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Electrophysical and Physical-Chemical Properties of Ohmic Contacts to III-N Compounds
摘要： Experimental data on studying ohmic contacts based on single-layer and multilayer metallizations on GaN and (In, Al, Ga)N solid solutions are analyzed. The contact resistance of the Ti/Al/Mo/Au and Ti/Al/Mo/W/Au metallizations on undoped GaN is studied. The dependences of the contact resistance on the GaN surface treatment before the metallization and on the metallization annealing regimes are investigated.
关键词： gallium nitride,surface treatment,(AlInGa)N solid solutions,ohmic contacts,metallization,charge neutrality level
更新于2025-09-19 17:15:36
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Effect of anode surface treatment by oblique ion bombardment method on Organic light-emitting diodes performance
摘要： In this work, The influence of oblique ion bombardment treatment of the surface of indium tin oxide (ITO) thin films, on the surface parameters of the film and then the performance of organic light-emitting diodes (OLEDs) has been investigated. Both commercially available and uniquely fabricated ITO substrates which were deposited by electron beam evaporation method have been employed. The ITO surface characteristics have been investigated by atomic force microscopy (AFM), X ray diffraction (XRD) and UV-Vis-NIR spectrophotometer. Then a typical OLED device was fabricated on different ITO surfaces and characterized by Keitley 2450 and JAZ spectrometer. The results show that after anode surface treatment by means of oblique Argon ion bombardment method, surface roughness is extremely decreased, which resulted in increasing current and power efficiencies and also there was no evidence of ohmic junctions before driving voltage. The maximum ohmic resistance, current and power efficiencies were 371 MΩ, 6.4 cd/A and 0.91 cd/w, respectively. Also it is found that local non-emissive area or dark spots creation reduced for treated surface device. These findings provide a simple way to effectively reduce the roughness of the ITO films as anode to be applied in optoelectronic devices such as OLEDs.
关键词： Surface roughness,Organic light emitting diodes,Oblique ion bombardment,ITO,Surface treatment,Dark spot
更新于2025-09-19 17:13:59
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Titanium fixture implants treated by laser in dentistry: Review article
摘要： Surface modifications of titanium implants are necessary for predictable implant success, especially in circumstances where the bone is of low density or when rapid implant loading protocols are needed. Currently, overwhelming data regarding different surface modification techniques have been documented; among these, lasers stand out as a clean and effective modality. This article aims to review the studies related to laser-treated titanium implant surface and laser metal sintered titanium implant surface.
关键词： Surface treatment,Laser,Implant,Titanium
更新于2025-09-19 17:13:59
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The Effect of Titanium (IV) Chloride Surface Treatment to Enhance Charge Transport and Performance of Dye-Sensitized Solar Cell
摘要： In this study, the photovoltaic and electrochemical characteristics of the dye-sensitised solar cell (DSSC) after Titanium (IV) Chloride (TiCl4) treatment on a TiO2 photoelectrode were investigated. Photoelectrodes of untreated, pre-TiCl4 and post-TiCl4 treatment were prepared to form a complete DSSC. The photoelectrode was sensitised in 40mM of TiCl4 solution at 80 °C for 30 minutes, and then it is sintered at 500 °C. The morphology of photoelectrodes has been studied using FESEM, and it was found that, after TiCl4 treatment, the particle necking and particle size of TiO2 nanoparticles were increased significantly. Therefore, it improved the electron transfer path on the TiO2 layer. Subsequently, the the light absorption intensity after post-TiCl4 treatments was increased due to strong adhesion and homogeneity of the TiO2 layer on the FTO substrate, which results in higher current density and photon-conversion efficiency by 18.95 mAcm-2 and 8.03% when compared to an untreated electrode at 12.1 mAcm-2 and 4.08% (increment of 56.7% and 96.9%), respectively. Electrochemical impedance spectroscopy used to study the internal electrochemical characteristics of DSSC after the treatment. Thus, it proves that the treatment suppresses the charge recombination between TiO2 and the electrolyte interface by increasing charge transfer resistance after post-TiCl4 treatment by 24.06Ω from 16.11Ω for untreated photoelectrodes (increment of 49.39%). The electron lifetime also improved from 0.4 to 1.59 ms, which results in the enhancement of charge collection efficiency after post-treatment by 31.09% compared to the untreated electrode. Improvement of charge collection efficiency indicated that the TiCl4 treatment had played an important role in charge separation and charge collection on the TiO2 and electrolyte interface of DSSC.
关键词： charge transport,DSSC surface treatment,TiCl4,charge collection efficiency (CCE)
更新于2025-09-19 17:13:59
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Achieving a strong polypropylene/aluminum alloy friction spot joint via a surface laser processing pretreatment
摘要： Strong metal/non-polar plastic dissimilar joints are highly demanded for the lightweight design in many fields, which, however, are rather challenging to achieve directly via welding. In this study, we designed a laser processing pretreatment on the Al alloy to create a deep porous Al surface structure, which was successfully joined to the polypropylene (PP) via friction spot welding. A maximum joint strength of 29 MPa was achieved, the same as that of the base PP (i.e. the joint efficiency reached 100%), much larger than ever reported. The joining mechanism of the Al alloy and the PP was mainly attributed to the large mechanical interlocking effect between the laser processed Al porous structure and the re-solidified PP and the formation of chemical bond at the interface. The deep porous Al surface structure modified by laser processing largely changed the Al?PP reaction feature. The evidence of the C?O?Al chemical bond was first time found at the non-polar plastic/Al joint interface, which was the reaction result between the oxide on the Al alloy surface and thermal oxidization products of the PP during welding. This study provides a new way for enhancing metal-plastic joints via surface laser treatment techniques.
关键词： Surface treatment,Polymer,Interface,Hybrid joint,Metal,Friction stir welding
更新于2025-09-19 17:13:59
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Morphological and Chemical Characterization of Laser Treated Surface on Copper
摘要： Electron multipacting and electron cloud have been identified as being the major limiting factors for the beam quality or for the cryogenic system of high-intensity positive particles accelerators. Among conditioning operational techniques and other surface structuration techniques used to decrease the Secondary Electron Yield (SEY) of surfaces, laser surface treatment is a promising method to treat in situ and at atmospheric pressure copper surface of the vacuum chamber. Here, pulsed laser irradiation of copper in parallel lines pattern led to the local ablation and deposition of aggregates of copper particulates on the surface. Tests undertaken at CERN have shown that the modification of the surface morphology by creating roughness at different scales induces a decrease of the SEY by geometrical effects. Nevertheless, the mechanical strength and dust generation of the treated surface have not been addressed yet. In this work, a qualitative analysis of the multi-scale description of the surface morphology was carried out. Scanning Electron Microscopy (SEM), Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDS) were used to investigate morphological characterization such as size and shape of the particulates, chemical composition, metallographic structures and phase transformation on the laser-processed surface. SEM and FIB examinations showed that the surface morphology depends on the local laser energy irradiating the surface and especially, relatively to the ablation threshold. TEM analysis revealed chemical composition and crystalline configuration of the treated material and helped to identify the laser modified and oxidized areas. A variety of superficial structures were observed. Potential vulnerable structures have been identified as oxidized matter redeposited on the ablated near surface. Material continuity and composition play a major role in the mechanical integrity of the generated surface morphology. The adherence of the created structures was assessed analyzing the origin of the dust extracted after mechanical stress.
关键词： microstructural observations,morphological characterization,laser surface treatment,surface structuration
更新于2025-09-16 10:30:52
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Performance analysis of laser-treated hot forging dies with WC-Co-Cr
摘要： The service life of hot forging dies was evaluated after being subjected in a double-layer surface treatment. The dies were laser treated, using WC-Co-Cr powder, and then surface nitrided. Previously, the integrity of the layers was proven metallographically. Information about the properties of the surface was measured in order to be used later for the wear calculation. The performance of the treated die compared with the normal one was first assessed by FEM wear simulation. The areas with increased wear were determined, and with the aid of an analytical model, the total wear was predicted after predetermined number of forging cycles. Later, forging dies were manufactured, surface treated, and utilized in real production environment. The results suggested an improvement of 41% and 94% for the different forging trials which also is in good agreement with the simulation results.
关键词： WC-Co-Cr,Laser,Multilayer,Wear,Surface treatment,FEM,Hot forging
更新于2025-09-16 10:30:52
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Laser surface modification of structural glass for anti-slip applications
摘要： The use of soda-lime silicate glass as a structural element has become frequent in modern buildings. The load-bearing applications of glass in floors, footbridges, terraces, or stairs require an optimal combination of non-slippery properties of the surface, element weight, and strength, and structural glazing can be compromised by the incorporation of laser surface patterned ornamental motifs. Laser surface modification has significant advantages for selective surface area modification; nevertheless, the mechanical performance of the processed glass remains unknown, which precludes reliable structural calculations and employment in construction. In this study, we investigated the surface modification of annealed and heat-strengthened glass via CO2 laser scanning for the production of rough anti-slip surfaces. The surface roughness and the reduction of the bearing load strength were quantified. Slip resistance-enhanced surfaces with roughness values (Rz) above 20 μm and characteristic bending strength preservation up to 74% were obtained. The results pave the way for the use of laser surface-modified plates in laminated glass elements with optimized strength calculation and weight reduction.
关键词： CO2 laser,Heat strengthened glass,Surface treatment,Structural glass
更新于2025-09-16 10:30:52
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Microstructural characterization of Inconel 718 alloy after pulsed laser surface treatment at different powers
摘要： An annealed Inconel 718 alloy was surface-treated by pulsed laser at three different powers (100, 50 and 25 W). Microstructural changes induced by the laser treatments were characterized by use of electron backscatter diffraction and electron channeling contrast imaging techniques. Results show that both annealing twins and strengthening precipitates profusely existing in the as-received specimen are dissolved at elevated temperatures during the laser irradiation. Meanwhile, in the melting zone (MZ), densities of low angle boundaries (LABs) are greatly increased with a large number of Laves phases preferentially distributed along such LABs. For different specimens, widths and depths of their MZs are found to be gradually reduced with decreasing the laser powers. Orientation analyses reveal that the columnar grains in the MZ of the 100 W specimen could inherit orientations existing in the matrix while lower laser powers promote the formation of more nuclei with scattered orientations to grow to be granular grains in the MZ. Hardness tests reveal that the MZs of all laser-treated specimens are softer than the matrix probably due to both precipitate dissolution and grain coarsening.
关键词： pulsed laser surface treatment,hardness,grain boundaries,Inconel 718 alloy,electron backscatter diffraction
更新于2025-09-16 10:30:52
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Mechanism of improved luminescence intensity of Ultraviolet Light Emitting Diodes (UV-LEDs) under thermal and chemical treatments
摘要： In this work, the influences of thermal annealing and chemical passivation on the optical and electrical properties of ultraviolet light-emitting-diode (UV-LED) were investigated. The electroluminescence (EL) intensities of the LEDs under KOH treatment and thermal annealing increased by 48% and 81%, respectively compared to as-fabricated LED under current level of 10 mA. Cathodoluminescence (CL) mapping of UV-LEDs confirmed no variation of the density of the non-radiative recombination centers after surface treatments, and no obvious change in surface morphology was identified due to lacking of energy for surface atom migration. However, Raman spectroscopy indicates a relaxation of compressive strains inside the thin film after both thermal and chemical treatments, and conductive atomic force microscopy (c-AFM) also illustrated reduced leakage current after KOH passivation, which are responsible for the improved luminescence properties of UV-LEDs.
关键词： surface treatment,UV-LED,electroluminescence,strain relaxation
更新于2025-09-12 10:27:22