AIM AND SCOPE Iraqi Journal of Materials (IJM) aims to provide a leading international forum for material researchers across the disciplines of theory, experiment, and device applications. It publishes original studies and reviews related to the calculation, synthesis, processing, characterization, and understanding of advanced quantum materials such as low-dimensional materials, topological materials, meta-materials, correlated electronic materials, and novel magnetic materials, as well as how these materials can be utilized in the construction of novel devices like quantum computers, quantum sensors, spintronics and optoelectronics devices. Studies including demonstrations of these devices are also welcome.
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Effect of ZnO Nanoparticles Weight Content on Lasing Threshold of Fluorescein Dye-Based Random Lasers
In this work, ZnO nanoparticles with different weight contents (0.01, 0.03, 0.05, 0.07, and 0.09 mg) were incorporated in solid solutions of fluorescein laser dye dissolved in epichlorohydrin resin to fabricate random gain media. The effects of ZnO nanoparticles weight content on the pumping threshold and emission intensity were introduced. Lower contents showed higher threshold levels whereas the higher contents has decreased the threshold level due to increasing the scattering centers and hence amplification of random laser signal. This attempt is required to optimize the design parameters of random lasers based on fluorescein/ZnO nanoparticles nanocomposites.
Copyright (c) 2026 IRAQI JOURNAL OF MATERIALS https://creativecommons.org/licenses/by/4.0
Nickel Oxide Nanostructures Synthesized by thermal Oxidation/Limited Fusion Technique
In this study, nickel oxide (NiO) nanostructures were synthesized using a thermal oxidation/limited fusion technique. These nanostructures showed highly crystalline, phase-pure face-centered cubic bunsenite structure, with most of the growth happening along the (200) plane. A dense network of interlocking nanoparticles and polyhedral clusters, all smaller than 100 nm, were revealed, which gives the material a high surface-to-volume ratio. The composition was nearly ideal, with a nickel-to-oxygen ratio of about 1:0.94. The synthesized samples were highly transparent in the visible spectrum and had a wide indirect bandgap of 3.85 eV, just a little blue-shifted from bulk NiO as a result of quantum size effects. These results show that thermal oxidation/limited fusion is a solid method to produce robust NiO nanostructures that are well-suited for things like gas sensors, supercapacitors, and optoelectronic devices.
Effects of Reinforcing Material Content on Physical Properties of C-Al-Si-Ti Coatings Prepared by Flame Spray Technique
In this work, flame spray technique was used to deposit coatings of C-Al-Si-Ti reinforced with different contents of Fe-Cr alloy on stainless steel surfaces to protect these surfaces from corrosion due to their continuous exposure to mechanical stresses and high temperatures. Spray parameters, mainly spray angle of 90°, spray distance of 15-20cm between the gun nozzle and the sample to be coated, a particle speed of up to 100 m/s, and a melting point exceeding 1200°C, were controlled to develop much more homogeneous and dense microstructures. The hardness of the coated surfaces was determined and found to enhance, whereas both porosity and water adsorption were found to decrease, indicating an improvement in coating adhesion and a reduction in structural defects. The results also showed a decrease in thermal conductivity as a result of increased dispersion of heat carriers (Fe-Cr) within the structure. Therefore, an optimal ratio of the reinforcing material was determined to achieve a balance between mechanical strength and thermal efficiency, making these coatings good candidates for engineering applications operating in harsh environments that require high resistance to corrosion and thermal stresses.
Mechanical Characteristics of Al-Si Casting Alloys Reinforced with SiC Nanoparticles
In this work, composite materials were prepared from aluminum-silicon (Al-Si) alloy (A356) reinforced with silicon carbide (SiC) nanoparticles with different percentage volumetric contents (from 0 to 5 vol.%) using casting method with mechanical stirring. Results of the transmission and scanning electron microscopy (TEM and SEM) showed inhomogeneous distribution of the SiC nanoparticles as dense clusters at high contents, which caused a degradation in the mechanical properties despite the increasing content of the reinforcing material (SiC nanoparticles). The Brinell hardness, yield strength, and ultimate tensile strength (UTS) were determined and compared to the unreinforced fundamental sample (0 vol.% SiC). The enhancement in these properties is attributed to the grain crystallinity with minimum size of 16 μm as well as strengthening mechanisms, whereas the porosity and particle clusters caused the mechanical properties to degrade when the optimum content of the reinforcing material (SiC nanoparticles) is exceeded as the fracture mode converts from completely ductile to a mix of ductile-brittle with dominant brittleness.
Synergistic Microporosity and CNT Integration in Carbon Electrodes for Dense Energy Storage in Aqueous Electrolytes
This work is an attempt to overcome the major challenge of the supercapacitors, which is the low energy density when compared to the batteries, throughout a proposed design of a hybridized carbon electrode combining the super microporosity and high electrical conductivity. The proposed strategy depends on the incorporation of carbon nanotubes (CNTs) at different percentage weights in a carbon matrix richen with pores smaller than 2 nm and derived from zinc ferrite frames by sol-gel method. This hybridization leads to the formation of a conductive network from CNTs working as highways for electrons while the carbon matrix maintains high specific surface area allowing the accumulation of ions from an aqueous electrolyte (Li2SO4). The practical significance of the proposed design is represented by its ability to bridge the gap between high energy densities of batteries and high power densities of conventional capacitors, with safe operation and low cost using aqueous electrolytes, as a promising solution for intensive energy storage applications.
Tailoring Interface-Induced Chirality in Synthetic Antiferromagnets for Next-Generation Spintronics through Strategic Heavy Metal Layer Optimization
This study explores the possibility of designing induced chirality at the interfaces in the synthetic antiferromagnetics (SAFs) throughout enhancing the heavy metal layer in the multilayer structures based on these materials for the applications of the next generation spintronics. This study considers the spin-orbit interaction (SOI) and Dzyaloshinskii-Moriya Interaction (DMI) to achieve control of spin current flow direction and spinal structures such as skyrmions. Results showed that platinum can produce higher DMI energy density of 1.3 mJ/m2 at layer thickness of 35 μm when compared to tantalum and tungsten. The optimized model of the multilayer structure showed velocities up to 103 m/s at low threshold current density of 1.2x1011 A/m2 with superiority over the standard model. These models allow the development of ultrafast and low-energy magnetic random-access memories (MRAM) for neural computers and new generations of effective spintronics.
Effect of Annealing Temperature on Physical Properties of Xerogel Structures Prepared by Cryogenic Compression Technique
In this work, xerogel materials were synthesized by the cryogenic compression technique and the effects of annealing temperature in the range of 100-1000°C on their physical properties were introduced and studied. Results showed that the porosity continuously decreases from its maximum at 85% to its minimum at <15% with increasing temperature due to the merging, sintering, and collapse of porous structure. An inverse relationship between porosity and relative hardness was observed as the hardness at 1000°C increased by 8 times than its value at 100°C. The optical transparency of the synthesized xerogels showed a nonlinear behavior as it increased from <5% to 85% at 400°C and then sharply decreased to <15% at high temperatures (800-1000°C) due to the collapse of pores and formation of crystalline phases and defects within the structure. These results present an important understanding for the relationship between heat treatment (annealing) and xerogel characteristics, which assists in the preparation of xerogel materials for specific applications such as insulation or catalysis.
Calculation of Mass Stopping Power of Alpha Particles in Human DNA Molecule Using Bragg's Rule against SRIM Simulation
The mass stopping power in different elements, molecules, and human tissues has been a subject of theoretical and applied sciences. They are very interested in mass stopping power because it characterizes how much energy a particle will lose as it passes through matter. In this paper, the mass stopping power for an alpha particle passing through DNA was calculated from 1 to 100 MeV using Bragg’s rule; these results matched closely with the SRIM-2015 simulation. The mass stopping powers of the elements making up the DNA were then calculated using the Bethe-Bohr formula, and the hydrogen element has the highest stopping power among all its elements. Absorbed dose and equivalent dose were also calculated for DNA, and there was a clear linear relationship between them and the mass stopping power. This work improves our understanding of how radiation deposits energy in genetic materials and helps support the use of these concepts in medical physics and assessing radiation risk.
Effect of Heat Treatment on Mechanical Behavior and Stabilization of Super-Elasticity of Nitinol Alloys Used in Smart Actuators
In this work, the effects of heat treatment on the mechanical behavior and superelasticity stability of nitinol alloys used in smart actuators were studied. Heat treatment was carried out at different temperatures via solution treatment, aging at 300°C, 400°C, and 500°C. Aging at 400°C showed the optimum results to achieve a balance between strength and elasticity as a clear plateau appeared to express the behavior of superelasticity while the austenitic phase transformation temperature reached 16°C. This ensured the existence of the austenitic phase at room temperature, which is the fundamental criterion for medical and industrial applications. Also, the results showed reasonable enhancement in the fatigue life for the samples aged at 400°C and 500°C as the enhancement was three times the as-prepared sample. This confirms the significance of the fine control of heat treatment parameters to produce nitinol alloys for the targeted applications.
Diffusion and Electrical Characteristics of Phosphorous-Doped Silicon Using Excimer Laser Pulses
In this work, p-type silicon samples were doped with phosphorus using pulses of an ArF excimer laser. In order to separate the effects of the gas and the adsorbed layers on doping characteristics, experiments were performed using two different procedures; doping in POCl3 ambient and doping using only adsorbed layers of POCl3 on the sample surface. The lowest sheet resistance was obtained for samples doped in POCl3 ambient. Activation energy for phosphorus evaporation from the silicon surface was determined. As well, electrical properties such as conductivity, carrier concentration and mobility were studied for the prepared samples at laser fluence of 2.5 mJ/cm2. Results presented could be considered successfully to develop semiconductor-doping using ultraviolet-wavelength lasers.
Gamma Radiation Shielding Characteristics of Nanocomposites Fabricated by Ultrasonic Waves-Assisted Cold Blending of Titanium Dioxide Nanoparticles and MDPE Matrix
In this study, hybrid nanocomposites were prepared from MDPE matrix reinforced with TiO2 nanoparticles with different weight fractions using cold blending method assisted by ultrasonic waves. The gamma radiation shielding characteristics of these nanocomposites were introduced and compared throughout measuring parameters such as mass and linear attenuation coefficients, half-value and tenth-value thicknesses, effective atomic number, effective electron density, and effective conductivity. Different radioactive sources with different energies ranging in 0.01-16 eV were used. Results showed that adding TiO2 nanoparticles to the MDPE matrix has reasonably enhanced the prepared nanocomposites’ capability for radiation shielding as the apparent density of the samples was increased with increasing TiO2 nanoparticles content in the composite samples. Consequently, the thickness required for shielding was reduced and attenuation parameters were increased especially at low energies where the photoelectric effect dominates. As well, samples with higher weight fractions of TiO2 nanoparticles showed higher values of effective atomic number and effective electron density that enhances scattering and absorption efficiency. In general, the prepared hybrid nanocomposites have confirmed their effectiveness as promising materials for radiation shielding applications with good control of their characteristics according to practical requirements related to weight, cost, and mechanical performance.
Photoluminescence Characterization of CuInS2 Quantum Dots Incorporated in Hybrid Structures for Light Emission Devices
In this work, hybrid multilayer structures containing CuInS2 quantum dots coated with ZnMgO shells and incorporated in conductive polymeric matrices (PEDOT:PSS and TFB) were prepared and characterized to develop eco-friendly toxic-free light emitting devices. Results showed that addition of formamidinium acetate (FAAc) lead to enhance the microstructure by reducing the agglomerations and surface roughness to support the homogeneity and connection of the grains. The existence of all organic and inorganic constituents was confirmed with dominant carbon bonds distinguishing the polymeric layers. The photoluminescence (PL) spectroscopy revealed a reasonable enhancement in the intensity of the emitted light as well as a slight redshift due to treatment with FAAc. The electrical characteristics showed the behavior of negative differential resistance at high voltages due to heating and charge collection effects at the interfaces. A maximum value of external quantum efficiency (EQE) of 10% was achieved at applied voltage of 6.5 V as the radiative recombination dominates. These results reveal that the FAAc-treated hybrid structures show promising optoelectronic characteristics for low-cost light emitting devices with high color purity and stable performance at high voltages.
Electrical and Optical Characteristics of Heterostructures Fabricated From Porous Silicon Structures Decorated with NiCo2O4 Nanoparticles by Solution Casting Method
In this work, Nickel cobaltite (NiCo2O4) nanoparticles were incorporated into a porous silicon (PSi) structures prepared on silicon substrates by photoelectrochemical etching (PECE) technique. The electrical characteristics of the fabricated photodetector showed that the heterojunction of NiCo2O4 nanoparticles concentration of 4x10-4 M exhibits higher photocurrent than the heterojunction of concentration of 4x10-4 M. The optoelectronic characteristics showed that the photodetector fabricated with NiCo2O4 concentration of 4x10-4 M is better than that with concentration of 4x10-4 M. The optimum photodetector showed a responsivity of 1.22 A/W, an external quantum efficiency of 2.32, and a detectivity of 14.37×10¹⁰ Jones. The response of the fabricated photodetectors was evaluated as a function of time and found dependent on the concentration (and hence layer thickness) of the NiCo2O4 nanoparticles as the device fabricated with lower concentration (smaller thickness) showed faster response.
Characterization of Periodic Ag/Al2O3/SiO2/Si Multilayer Structures by Spectroscopic Ellipsometry
In this work, multilayer structures based on consecutive thin films of silver (Ag) and alumina (Al2O3) were grown on silicon substrates by RF reactive sputtering technique. With a layer period containing consecutive Ag and Al2O3 films, the number of these periods was varied to introduce their effects on the optical characteristics of the fabricated structures. The spectroscopic ellipsometry was carried out on these structures to determine the ellipsometric parameters (amplitude ratio Ψ and phase shift difference Δ) as functions of incident light wavelength for three different incidence angles (60°, 70°, and 80°). Results showed that the larger number of periods resulted in a higher sensitivity to the incidence angle by the multilayer structure, which is very crucial for practical applications such as optical filters and photonic sensors as the thickness and structure of these layers are controlled to achieve certain optical response within a desired wavelength ranges.
Multifunctional Carbon Fiber–Graphene Epoxy Composites for Structural Health Monitoring under Dynamic Loading
In this work, multi-scale hybrid composite materials were fabricated from carbon fibers and graphene nanoplatelets mixed at different ratios and dispersed in epoxy resin matrix. The main mechanical characteristics (stress-strain) of these composite materials were determined and slight differences were observed with varying mixing ratios. The variation in electrical resistance of the fabricated composite samples was determined as a function of the applied mechanical stress at different frequencies of the multiple loading cycles. Approximately linear behavior was observed for all samples and hence the gauge factor was calculated and found to increase with applied stress and frequency. These results can be successfully used to design multi-functions composite materials for smart and self-health monitoring systems.
Study of Gamma Irradiation on FTIR and XRD of MWCNTs-Clay-TiO2 Nanocomposite
Structural and chemical analysis of gamma-irradiated green-synthesized TiO2–MWCNTs–Bentonite nanocomposite obtained by Melia azedarach leaf extract have been studied. Dose dependent changes in bonding configuration, crystallinity and functional groups were studied along with the impact of doses by gamma (25, 50, 75 and 100 kGy) in FTIR and XRD analyses. XRD data results showed that moderate irradiation doses (25–50 kGy) enhanced the formation of the TiO2 phase and interfacial adhesion among TiO2, MWCNTs, and clay matrices. These modifications produced an increase in lattice perfection and surface hydroxylation, which were essential for photocatalysis and adsorption. Higher doses (75–100 kGy), on the contrary, resulted in an incomplete amorphization and defect formation, with a significant bond scission comprising of both bond breaking and oxidation. The dual role of gamma irradiation, in increasing structure at mild doses and decreasing at higher levels indicates its application as a tunable tool for nanocomposite design. Technically, the tunable surface chemistry and crystallinity of irradiation as applied could serve as a promising way to adjust photocatalytic activity of the hybrid nanomaterials for environmental purification and photochemistry-responsive practices.
Fluorescence Characteristics of Random Gain Media Fabricated from Fluorescein Dye Containing Zinc Oxide Nanoparticles in Transparent Organic Hosts
In this work, ZnO nanoparticles with different weights (0.01-0.09 mg) were incorporated into a solution of 6x10-6 M Fluorescein dye dissolved in transparent resin in order to fabricate random gain media. The fluorescence and gain characteristics of these media were introduced when excited with a 405 nm laser source. The addition of ZnO nanoparticles to the Fluorescein dye dissolved in a transparent resin host leads to an observable enhancement in the fluorescence intensity of random gain media fabricated from such systems. The active role of ZnO nanoparticles as scattering centers can be observed by the enhanced optical feedback and optical gain of these media. The ZnO nanoparticles do not change the electronic structure of the Fluorescein dye and their effects specifically lie on scattering and re-absorption processes. The weights used in this work confirm that the random gain media did not cause quenching due to aggregation or excess absorption, therefore, significant losses were avoided. The accurate control of nanoparticles concertation in the random gain medium is an effective tool to control the emission or fluorescence characteristics to serve the practical purposes for which such random lasers are used.
Correlation of Properties-Structures in Polycrystalline Thin Film Solar Cells Using Light-Beam-Induced Current Mapping
Light-beam-induced-current (LBIC) measurements are providing a direct link between the spatial non-uniformities inherent in thin-film polycrystalline solar cells, such as CdTe and CIGS, and the overall performance of these cells. LBIC is uniquely equipped to produce quantitative maps of local quantum efficiency with relative ease. Spatial resolution of 1 μm at 1-sun intensity, and return to the same area after other measurements, is routinely achieved. A wavelength range of 638nm to 857nm is available with diode lasers. The LBIC measurements demonstrate that several types of effects that alter cell performance can be traced to specific local-area features. Examples of such effects include defects related to edges, grids, or scribes, spatial variations in alloying, and local changes due to high-temperature stress.
Composition Tuning of Silicon Nitride Nanomaterial Synthesized by Plasma-Assisted Deposition Technique
Composition tuning of silicon nitride nanostructures synthesized by plasma-assisted deposition technique was carried out in this work. The fractional composition of these nanostructures was tuned by varying the pressure of nitrogen gas used as reactive gas inside plasma chamber. The characterization tests included spectrophotometry in the UV, visible, and IR regions of electromagnetic spectrum. The fine control of preparation conditions can be used successfully to determine the structural composition of the final product, which would satisfy certain requirements and applications. Stoichiometric samples of silicon nitride (SixN1-x) were prepared with energy bandgap varying within 4.97-5.39 eV as the gas mixture flow rate was varied within 2-20 Ltr/s.
Particle Size-Dependent Energy Conversion in Plasmonic Nanostructures for Photothermal Catalysis Applications
This work examines the influence of nanoparticle size and morphology on the photothermal catalytic behavior of gold and silver nanostructures. Localized surface plasmon resonance (LSPR) effects were tuned to optimize light absorption and heat generation. A tight and nonlinear relation between particle diameter and optical properties was confirmed as the particles with diameters in the range 25-35 nm have achieved the maximum efficiency of light absorption, making this range optimum to convert the photons into condensed local heat. A radical transformation was disclosed when the particle diameters exceed 60 nm as the scattering dominates the absorption. Results revealed that he particle diameter can change the maximum temperature as well as the heat distribution in the surrounding medium. Particles in the range 20-40 nm produce sharp thermal concentration, which is localized at the surface interface (<10 nm from the surface). The larger particles (>40 nm) exhibit a unique phenomenon (secondary hot spots) at the far-field range, which extends the effective thermal range in the catalyst. Finally, the reaction rate constant does not continuously increase with decreasing the particle diameter as a precise balance between the surface-to-volume ratio and photothermal conversion efficiency, whose maximum was obtained for the particle diameter of 40 nm.
This study explores multifunctional epoxy-based composites reinforced with carbon fibers and graphene nanoplatelets. The addition of graphene enhances both electrical conductivity and interfacial bonding, enabling real-time strain sensing capabilities. Dynamic mechanical analysis reveals improved damping performance, while fatigue testing confirms enhanced durability. The integration of sensing and load-bearing functionality paves the way for self-monitoring aerospace and automotive structures.
Analysis of Dynamic Covalent Crosslinks in Self-Healing Conductive Polymers for Flexible Electronics
A new class of conductive, self-healing polymers based on dynamic covalent crosslinking chemistry is presented. The material exhibits autonomous healing at room temperature, recovering up to 95% of its electrical conductivity and tensile strength after damage. Rheological and spectroscopic analyses confirm reversible bond exchange under mild conditions. Demonstrations in stretchable circuit prototypes highlight its potential in wearable electronics, soft robotics, and smart sensing devices.
Reinforcement of Ultra-High-Temperature Zirconium Diboride Composites with Silicon Carbide Nanowires for Aerospace Applications
The development of ultra-high-temperature ceramics (UHTCs) is critical for hypersonic and aerospace systems. This work presents the fabrication and characterization of ZrB₂–SiC nanowire composites with improved thermal stability and oxidation resistance. Hot pressing and spark plasma sintering were used to achieve dense microstructures with controlled nanowire dispersion. Mechanical testing at 1800°C demonstrates enhanced flexural strength and thermal shock resistance, attributed to crack deflection and load transfer mechanisms. These composites show promise for reusable thermal protection systems and high-enthalpy propulsion components.
Control Thermomechanical Processing via Synergetic Effect of Strength-Ductility of Advanced Steels
This study investigates the role of grain boundary engineering (GBE) in improving the mechanical performance of advanced high-strength steels. Through controlled thermomechanical processing, a tailored grain boundary network is achieved, optimizing the balance between strength and ductility. Electron backscatter diffraction (EBSD) reveal the formation of low-energy boundaries that suppress crack propagation. Mechanical testing demonstrates up to a 25% improvement in elongation without compromising yield strength. These findings highlight GBE as a viable route for developing next-generation structural alloys with superior performance.
IJM027 Second Harmonic Generation of Polymorphic Bismuth Halide Structures
In this work, synthesis and utilization of hybrid materials from the Et3​NH+, Bi3+, and Br− components for second harmonic generation (SHG) are presented. Two different phases that both had the exact same chemical composition, (Et3​NH)3​Bi2​Br9​, were crystallized. These two phases were noteworthy because they possessed contrasting crystal structures: one phase was noncentrosymmetric and could generate an SHG signal, while the other phase was centrosymmetric and lacked SHG capability.
Copyright (c) 2025 IRAQI JOURNAL OF MATERIALS https://creativecommons.org/licenses/by/4.0
IJM026 Structural and Morphological Characteristics of PPY-PANI Composite Thin Films by Solution Mixing Method
In this work, the structural and morphological characteristics of pure polypyrrole (PPY), polyaniline (PANI), and their blends in varying ratios were studied. The X-ray diffraction (XRD) analysis revealed distinct diffraction peaks corresponding to the characteristic structures of PPY, PANI, and their blends (PPy-PANI), indicating successful composite formation and phase interactions. Field-emission scanning electron microscopy (FE-SEM) results showed porous, interconnected morphologies in composites, which enhance surface area and gas adsorption sites compared to pure polymers. Such enhancement is very useful for gas sensing applications of PPY/PANI thin film composites at elevated temperatures.
IJM017 Influence of FeO Layer Thickness on Characteristics of FeO/Porous Silicon Heterojunction Photodetectors
This work investigates the influence of iron oxide (FeO) layer thickness on the optoelectronic performance of FeO/porous silicon (PSi) heterojunction photodetectors. Devices with FeO thicknesses of 100, 200, and 300 nm were fabricated and evaluated in terms of dark current, photocurrent, sensitivity, spectral responsivity, external quantum efficiency (EQE), specific detectivity (D*), noise-equivalent power (NEP), and temporal response. The results reveal that the FeO thickness plays a decisive role in charge transport, carrier recombination, and optical absorption. A 200 nm FeO layer exhibited optimal behavior, achieving the highest responsivity (0.55 A/W at ~550 nm), EQE (~1.25%), and detectivity (~1.0×10¹³ Jones), along with the lowest NEP (~4×10⁻¹² W). While thinner layers (100 nm) suffered from poor light absorption and incomplete passivation, thicker layers (300 nm) introduced higher series resistance and trap states, degrading performance. The findings demonstrate that precise control of FeO thickness is critical for optimizing FeO/PSi heterojunction photodetectors for visible light applications.
IJM020 Effects of Nanoparticles Content on Gamma-Ray Shielding Parameters of Magnetite/PDMS Nanocomposites
In this work, the effects of weight percentage content of magnetite nanoparticles on the gamma-ray shielding parameters of the nanocomposite fabricated from these nanoparticles in PDMS matrix were determined and analyzed. These parameters include the linear attenuation coefficient (LAC), the mass attenuation coefficient (MAC), the half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), and effective atomic number (Zeff).
IJM025 Characteristics of Cobalt Ohmic Contacts Fabricated on Silicon Surface by Laser-Induced Diffusion
This study investigates the fabrication and characterization of cobalt Ohmic contacts on n-type silicon substrates using laser-induced diffusion. A Q-switched Nd:YAG laser was used to provide a low thermal budget method for forming a conductive CoSi2 layer. Results demonstrate a critical relationship between the number of laser pulses and the electrical properties of the contact. A significant decrease was observed in sheet resistance and a corresponding increase in electrical conductivity up to an optimal number of pulses. This is attributed to the enhanced diffusion and activation of dopant atoms, leading to a high concentration of free charge carriers. However, excessive laser pulses beyond this optimal range result in a degradation of electrical properties, as evidenced by a rise in sheet resistance. This is due to the formation of crystallographic defects that act as scattering centers, thereby reducing carrier mobility. The findings underscore the importance of precise process control to achieve high-performance Ohmic contacts while avoiding thermal damage.
IJM015 Influence of Zirconium Content on Mechanical Strength and Hardness of AlCuNiZr Alloys Fabricated by Shockwave-Assisted Technique
This report presents a comprehensive analysis of the mechanical properties of AlCuNiZr alloys fabricated using a shockwave-assisted technique, with a particular focus on the influence of varying Zr content. The study demonstrates that this non-equilibrium processing route produces ultrafine grain structures, high dislocation densities, and strong interfacial bonding. Zirconium is shown to synergistically enhance these effects by promoting further grain refinement and precipitation strengthening through the formation of Al3Zr and Ni7Zr2 intermetallic compounds. The results indicate that the mechanical strength of the alloy exhibits a non-linear relationship with zirconium content, peaking at 0.5 wt.% due to the optimal balance of grain refinement and precipitation strengthening. Exceeding this concentration can lead to a decrease in strength, likely from precipitate coarsening. The findings underscore the potential of combining shockwave processing with precise compositional control to design advanced AlCuNiZr alloys with superior mechanical performance for demanding applications in aerospace and automotive sectors.