Nitride Layer Research Articles

Photo‐Induced Electrical Gating with the Inserting of an Interfacial Carrier Blocking Layer for Organic/Graphene Phototransistors

AbstractAlthough ultrahigh photoconductive gain is achieved in organic semiconductor‐sensitized graphene phototransistors, the response speed is limited by the photo‐induced carrier injection at the organic/graphene interface. In this work, an insulating hexagonal boron nitride layer is inserted between the organic heterostructure and graphene to block the interfacial carrier transport. Above the h‐BN layer, the organic heterostructure is adopted as the light‐absorbing layer, and the photoresponse of graphene is realized through electrical gating of the atop h‐BN dielectric layer, by the accumulated carriers in the organic heterostructure. Under this “photo‐induced electrical gating” mechanism, the recombination of nonequilibrium carriers takes place only within the organic heterostructure. Furthermore, monolayer perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) is deposited on graphene before transfer of the h‐BN, by which the interfacial encapsulated bubbles are effectively reduced. As a step further, the trap states are pre‐filled with background light illumination, then the carrier recombination follows the band‐to‐band pathway. Finally, the response time of the organic/h‐BN/graphene phototransistor is reduced to 7.15 ms, and a high photoresponsivity is achieved even though the carrier multiplication is sacrificed, which is reconciled by the improvement of the device quantum efficiency.

Scratch Response of Hollow Cathode Radiofrequency Plasma-Nitrided and Sintered 316L Austenitic Stainless Steel

Low-temperature plasma nitriding is a thermochemical surface treatment that promotes surface hardening and wear resistance enhancement without compromising the corrosion resistance of sintered austenitic stainless steels. Hollow cathode radiofrequency (RF) plasma nitriding was conducted to evaluate the influence of the working pressure and nitriding time on the microstructure and thickness of the nitrided layers. A group of samples of sintered 316L austenitic stainless steel were plasma-nitrided at 400 °C for 4 h, varying the working pressure from 160 to 25 Pa, and the other group was treated at the same temperature, varying the nitriding time (2 h and 4 h) while keeping the pressure at 25 Pa. A higher pressure resulted in a thinner, non-homogeneous nitrided layer with an edge effect. Regardless of the nitriding duration, the lowest pressure (25 Pa) promoted the formation of a homogenously nitrided layer composed of nitrogen-expanded austenite that was free of iron or chromium nitride and harder and more scratching-wear-resistant than the soft steel substrate.

Investigation on the optimal ultra-precision machining of nitriding mold steel by in-situ laser assisted diamond cutting

S136 (STAVAX ESR) mold steel is an advanced material for the optical mold industry. The precisely machined surface quality is essential for guaranteeing the excellent performance of molds. Diamond cutting is a high-efficiency machining technique in optical mold manufacturing. However, the chemical wear of diamond tool is a huge challenge in precisely machining steel mold due to the reaction between atoms C and Fe. In this study, the hybrid machining technique which combined the in-situ laser assisted diamond cutting (LADC) and plasma nitriding was used to machine S136 mold steel. Furthermore, the impact of the various machining conditions on the machined workpiece surface roughness Sa was comprehensively investigated by the Taguchi method (TM) and Response surface methodology (RSM). The experimental results of material characterization indicated that a 90 μm nitride layer was generated on the workpiece surface by plasma nitriding. Analysis of variance (ANOVA) results demonstrated that the feed rate and laser power had an important impact on the machined surface roughness Sa. According to the RSM, a precise mathematical model was developed which is explored by experimental investigations. The results showed that the optimal machining parameter combination by RSM generated the better surface quality of 6.393 nm in in-situ LADC of nitriding steel. This study provides a reference for mold steel ultra-precision machining technique and parameter optimization method for surface integrity.

Design and study of a new QPQ combined with ultrasonic roller pressing method for gear surface strengthening

This study investigates a hybrid surface enhancement technique that combines Quench Polish Quench (QPQ) with ultrasonic rolling to augment the durability of 42CrMo gears against wear and fatigue. Analysis reveals that post-treatment, the composite nitride layer on the gear surface maintains its original phase composition, evidenced by the absence of new diffraction peaks in X-ray diffraction (XRD) patterns. Nevertheless, a noticeable broadening in these peaks suggests grain refinement and the presence of microstrain due to the rolling process. Incremental static pressures improve the mechanical characteristics of the surface, with the layer treated at 0.6 MPa exhibiting the lowest wear rate (3.15 × 10−8 mm3N−1 m−1). Oxidative wear increases at elevated temperatures (100 °C), yet under lubricated conditions, Coefficient Of Friction (COF) of the treated layer significantly reduces. The predominant wear mechanisms include mild abrasive wear, oxidative wear, and adhesion. Excessive impact force, particularly at 0.6 MPa, risks surface cracking and subsequent degradation in fatigue resistance. Optimal fatigue performance is achieved with a static pressure of 0.4 MPa, corresponding to a surface strength of 2300 MPa and a fatigue life of 3.23 × 106 cycles.

Structural and Optical Properties of Aluminium Nitride Thin Films Fabricated Using Pulsed Laser Deposition and DC Magnetron Sputtering on Various Substrates

Abstract Aluminium nitride thin films were fabricated using pulsed laser deposition and DC magnetron sputtering. Different technological parameters and the effects of different substrates on the optical and structural parameters of AlN samples were studied. An X-ray diffraction study was performed for the layer deposited on the Si3N4 substrate. A high-energy electron diffraction study was also carried out for the layer deposited on a KCl substrate. Transmission spectra of layers on quartz, sapphire, and glass substrates were obtained. An evaluation of the optical band gap of the obtained layers was carried out (Eg form 3.81 to 5.81 eV) and the refractive index was calculated (2.58). The relative density of the film (N1TN-AlN sample) is 1.26 and was calculated using the Lorentz-Lorentz relationship. Layers of aluminium nitride show an amorphous character with a polycrystalline region. It was shown that the properties of AlN films strongly depend on the method, growth conditions, and substrate used.

АНАЛИЗ ВЛИЯНИЯ ПРЕДВАРИТЕЛЬНОЙ И ЦИКЛИЧЕСКОЙ ПЛАСТИЧЕСКОЙ ДЕФОРМАЦИИ НА ХИМИКО-ТЕРМИЧЕСКУЮ ОБРАБОТКУ КОНСТРУКЦИОННЫХ СТАЛЕЙ

The subject of the study was thermodiffusion nitrided and silicified layers on steels obtained after plastic deformation. The influence of preliminary plastic deformation on the low-temperature nitriding process and cyclic plastic deformation on the high-temperature silicification process is studied. The results obtained are of interest for accelerating the production processes of chemical-thermal treatment of steels. It is established that preliminary surface plastic deformation contributes to the intensification of the process of ion-plasma nitriding of structural steel. The presence of high-temperature cyclic plastic deformation ensures the intensification of diffusion processes during the resorption of the diffusion silicified layer on structural steel.

A Review of Nanostructures in Electrowetting-on-dielectric Systems: From Nanostructured Dielectric Layers to Nanofluids

Abstract: The extensive interest in electrowetting-on-dielectric (EWOD) as a key in advancing the efficiency and controllability of fluid-based microelectromechanical and actuator systems has resulted in a deluge of technological research, especially in the area of microfluidics, liquid lenses, and fluid-based lab-on-chips. More recently, the integration of nanostructures into EWOD-driven devices has shown promising improvement in these devices’ performance, design, and miniaturization. Due to the exceptional properties, availability, versatility, and tunability of nanostructures, they are being utilized as components of EWOD systems for various applications. Utilization ranges from fabricating nanodimensional dielectric layers to incorporating nanoparticles in fluid droplets. With the current trend in improving the performance and functionality of EWOD-driven devices at low voltage operations, it is timely to revisit the fundamental principle of EWOD phenomena and how it is extended experimentally using nanostructures. In this paper, we present the different nanostructures investigated as dielectric materials in various EWOD experiments focusing on metal oxide and silicon nitride layers. Notes on the structure of these dielectric layers are also presented. Furthermore, various EWOD experiments employing nanofluid droplets are also described. This paper provides a clear picture of nanostructures’ diverse impact on the advancement of EWOD technology. The insights presented in this paper may also serve as a guidepost for future exploration and development of the role of nanostructures in EWOD-driven devices.

The Effect of La on the Surface Properties of Plasma Nitrided CoCrCuFeNi High-Entropy Alloys at 440 Degrees Celsius

This paper investigates the effect of the element La on plasma nitriding of the CoCrCuFeNi high-entropy alloy (HEA) at 440 °C for 8, 16, and 24 h. The phase composition, morphology, and hardness distribution of the nitrided layer are characterized using XRD, optical microscopy, and a microhardness tester. Furthermore, the corrosion resistance is tested using an electrochemical workstation. The study evaluated the friction and wear performance using a testing machine and scanning electron microscope. The thickness of the effective hardening layer after 16 h of treatment with La was similar to that after 24 h of treatment without La. The addition of La significantly increased the growth rate constant of the effective hardening layer from 0.53 × 10−14 m2/s to 0.72 × 10−14 m2/s. In addition, an expanded FCC phase with greater interplanar spacing can be formed on the surface of the sample by introducing La into the plasma nitriding process. This indicates that the expanded FCC phase, with a higher concentration of interstitial nitrogen atoms, can effectively improve the corrosion resistance of the specimen surface. The corrosion rate of the specimen surface was reduced by 27.5% and the wear rate was reduced by 41.7% after 16 h of treatment with the addition of La compared to 24 h of nitriding without the addition of La. It has been shown that the addition of La to the plasma nitriding process results in a higher quality nitrided layer in a shorter time and also demonstrates that La has the potential to optimize the surface properties of plasma nitrided HEAs.

Revealing the mechanism of interfacial adhesion enhancement between the SiO2 film and the GaAs substrate via plasma pre-treatments

The formation mechanism of a highly adherent silicon dioxide (SiO2) film on gallium arsenide (GaAs) substrate by plasma enhanced chemical vapor deposition (PECVD) is proposed. Ar, N2, and NH3 were used as pre-treatment gas to improve the interfacial adhesion. The interfacial adhesion was measured by the cross-cut tape test. By the measurement of spectroscopic ellipsometry and x-ray photoelectron spectroscopy (XPS), it is revealed that nitrogen plasma pre-treatment had formed a very thin GaN transition layer on the surface, which was responsible for the improvement of interfacial adhesion. XPS depth-profiling further confirmed various pre-treatment gases generate plasma mixtures and form thin film layers with different compositions on the GaAs surface. These layers have a significant impact on the adhesion of the subsequently prepared SiO2 film. The primary mechanism for improving interfacial adhesion is the renovation of the substrate composition via plasma pre-treatment by PECVD, which forms a transition layer of nitrides that eliminates the negative effects of oxides on adhesion. This study reveals the mechanism of interfacial adhesion enhancement between SiO2 film and GaAs substrate, which is of significant importance in fabricating high-performance and reliable semiconductor devices.

Novel high-efficiency plasma nitriding process utilizing a high power impulse magnetron sputtering discharge

Lifetime and biocompatibility of orthopedic implants are crucial in meeting the new challenges brought about by the fall in the patient age and the aging population. The high-load surfaces in contact with the biological environment must display enhanced tribological properties, biocompatibility, and reduced metal ion release in long-term clinical performance. Surface modification techniques such as nitriding can significantly improve the in-service behavior of the medical-grade alloys in current use. We report on a novel approach for nitriding of CoCrMo alloys using high power impulse magnetron sputtering (HIPIMS) discharge. The new nitriding process has been successfully carried out at the National HIPIMS Technology Centre at Sheffield Hallam University, UK, in an industrial size Hauzer 1000-4 system enabled with HIPIMS technology. While the nitriding ion flux is controlled by the HIPIMS magnetron plasma source, the ion energy can be independently set via the substrate bias. Implementing the HIPIMS source allows reducing the operational pressure by one order of magnitude compared to conventional dc plasma nitriding (DCPN). Plasma analyses have identified significantly enhanced production of ions of molecular nitrogen (N2+), atomic nitrogen (N+), and N2H+ radicals in the HIPIMS discharge compared to DCPN. Because of the low pressure of operation of the HIPIMS process, the energy of ions is similar to the bias voltage, whereas the high pressures used in DCPN cause severe losses in ion energy due to scattering collisions within the sheath. The high flux and high ion energy are primarily responsible for achieving a fourfold increase in process productivity as compared to state-of-the-art plasma nitriding processes. The nitrided surface layers exhibit excellent mechanical and tribological properties, which bring about significant improvements in hardness, fracture toughness, and wear. The protective function of the nitrided layer against corrosion in the aggressive environments of simulated body fluid is remarkably augmented. The barrier properties of the nitrided layer have been demonstrated through a reduction in metal ion release by as much as a factor of 2, 4, and 10 for Co, Cr, and Mo, respectively.

Investigation of formation of γN phase layer and its effect on surface properties of 316 L stainless steel bipolar plate for proton exchange membrane fuel cell

In this paper, the surface microstructure and properties of plasma-nitrided 316 L stainless steel bipolar plate with a thickness of 0.1 mm were investigated. The surface microstructure of the nitrided sample was characterized by SEM, TEM, XRD and XPS. After plasma nitriding, a nitrogen-expand austenite (γN phase) layer was formed on the plasma-nitrided sample surface. In γN phase layer, a large amount of stacking fault was formed and the superlattice lattice was found owing to serious lattice distortion under high plasma nitriding condition. The hydrophobic property, conductivity and corrosion resistance of the nitrided samples were obviously improved compared with the untreated sample. Under long time or high temperature condition, although a thicker γN phase layer was formed, the surface corrosion resistance of the plasma-nitrided samples became worse. Under high hydrogen condition, the plasma-nitrided sample surface exhibited the good corrosion resistance and electrical conductivity. The interfacial contact resistance of the sample was only 8 mΩ (≤20 mΩ), and the corrosion resistance of the sample was 90 times higher than that of the untreated sample. The influence of phase composition and microstructure in nitriding layer as well as surface morphology on surface properties of plasma-nitrided sample were analyzed in detail. This work proves that plasma nitriding technology has great advantages in improving surface properties of the bipolar plate.

Reducing Time and Costs of FT-IR Studies of the Effect of SiNx, Dopants, and Emitter on Hydrogen Species in Si Wafers and Solar Cell Structures

Accurately measuring the hydrogen content in silicon (Si) solar cells is essential due to its connection to surface degradation and light and elevated temperature induced degradation (LeTID). Fourier Transform-Infrared (FT-IR) spectroscopy provides a quantitative technique for determining the content of various hydrogen species in Si wafers that have undergone various process steps. In this study, we examine both the effect of a silicon nitride (SiNx:H) layer during FT-IR spectroscopic measurements on hydrogen species, as well as the impact of an emitter present during firing on the amount of hydrogen introduced into Si wafers. We find that the presence of SiNx:H during measurements has negligible effects on the measured hydrogen species, potentially simplifying the preparation steps for FT-IR. For the emitter investigation we analyze boron (B)- and gallium (Ga)-doped p-type wafers to detect H-B, H-Ga, Oi-H2, and H2. We observe that hydrogen species initially present in B- and Ga-doped Si wafers differ significantly. Only H-Ga is detected in Ga-doped wafers, while H-B, Oi-H2, and H2 signals are measured in B-doped wafers. Moreover, we cannot confirm an increased release of H through the emitter into the bulk during the firing process. Finally, we conduct measurements at different temperatures and confirm that cryogenic temperatures are more effective for detecting H-B and H2 with concentrations in the 1014 cm-3 range. Nevertheless, useful spectra can still be obtained at liquid nitrogen (N2) temperatures.

Tailoring optical response in nanostructured bilayers: Effects of surface roughness and layer thickness on NbN/Nb and TiN/Ti

Numerical calculations were performed on NbN/Nb and TiN/Ti nanostructured bilayers. Discrete dipole approximationimplemented in the DDSCAT code was utilized. In order to design a TUC (Target Unit Cell) with realistic surfaceroughnesspattern, Atomic Force Microscope images of 100 ±10 nm Nb thin films were used. The optical properties of nanostructured bilayers (60-100 nm thickness with a ±10 nm surface roughness) were calculated, keeping the interfacebetween the layers as smooth flat surfaces. For the NbN/Nb nanostructure with a thickness between 100 ±10 nm, and 70 ±10 nm, in a wavelength range between 200 and 350 nm, the reflectance and absorptance show a nearly flat spectrumwith an intensity of 20% and 80%, respectively. For larger wavelengths, absorptance decays smoothly. In contrast, for the 60 ±10 nm bilayer, the absorptance decays faster. For the TiN/Ti nanostructure, at 415 nm, a relative maximum in the reflectance, and a minimum in absorptance, are observed. The critical value of the absorbed light spectra begins to shift to higher wavelengths as the thickness of the TiN layer increases. We demonstrate that adding a rough nitride layer on top of its metallized layer drastically modifies the optical response of the nanostructured bilayer, an interesting result forplasmonics and nanoelectronics applications.

Argon ion sputtering bridging plasma nitriding and GLC film deposition: Effects on the mechanical and tribological properties

A duplex coating consisting of a nitrided layer and a GLC (Graphite-like carbon) film was deposited on the surface of the M50NiL steel via a one-step process in a plasma nitriding system. The influence of argon ion sputtering, a critical process bridging plasma nitriding and GLC film deposition, was studied. Effects of argon ion sputtering on the growth of the GLC film were investigated by means of Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The mechanical and tribological properties of the duplex coating were evaluated by a Vickers hardness tester, a scratching tester and a rotating ball-on-disc tribometer. Results reveal that pre-treatment by ion sputtering improves the surface condition of the nitrided layers and increases its surface energy, thus facilitating nucleation growth and GLC film adhesion. The combined effect of better film-substrate adhesion, strong interfacial chemical interaction and the self-lubricating features of the GLC films are the main reasons for the excellent tribological properties of the coating. This study may provide a new idea for optimizing the duplex coating (nitrided layer + GLC film) with excellent tribological properties and high durability.

ADJUSTABLE NITROOXIDATION TECHNOLOGY FOR LOW ALLOY STEEL

The article discusses the production of a surface diffusion nitride-oxide layer on low-alloy structural steel with specified structures and properties. To develop a controlled technology for nitro-oxidation of low-alloy carbon steel, the dependences of the composition and structure of the nitrided and oxide layer on the chemical composition of the steel and the technological parameters of the process were studied. Technical iron was used as a model alloy and samples of industrial steel grades 40X, P6M5 and steel 45 were processed. Saturation temperatures were studied in the ranges above and below the eutectoid temperature for the “Fe-N” system and, accordingly, for the “Fe-O” system and it was found that the best structures are at saturation temperatures below the eutectoid.

Mitigating WL-to-WL Disturbance in Dynamic Random-Access Memory (DRAM) through Adopted Spherical Shallow Trench Isolation with Silicon Nitride Layer in the Buried Channel Array Transistor (BCAT)

The Pass Gate Effect (PGE), often referred to as adjacent cell interference, presents a significant challenge in dynamic random-access memory (DRAM). In this study, we investigate the impact of PGE and propose innovative solutions to address this issue in DRAM technology, employing 10 nm node technology with buried channel array transistors. To evaluate the efficacy of our proposals, we utilized SILVACO for simulating various DRAM configurations. Our approach centers on two key structural optimizations: the introduction of a spherical Shallow Trench Isolation (STI) and the incorporation of a silicon nitride (Si3N4) layer within the spherical STI structure. These optimizations were meticulously designed to mitigate the PGE by considering several factors that are highly influential in its manifestation. To validate our approach, we conducted comprehensive simulations, comparing the PGE factors of typical DRAM structures with those of our proposed configurations. The results of our analysis strongly support the effectiveness of our proposed structural enhancements in alleviating the PGE when contrasted with conventional DRAM structures. Remarkably, our optimizations achieved a remarkable 82.4% reduction in the PGE, marking a significant breakthrough in the field of DRAM technology. By addressing the PGE challenge and substantially reducing its impact, our research contributes to the advancement of DRAM technology, offering practical solutions to enhance data integrity and reliability in the era of 10 nm node DRAM.

Series-Biased Micro-LED Array for Lighting, Detection, and Optical Communication

Micro-LED arrays exhibit high brightness, a long lifespan, low power consumption, and a fast response speed. In this paper, we have proposed a series-biased micro-LED array by using a nitride layer with multi-quantum wells epitaxial on sapphire substrate. The III-nitride multiple quantum wells serving as the micro-LED active material enable both luminescence and detection functionalities. The micro-LED array combines lighting, detection, and communication capabilities. We have conducted a thorough analysis of the micro-LED array’s optoelectronic features in both lighting and detection modes. We also explore visible light communication performance across different arrangements of single micro-LED devices within the series-biased array. Our research achieves 720p video transmission via visible light communication using the micro-LED array, supporting a communication rate of up to 10 Mbps. Our contributions encompass the successful integration of lighting and detection functions and a comprehensive assessment of optoelectronic and communication performance. This study highlights the multifunctional micro-LED array’s potential as a transceiver terminal in visible light communication systems, expanding its applications from smart lighting to visible light communication and photonic integrated chips. These innovations enhance our understanding of micro-LED technology and its versatile applications.

The influence of heat treatment on the nitriding layer on austenitic steel

The article will be focused on the analysis of the influence of heat treatment on the nitriding layer, which will be applied on austenitic steel. AISI 304 austenitic steel delivered without heat treatment will be used as experimental material. The nitriding layer will be applied to the austenitic steel samples by plasma nitriding. Then, after plasma nitriding, samples will be subjected to heat treatment. Solution annealing and sensitization will be chosen as heat treatment. Experiments deal with microstructural material analysis, fractographic analysis, mechanical and fatigue tests.

Layered carbon nitride films deposited under an oxygen-containing atmosphere and their electronic properties

Layered carbon nitride (g-C3N4) is a novel semiconducting and functional material for optoelectronic applications. The physical and chemical properties of g-C3N4 films differ depending on the preparation atmosphere. Herein, we deposited g-C3N4 films under a mixed oxygen (O2)-nitrogen (N2) gas atmosphere and studied their effects on the carrier transport properties. Although no significant change in the film orientation was observed, the deposition rate decreased as the O2 gas ratio in the mixed N2/O2 atmosphere increased. Despite their thinness, the luminescence intensity of g-C3N4 films deposited under an O2-containing atmosphere increased by 3.5–5.0 times compared to that deposited under an N2 atmosphere. With respect to voltage application, carrier transport owing to the thermionic emission and/or direct tunneling initially followed ohmic conduction, followed by insufficient trap-filled conduction. As the applied voltage increased further, fully trap-filled conduction was confirmed owing to Fowler–Nordheim tunneling. Moreover, the conductivity type could be changed to p-type and n-type using N2 gas and mixed N2/O2 gas atmospheres, respectively, during film deposition. In addition to the intrinsic transport properties, the intentionally formed Schottky barrier also affected the carrier transport; therefore, the diode-like rectifying behavior of the current density was achieved.

ПОЛУЧЕНИЕ НАНОСТРУКТУРИРОВАННЫХ БИОЛОГИЧЕСКИ АКТИВНЫХ ПОКРЫТИЙ НА ОСНОВЕ НИТРИДА ГАФНИЯ ДЛЯ МЕДИЦИНСКИХ ИМПЛАНТАТОВ И МЕДИЦИНСКИХ ИНСТРУМЕНТОВ ЗА СЧЕТ АКТИВАЦИИ ПОВЕРХНОСТИ ПОТОКОМ НИЗКОЭНЕРГЕТИЧЕСКИХ ИОНОВ

The possibility of obtaining biologically active materials with antimicrobial properties has been studied. The materials are made on the basis of multilayer nanostructured coatings, which were obtained by condensation with ion bombardment of nitride layers on medical instruments in a nitrogen atmosphere. The surface was treated in a flow of low-energy ions with energies ranging from 70 to 100 eV. We received a medical instrument with a high-strength coating that has an antimicrobial effect. IT has no negative effect on animal cells, with a proliferation index of 1.07-2.0. The research results suggest that the method for producing ion-plasma coatings based on hafnium nitrides with their subsequent activation is promising for the technology of manufacturing surgical metal implants and medical instruments.