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How the Laser Beam Energy Distribution Effect on Laser Surface Transformation Hardening Process; Diode and Nd:YAG Lasers
摘要： The laser surface transformation hardening (LSTH) of AISI 4130 steel by 1600 W high power diode laser (HPDL) and 700 W Nd:YAG lasers were investigated in this present study. The distribution influence, and the lasers beam shape; Top-hat in the HPDL and Gaussian distribution in the Nd:YAG laser, have been studied on the geometrical dimensions, and micro-hardness in hardened area (i.e.; depth, width, and angle of entry of hardened profile), micro-hardness deviation (MHD) from the row steel in geometric dimensions, and the ferrite’s percentage in hardened layer center. Microstructure evaluation of the laser hardened areas were performed by FE-SEM and optical microscopy. Based on the results, maximum hardness was created with the HPDL, and the geometrical dimension was more than the Nd:YAG laser. Also, MHD, and minor phase of ferrite in the HPDL laser surface hardening than the hardened layer in Nd:YAG laser, which is related to the higher laser absorption. Results show that, the hardened zone of HPDL is about 698 HV0.1 with 1.02 mm depth, while for Nd:YAG laser is about 698 HV0.1 with 0.98 mm depth. Comparing the results with the furnace hardening heat treatment (FHT) demonstrated that the hardness in diode laser and Nd:YAG laser hardening are 1.38 and 1.22 times of the hardness in FHT, respectively.
关键词： Industrial lasers,AISI 4130 low alloy carbon steel,Beam shape,Laser surface treatment
更新于2025-09-11 14:15:04
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Evaluation of the Effect of Ultraviolet Light Excitation during Characterization of Silicon Carbide Epitaxial Layers
摘要： The scanning of Silicon Carbide (SiC) epitaxy wafers for defects by ultraviolet (UV) laser or lamps is widely prevalent. In this work, we document the effects of UV light excitation on the SiC epitaxy material. An increase in background photoluminescence (PL) is observed after repeated scans. The effect of this increase on defect detection is shown. Optimal surface treatments to recover the material back to the original state are demonstrated. Further, some surface treatments are proposed which reduce the effect of the UV light excitation and prevent to a large extent the rise in background PL.
关键词： photoluminescence,surface treatment,ultra-violet excitation,surface passivation,defect scanning
更新于2025-09-09 09:28:46
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7.5: Reduction of Visual Fatigue caused by Surface Reflection of Displays
摘要： Previous report on ergonomics experiment has verified that task under ambient vision stress illumination can be reduced effectively by introducing AG or AGAR to LCDs. In this paper, we analyzed the contrast of LCD of surface treatment of AG, AR and AGAR under ambient illumination. By using AGAR surface treatment, the contrast can be improved to higher than 10, a necessary minimum contrast for comfort reading. We believe this as one reason of the vision stress reduction of LCD of AGAR treatment.
关键词： anti-glare,ergonomic,Vision stress,legibility,anti-reflection,sparkle,surface treatment
更新于2025-09-04 15:30:14
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Structural and optical properties of sulfur passivated epitaxial step-graded GaAs <sub/>1-y</sub> Sb <sub/>y</sub> materials
摘要： The impact of bulk and surface defect states on the vibrational and optical properties of step-graded epitaxial GaAs1-ySby (0 ≤ y ≤ 1) materials with and without chemical surface treatment by (NH4)2S was investigated. Tunable antimony (Sb) composition GaAs1-ySby epitaxial layers, grown by solid source molecular beam epitaxy (MBE), were realized on GaAs and Si substrates by varying key growth parameters (e.g., Sb/Ga ?ux ratio, growth temperature). Raman and photoluminescence (PL) spectroscopic analysis of (NH4)2S-treated GaAs1-ySby epitaxial layers revealed composition-independent Raman spectral widths and enhanced PL intensity (1.3×) following (NH4)2S surface treatment, indicating bulk defect-minimal epitaxy and a reduction in the surface recombination velocity corresponding to reduced surface defect sites, respectively. Moreover, quanti?cation of the luminescence recombination mechanisms across a range of measurement temperatures and excitation intensities (i.e., varying laser power) indicate the presence of free-electron to neutral acceptor pair or Sb-defect-related recombination pathways, with detectable bulk defect recombination discernible only in binary GaSb PL spectra. In addition, PL analysis of the short- and long-term thermodynamic stability of sulfur-treated GaAs1-ySby/Al2O3 heterointerfaces revealed an absence of quanti?able atomic interdiffusion or native oxide formation. Leveraging the combined Raman and PL analysis herein, the quality of the heteroepitaxial step-graded epitaxial GaAs1-ySby materials can be optimized for optical devices.
关键词： molecular beam epitaxy,optical properties,structural properties,sulfur passivation,Raman spectroscopy,surface treatment,photoluminescence spectroscopy,GaAs1-ySby
更新于2025-09-04 15:30:14
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Effect of surface treatment of printed Ag Schottky contacts on n-GaN epitaxial layers using Ag nanoink: Two dimensional characterization by scanning internal photoemission microscopy
摘要： We report the basic electrical characteristics of Ag Schottky contacts printed on n-GaN epitaxial wafers using Ag nanoink with surface treatment using HCl or an organic solvent. The Ag Schottky contacts treated with HCl showed better current–voltage characteristics and a larger Schottky barrier height than those treated with the organic solvent. Scanning internal photoemission microscopy revealed that the HCl-treated samples exhibited a higher uniformity owing to their higher wettability to the Ag nanoink and electrodes than the organic-solvent-treated samples. These results indicate that the removal of surface oxide layers using HCl is effective even though the GaN surface is printed and annealed in air.
关键词： Ag Schottky contacts,n-GaN,surface treatment,Ag nanoink,scanning internal photoemission microscopy
更新于2025-09-04 15:30:14