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Tuning the wettability and photocatalytic efficiency of heterostructure ZnO-SnO2 composite films with annealing temperature
摘要： ZnO-SnO2 composite films were spin-coated and annealed at different temperatures. The characteristics of the films were studied by using XRD, FESEM, AFM, FT-IR and UV–Vis spectroscopy. The wetting nature of the films was assessed by observing the water contact angle by sessile drop method. It was seen that the annealing temperature had a significant role in increasing the surface roughness. This leads to a change in water contact angles which are consistent with the Wenzel state of wetting. Photodegradation of model pollutants in liquid phase (cationic methylene blue, anionic methyl orange) and solid phase (octadecanoic acid) was performed to measure the photocatalytic efficiency of the films. The enhanced photocatalytic efficiency of films annealed at higher temperatures is due to better crystallinity and formation of heterostructure that inhibits the re-combination of charge entities (electron-hole).
关键词： Roughness,Contact angles,Heterostructures,Photocatalysis
更新于2025-11-19 16:56:35
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Impact of surface micromorphology and demineralization severity on enamel loss measurements by cross-polarization optical coherence tomography
摘要： Objectives: Optical Coherence tomography (OCT) is a promising clinical imaging technology for quantitative and objective assessment of dental erosion. We aimed to determine the influence of enamel surface roughness and demineralization severity (by erosive challenge) on dental surface loss measurements by cross-polarization OCT (CP-OCT). Materials and methods: Human enamel specimens were prepared with three surface roughness levels (very rough, rough and polished; n = 10 each). They were evaluated using CP-OCT and optical profilometry (gold standard) at baseline, and after 1, 2, 4, 6, 8, 16 and 24 h of erosion demineralization. The effects of roughness and demineralization on enamel loss were analyzed using ANOVA (alpha = 0.05). Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to evaluate inter-method agreement and intra-examiner repeatability. Results: CP-OCT surface loss measurements did not significantly differ with the changes in enamel surface roughness (p = 0.27). Among demineralization severities, CP-OCT surface loss measurements at 1, 2, 4 and 8 h did not differ among each other, but they showed significantly lower enamel loss than 16 and 24 h; 6 and 16 h were significantly lower than 24 h (p < 0.05). Overall, CP-OCT and optical profilometry measurements did not differ (p = 0.73); however, ICC was relatively low (ICC = 0.34). Enamel loss estimation by CP-OCT presented an error of approximately ± 150 μm compared to profilometry. Intra-examiner repeatability with CP-OCT was excellent (ICC = 0.98). Conclusions: Enamel roughness did not affect CP-OCT measurements. The estimated error of CP-OCT measurements limited the appropriate assessment of enamel erosion surface loss, in the magnitude simulated in this study. Clinical relevance: Enamel thickness measurement by CP-OCT presents potential as an objective method for monitoring dental erosion lesions; however, its use may be limited for the assessment of the initial stages of enamel surface loss by erosion.
关键词： Tooth wear,Optical coherence tomography,Surface roughness,Enamel,Dental erosion,Demineralization
更新于2025-09-23 15:23:52
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Effect of temperature on digital images of speckle patterns generated by a metallic rough surface
摘要： It is well known that roughness can be inferred from digital images of speckle patterns generated by illuminated rough surfaces, by analyzing parameters such as fractal dimension, lacunarity and correlation, to cite a few. In this article, we investigate the effect of temperature on the speckle pattern generated by the light scattered from a metallic rough surface. We show that fractal dimension is less sensitive to temperature changes than are lacunarity and correlation, and provide information about which method is more suitable for processing the speckle patterns produced by rough surfaces under temperature variation.
关键词： Speckle pattern,Fractal dimension,Correlation,Roughness,Lacunarity,Temperature
更新于2025-09-23 15:23:52
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Theory for IMPS on Rough and Finite Fractal Dye Sensitized Solar?Cell
摘要： A generalized theoretical model of intensity modulated photocurrent spectroscopy (IMPS) for the random morphology in a dye sensitized solar cell (DSSC) under uniform illumination is developed. The generalized IMPS expression for the disordered semiconducting/conducting glass interface of a DSSC is obtained in term of power spectral density of roughness. Influence of surface roughness on the dynamic response of DSSC originate due to the coupling of characteristic phenomenological and morphological length scales. A detailed analysis of IMPS response is performed over finite self-affine fractals to highlight roughness induced anomalies and cause of photocurrent enhancement. The IMPS of a rough DSSC exhibit three characteristic frequency regimes: lifetime of charge carrier dependent low frequency regime, surface irregularity dependent intermediate power-law regime and diffusion controlled high frequency regime. Finally, our theory facilitates the understanding of dynamics and kinetics of charge carriers under the influence of ubiquitous surface disorder.
关键词： DSSC,charge transport,fractal,surface roughness,IMPS
更新于2025-09-23 15:23:52
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Formation of 45° Silicon (110) Surface Using Triton X- <i>n</i> Surfactants in Potassium Hydroxide for Infrared Applications
摘要： Silicon (Si) micromirrors are an integral feature for many micro-optomechanical systems (MOEMS). Such mirrors are generally wet etched in alkaline solution at elevated temperature. For 90? beam steering applications, 45? slanted Si (110) plane is the prime choice fabricated with the incorporation of tensioactive surfactants. Here, Triton-Si and Triton-hydroxide (OH?)/H2O interaction using varying hydrophilic chain length Triton (X-45, X-100 and X-405) were investigated. The surfactant concentration was varied from 0 to 1000 ppm in potassium hydroxide (KOH). Triton molecules were shown to adsorb preferentially on (110) than on (100) surface. Longer chain length Triton hampered OH? access to Si surface resulting in slower etch rate. In contrast, contact angle measurement suggested that shorter Triton interfaced better with Si surface. Later, Si wafers etched in Triton 10 ppm – KOH were examined. The measured output for (110)X-45, (110)X-100, (110)X-405 and polished Si wafer reference (Rq < 5?) mirrors were 0.58, 0.76, 0.72 and 1.25 mW, respectively. Subsequently, Si-SiO2 thin film in [HLHL]2-substrate configuration was fabricated. Broadband micromirror for use in 3.0–5.5 μm spectrum range was experimentally realized with reflected efficiency of 73%.
关键词： wet etching,optical measurement,Silicon micromirrors,Triton X-n,surface roughness,potassium hydroxide,surfactants
更新于2025-09-23 15:23:52
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Characteristics of Vanadium Oxide Thin Films Fabricated by Unbalanced Magnetron Sputtering for Smart Window Application
摘要： Vanadium oxide (VOx) thin films were deposited by an unbalanced magnetron (UBM) sputtering system with a vanadium metal target and O2 reaction gas, and thermally treated at various annealing temperatures. In this work, the structural, electrical, and optical properties of the fabricated VOx films with various annealing temperatures were experimentally investigated. The UBM sputter grown VOx thin films exhibited amorphous structure, and had a very weak peak of V2O5 (002) owing to very thin films. However, the crystallite size of VOx films increased with increasing annealing temperature. The surface roughness of VOx films and average transmittance decreased with increasing annealing temperature. The resistivity of VOx films also decreased with increasing annealing temperature, while the electrical properties of films improved.
关键词： Transmittance,Unbalanced Magnetron Sputtering,Vanadium Oxide,Surface Roughness,Resistivity
更新于2025-09-23 15:23:52
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17.3: Black Photoresist Achieving Patterns with Extremely Low Reflection and Smooth Line Edge
摘要： This paper introduces a new type of black photoresist with a very low reflectance and very smooth pattern line edge that doesn't require adding micron-size particles. Combinations of poor solvent, good solvent, and selected special substances as solutes in the black photoresist can achieve matte surface during drying process. Because particles are not used to achieve matte surface, the line edge will be very smooth. This photoresist is likely appropriate for applications where light reflection or light scattering should be avoided, such as black matrix and smartphone camera surroundings.
关键词： black matrix,low reflective index,smart phone camera,matte surface,Black photoresist,line edge roughness
更新于2025-09-23 15:23:52
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Realizing Q> 300 000 in diamond microdisks for optomechanics via etch optimization
摘要： Nanophotonic structures in single–crystal diamond (SCD) that simultaneously con?ne and co-localize photons and phonons are highly desirable for applications in quantum information science and optomechanics. Here we describe an optimized process for etching SCD microdisk structures designed for optomechanics applications. This process allows the optical quality factor, Q, of these devices to be enhanced by a factor of 4 over previous demonstrations to Q ～ 335 000, which is suf?cient to enable sideband resolved coherent cavity optomechanical experiments. Through analysis of optical loss and backscattering rates, we ?nd that Q remains limited by surface imperfections. We also describe a technique for altering microdisk pedestal geometry which could enable reductions in mechanical dissipation.
关键词： surface roughness,optomechanics,quality factor,etch optimization,diamond microdisks
更新于2025-09-23 15:23:52
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Interferometric surface mapping of a spherical proof mass for ultra precise inertial reference sensors
摘要： In the context of our investigations on novel inertial reference sensors for space applications, we have explored a design utilizing an optical readout of a spherical proof mass. This concept enables full drag-free operations, hence reducing proof mass residual acceleration noise to a minimum. The main limitations of this sensor are errors in position determination of the center of mass of the proof mass due to the surface topography and the involved path length changes upon rotation. One solution is to apply a surface map for correction of the measurement data, thus improving the precision of position determination. This article presents the results of our one-dimensional interferometric surface topography measurements of a sphere, achieving uncertainties of ≈10 nm, as a first step to realize a complete surface map. The measurement setup consists of two heterodyne interferometers positioned in an opposing configuration, which measure the surface topography while the sphere is continuously rotated by a rotation stage.
关键词： figure,roughness,Surfaces,Roughness,Interferometry,Surface measurements
更新于2025-09-23 15:22:29
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Novel polyelectrolyte–Al2O3/SiO2 composite nanoabrasives for improved chemical mechanical polishing (CMP) of sapphire
摘要： A new type of polyelectrolyte–Al2O3/SiO2 composite nanoparticle with excellent dispersibility and superior polishing performance was successfully fabricated using a facile method. Silica acted as a bifunctional molecule by attaching to alumina via covalent bond and adsorbing polyelectrolytes by electrostatic interaction. The material removal rate of the polyelectrolyte–Al2O3/SiO2 abrasive was 30% higher than that of the pure Al2O3 abrasive. In addition, the sapphire surface was much smoother. The material removal mechanism was investigated during CMP using the microcontact and wear model. The enhanced removal rate was mainly attributed to the well-dispersed particles, which can accelerate mechanical removal process. The remarkably smooth surface was due to the decrease in penetration depth of the abrasive into the wafer. The results of this study provided a feasible strategy to satisfy the high efficiency and damage-free polishing requirements for sapphire planarization.
关键词： chemical mechanical polishing,composite abrasives,polyelectrolyte,surface roughness,sapphire,material removal rate
更新于2025-09-23 15:22:29