the coating and the substrate. However, it deteriorated the oxidation resistance of the composite coating. Similar to the Ni+CrAlYSiN coating without a diffusion barrier, a double-layer oxide film structure with Al2O3 as the inner layer and Ni(Al,Cr)2O4 as the outer layer formed on the Ni+CrAlYSiN nano composite coatings with the CrN or TiN diffusion barrier.

NiFeOx decorated Ge-hematite/perovskite for an efficient water splitting system

To boost the photoelectrochemical water oxidation performance of hematite photoanodes, high temperature annealing has been widely applied to enhance crystallinity, to improve the interface between the hematite-substrate interface, and to introduce tin-dopants from the substrate. However, when using additional dopants, the interaction between the unintentional tin and intentional dopant is poorly understood. Here, using germanium, we investigate how tin diffusion affects overall photoelectrochemical performance in germanium:tin co-doped systems. After revealing that germanium is a better dopant than tin, we develop a facile germanium-doping method which suppresses tin diffusion from the fluorine doped tin oxide substrate, significantly improving hematite performance. The NiFeOx@Ge-PH photoanode shows a photocurrent density of 4.6 mA cm−2 at 1.23 VRHE with a low turn-on voltage. After combining with a perovskite solar cell, our tandem system achieves 4.8% solar-to-hydrogen conversion efficiency (3.9 mA cm−2 in NiFeOx@Ge-PH/perovskite solar water splitting system). Our work provides important insights on a promising diagnostic tool for future co-doping system design.

Experimental Investigation of Microstructural Effects in Sn-Pb Solder Accumulated During Ten Years of Service Life

Aim: Solder joints of microelectronic devices are subjected to a wide range of loadings. They affect the microstructural evolution of the alloy. Long term investigations are commonly performed under thermally accelerated conditions, but are not available for real-life environmental conditions in literature yet. Therefore, the solder bumps of ten-year-old graphic cards are inspected here. Objectives: The primary objective of this study was the investigation of long-term accumulated effects in solder bumps. We classified the solder concerning its prior electrical functionality and analyzed theproperties of the microstructure. Methods: The image reconstruction is based on component identification, scratch elimination, and image stitching. Additionally, environmental scanning electron micrographs are employed to investigate the microstructure of the lead-rich phases. Results: Power supplying solder has the widest circularity distribution as a result of anisotropic diffusion and phase decomposition. On average, a bump with a cross-section of 0.12 mm2 contains 800 Pbrich phase islands. In the central region of the solder, broad Pb-rich platelets are present. Such platelets are typically perpendicular to the electric current flow and affected by the mechanical deformation of the bump. Additional electron-microscopy shows several micro-porous Pb-rich phase islands, which are induced by an uncalibrated diffusion of tin. Conclusion: We found the phase islands’ circularity to be the best indicator for the bulk dynamics. We conclude that device operation at normal working conditions leads to no hints for functional limitations at the end of the designed life span.

Cold Roll Bonding of Tin-Coated Steel Sheets with Subsequent Heat Treatment

One possibility to increase the interface strength of cold roll bonded materials is the application of a thin intermediate layer. In the present study, a tin coating was employed to strengthen the interface formed between cold roll bonded steel sheets, and the impact of subsequent heat treatment on the resulting bonding strength was investigated. To increase the bond strength by diffusion, the tin-coated steel bonds underwent heat post-treatment between temperatures of 150 °C and 300 °C for different dwell times. The results demonstrate that the use of tin as an active intermediate layer increases the bond area established. Moreover, the thin tin coating results in the formation of an active intermediate layer that directly takes part in the joining process by establishing a reactive link between the two substrates. A subsequent heat treatment further affects the bond strength by diffusion of tin at the interface.

The Effect of Naphthalene‐Based Additives on the Kinetics of Tin Electrodeposition on Boron‐Doped Diamond Electrodes

AbstractThe effect of naphthalene‐based additives: naphthalene (NPT), naphthalenesulfonate (NPTS) and hydroxynaphthalenesulfonate (HNPTS) on the kinetics of tin electrodeposition on a boron‐doped diamond (BDD) electrode has been studied by means of chronoamperometry and scanning electron microscopy (SEM). Potentiostatic current transients in the absence and the presence of naphthalene‐based additives are analyzed by using the Scharifker‐Hills model. A strong decrease of the kinetics of tin nucleation on BDD was observed in the presence of naphthalene‐based additives, NPT showing the smallest effect and HNPTS showing the largest effect. From the long‐term Cottrell behavior of the transients, similar values of tin(II) diffusion coefficients were obtained for all additives, suggesting that there is no complexation of Sn(II) by the additives and that the charge‐transfer kinetics itself is not substantially influenced by the presence of the additives. In the absence of additives, tin deposition on BDD displays a progressive nucleation and growth mechanism at the least negative potentials, switching to instantaneous nucleation and growth at more negative potential. In the presence of NPTS and HNPTS, progressive nucleation and growth transients are observed. The growth mode results are confirmed by the tin features observed in the scanning electron micrographs. In conclusion, NPT, NPTS and HNPTS mainly decrease the rate of the nucleation of tin deposition, most likely by blocking or reducing access to active nucleation sites. In comparison, ethoxylated α‐napthalenesulfonic acid (ENSA, a commonly used additive in the tin plating industry) inhibits tin deposition process on BDD even more strongly. These observations show a striking similarity to our previous study of tin deposition on gold electrodes.

Annealing effects on interdiffusion in layered FA-rich perovskite solar cells

Annealing is one of the processing methods that are used for the fabrication of defect-free, photoactive perovskite films with compact grains in highly efficient and stable perovskite solar cells (PSCs). Thus, the annealing temperature is a key parameter for the control of the interdiffusion (of constituent elements) in photoactive films. In this paper, we present the results of a systematic study of the effects of annealing on the interdiffusion of constituent elements in efficient formamidinium-based PSCs. We also explore the effects of annealing-induced interdiffusion on layer microstructures, local strains, and the optoelectronic properties of perovskite films. We observe a dramatic upward diffusion of tin (Sn) and titanium (Ti) from fluorine-doped tin oxide and titanium dioxide (TiO2) to the perovskite films. We also observe a downward diffusion of lead (Pb) and iodine (I) from the perovskite films to the mesoporous layer of the electron transporting layer (ETL), after annealing at temperatures between 100 and 150 °C. The diffused I substitutes for Ti in the ETL, which improves the optoelectronic properties of the films, for annealing temperatures between 100 and 130 °C. The annealing-induced interdiffusion that occurs at higher temperatures (between 140 and 150 °C) results in higher levels of interdiffusion, along with increased local strains that lead to the nucleation of pores and cracks. Finally, the implications of the results are discussed for the design of PSCs with improved photoconversion efficiencies and stability.

Fully dense, highly conductive nanocrystalline TiN diffusion barrier on steel via reactive high power impulse magnetron sputtering

We report fully dense and nanocrystalline TiN that is also highly conductive, using reactive HiPIMS (High power impulse magnetron sputtering) at room temperature. These films are useful as a diffusion barrier for metal interconnects and thin-film solar cells on steel. HiPIMS is known to generate a very dense plasma, which improves the physical properties of TiN even for room-temperature deposition. As the peak power increased from 2.6 kW to 16.6 kW, the films became more nanocrystalline and denser, with the best value of 5.47 g/cm3. Despite the loss in structural order, increasing peak power decreased the film resistivity, from 240 µΩcm to 56 µΩcm; and reduced the roughness from 3.8 nm to 1.2 nm. Compared to TiN from DC sputtering, the electrical resistivity of 16.6 kW HiPIMS TiN is 23-times lower. HiPIMS TiN deposited films are thermally stable up to 900°C. The diffusivity of Fe in HiPIMS TiN films at 700 to 900°C was quantified using secondary ion mass spectrometry. Fe diffuses by bulk and grain-boundary diffusion, with the latter dominating for these polycrystalline films. As expected, the denser HiPIMS TiN also has lower bulk diffusivity of 2.6×10−16cm2s−1, comparable to the state-of-art. HIPIMS may be one of the best techniques to deposit TiN barrier films for solar cells on steel.

Plasma-Enhanced Atomic Layer Deposition of TiN Thin Films as an Effective Se Diffusion Barrier for CIGS Solar Cells.

Plasma-enhanced atomic layer deposition (PEALD) of TiN thin films were investigated as an effective Se diffusion barrier layer for Cu (In, Ga) Se2 (CIGS) solar cells. Before the deposition of TiN thin film on CIGS solar cells, a saturated growth rate of 0.67 Å/cycle was confirmed using tetrakis(dimethylamido)titanium (TDMAT) and N2 plasma at 200 °C. Then, a Mo (≈30 nm)/PEALD-TiN (≈5 nm)/Mo (≈600 nm) back contact stack was fabricated to investigate the effects of PEALD-TiN thin films on the Se diffusion. After the selenization process, it was revealed that ≈5 nm-thick TiN thin films can effectively block Se diffusion and that only the top Mo layer prepared on the TiN thin films reacted with Se to form a MoSe2 layer. Without the TiN diffusion barrier layer, however, Se continuously diffused along the grain boundaries of the entire Mo back contact electrode. Finally, the adoption of a TiN diffusion barrier layer improved the photovoltaic efficiency of the CIGS solar cell by approximately 10%.