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Effect of stacking faults and surface roughness on the thermal conductivity of InAs nanowires
摘要： Low thermal conductivity and high power factor are desirable for thermoelectric materials. These properties can be achieved by patterning devices into nano-structures such as nanowires (NWs). The thermal conductivity can be further reduced by altering the NW geometry through the introduction of surface roughness (SR) or stacking faults (SFs). In this paper, relaxation times for scattering of phonons at SFs and SR are developed to accurately compute the impact of both effects on the thermal conductivity of InAs NWs with different diameters. It is found that similar reductions of the thermal conductivity can be obtained with SFs instead of SR. For the shortest possible distance between SFs along a NW, the room temperature thermal conductivity can be reduced to 25% compared to an ideal NW. For a NW with rough surface, a more than 80% decrease of the thermal conductivity is possible for specific roughness profiles. All available experimental data on the lattice thermal conductivity of InAs NWs confirm the theoretical models and simulation results.
关键词： surface roughness,thermal conductivity,phonon scattering,stacking faults,InAs nanowires
更新于2025-09-10 09:29:36
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Cathode plasma electrolytic deposition of Al2O3 coatings doped with SiC particles
摘要： Semiconductor particles doped Al2O3 coatings were prepared by cathode plasma electrolytic deposition in Al(NO3)3 electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7 μm and 40 nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5 g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5 g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings.
关键词： Cathode plasma electrolytic deposition,Surface roughness,Al2O3 coatings,SiC particles
更新于2025-09-10 09:29:36
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The investigation of the diameter dimension effect on the Si nano-tube transistors
摘要： The vertical gate-all-around (V-GAA) Si nano-tube (NT) devices with different diameter dimensions are studied in this work with the promising device performance. The V-GAA structure makes the transistor easy to be scaled down continuously to meet the complementary metal-oxide-semiconductor (CMOS) scaling requirements of the 7/10 nm technology node and beyond. The Si NT device with the hollow structure is demonstrated to have the capability to “deplete” and “screen-out” the out-of gate control carriers in the center of the NT and further result in the better device short channel control. Based on the study in this work, the V-GAA Si NT device with the optimized diameter dimension (= 20 nm) can benefit the Ion-state current and reduce the Ioff-state stand-by power simultaneously, due to the less surface roughness scattering and the better short channel control characteristics. The proposed V-GAA Si NT device is regarded as one of the most promising candidates for the future application of the sub-7/10 nm logic era.
关键词： diameter dimension effect,Si nano-tube transistors,short channel control,surface roughness scattering,vertical gate-all-around
更新于2025-09-10 09:29:36
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Optical vortex phase determination for nanoscale imaging
摘要： In this research we develop a principle of optical vortex phase analysis and its application to surface imaging with high accuracy measurements in nanoscale range. Two-coordinate scanning of the sample allow to retrieve an information about shape and roughness for optically transparent and reflecting surfaces exceeding optical diffraction limit. The interference between singular beam and reference wave, in general, carrying optical vortex with single or doubled topological charge allow to extract the data about phase delay caused by surface features or refraction. This method is also applicable for non-destructive testing of biological structures and live cells in real-time regime. Automatic processing of vortex interferograms allow to achieve a vertical and longitudinal resolution down to 1,75 nm and 7 nm respectively for visible light sources.
关键词： biological structures,nanoscale imaging,surface roughness,non-destructive testing,optical vortex phase analysis
更新于2025-09-09 09:28:46
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On-machine texturing of PCD micro-tools for dry micro-slot grinding of BK7 glass
摘要： While using diamond micro-tools for micro-grinding, tool re-clamping errors and low chip removal space from machining zone are the primary factors which cause large vibrations, higher grinding forces and poor surface quality. On-machine tool preparation and tool texturing prior to micro-grinding can reduce tool re-clamping error. It can further help to reduce the tool-workpiece contact area along with enhanced chip removal from the machining zone speci?cally essential during dry micro-grinding as usage of the cutting ?uid should be minimized or completely avoided for environmental aspects. In this study, end faces of polycrystalline diamond (PCD) micro-tools have been on-machine textured using micro electro-discharge machining (micro-EDM) process. Four types of textured tools are envisaged viz. tool with one micro-cavity at the center of the end face (T2), one micro-groove along the end face diameter (T3), two intersecting micro-grooves at the end face (T4) and four intersecting micro-grooves at the end face (T5). A new term “contact area ratio” is de?ned to explain the texture dimension on the end face of the micro-grinding tools. Performances of di?erent micro-textured tools (T2, T3, T4 and T5) with respect to a normal commercial tool (T1) in terms of grinding force, surface roughness and micro-slot quality are investigated for micro-slot grinding of BK7 glass. It is observed that micro-textured micro-grinding tool e?ciently serves the purpose of provisional chip collection in passive grinding areas of the tool whereas chip adhesion or wear on the active grinding areas signi?cantly gets reduced as compared to un-textured tools. Maximum reductions in the x and y direction forces are observed with tool type T5 compared to all other tool types. Reduction in z direction force is comparable for both tool types T2 and T3. Average surface roughness decreased from tool type T1 to type T2, T3 and up to tool type T4 whereas it again increased for tool type T5. The current study shows that textured micro-grinding tools are capable of reducing high normal forces, surface roughness and material dragging which are major concerns during micro-grinding with ?at-end poly-crystalline diamond tools.
关键词： Polycrystalline diamond tool,Micro-texture,Micro-grinding,BK7 glass,Surface roughness,Grinding force,Micro-EDM
更新于2025-09-09 09:28:46
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Effects of inclination angle on surface roughness and corrosion properties of selective laser melted 316L stainless steel
摘要： Balling effect is an inevitable defect during Selective laser melting (SLM) process, and it deteriorates the mechanical and corrosion properties of the resulting parts. In this work, the SLM process is used with various inclination angles to fabricate samples. The deep relationship between the selective laser melting process and the corrosion properties of the as-SLM fabricated parts is established to understand the effect of the inclination angle on the surface roughness, microstructure evolution, and corrosion properties of 316L stainless steel components. Results show that the Ra value of fabricated parts increased with increasing inclination angles. Inclination angles play an important role in balling and defect formation. Fabricated parts exhibit a wide passive region in salty environments. The corrosion resistance of the SLM samples after polishing is decreased comparing to that of the unpolished which attribute to porosity and balling behavior. The typical corrosion characterization of polished surface is pitting and localized corrosion, and it mainly origin of pores and balling. Meanwhile, balling behavior accelerated corrosion rates of non-polished parts.
关键词： Selective laser melting,Inclination angles,Surface roughness,Corrosion resistant
更新于2025-09-09 09:28:46
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Plasma Impact on PI Roughness
摘要： The standard pillar bump structure [1-3] is shown in Figure 2. Polyimide Re-passivation (PI) layer is widely used for pillar bump structure due to the increasingly stringent reliability requirements [4-5]. PI layer serves as stress buffer layer which can enhance the structure reliability performance. And PI will be the direct surface contact material to FCBGA molding compound, so the PI surface roughness is a key factor to the adhesion between PI and molding compound. Lower surface roughness will cause delamination between PI and molding compound while higher surface roughness may cause flip chip process issue like back-grinding tape residue due to higher adhesion between PI and back-grinding tape [6-7]. During the pillar bump process, the PI surface roughness is influenced by many plasma steps like gas and so on. In the present paper, plasma process parameters such as gas, process power and process time are studied in order to get the correlation between these process parameters and PI surface roughness result. This correlation can be used to further study the surface roughness with the assembly site required at the assembly process. As depicted in Figure 3, there are distinctions in the diffraction values of Selected Area Diffraction Pattern (SADP) in different process steps (PI Curing, O2 Descum, RF, Etch, Ar Descum). The influence of different gases plasma on PI surface roughness is quite significant, among which O2 plasma has more significant impact than others, which provides guidance for further research of PI surface roughness in FCBGA
关键词： PI surface roughness,Plasma,PI layer,Adhesion
更新于2025-09-09 09:28:46
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Experimental study on surface generation in optical glass with fluid jet polishing process
摘要： Fluid jet polishing process is an inexpensive technique and capable to produce ultra-smooth surface. In fluid jet polishing process, the surface generation mainly depends upon the size and type of the abrasive particle, the jet pressure, the exposure time, the impact angle, etc. In this work, experimental investigation were carried out to study the influence of different slurry exposure time on surface roughness of optical glass with varying jet pressure, particle diameter and type of particle at 30o impact angle. The surface roughness measurement and surface morphology characterisation were done to understand the surface changes.
关键词： particle size,jet pressure,exposure time,abrasives,surface roughness
更新于2025-09-09 09:28:46
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Interferometric Angular Decorrelation Analysis of 1-D Rough Surface With Pencil Beam Incidence
摘要： Interferometric synthetic aperture radar (InSAR) uses phase difference of radar echoes, either from multiple passes along the same trajectory or from multiple displaced phase centers on a single pass, to generate interferogram. Scattering correlation in the angular dimension is a critical factor determining the quality of InSAR interferogram. It can be modeled with the angular correlation function (ACF). In this letter, the ACF of a 1-D rough surface under incidence of a tapered wave, namely, a pencil beam, is studied numerically for correlation analysis of InSAR. An analytic ACF is ?rst derived based on the ?rst-order small perturbation method. It is then validated statistically by the method of moment of electromagnetic scattering. Analysis of the ACF simulations indicate that the ACF of backscattering from a randomly rough surface exhibits a shape of sinc function, which depends on tapering parameter g, interferometric incidence angles θ1 and θ2. Several numerical simulations of different rough surface spectrums demonstrate that the analytical ACF ?ts well with numerical results as long as g is the larger several correlation lengths l.
关键词： interferometric synthetic aperture radar (InSAR),Angular correlation function (ACF),small perturbation method (SPM),surface roughness
更新于2025-09-09 09:28:46
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Materials Science and Technology of Optical Fabrication || Surface Roughness
摘要： Because it influences optical-scatter losses and downstream laser modulation [1], the surface roughness of an optical-glass component is an important parameter for many optical systems (including lasers and telescopes). During optical polishing, a number of interactions between the workpiece, polishing slurry, and pad may influence the resulting workpiece roughness at different spatial scale lengths. The phenomena affecting large spatial scale length (>1 mm) on the workpiece (i.e. surface figure) are described in Chapter 2 (see Figure 2.1). By contrast, in this chapter, the phenomena and process parameters affecting short spatial scale lengths (<1 mm) (i.e., surface roughness from AFM2 scale roughness to μ-roughness) are described (see Figure 1.8). Fine-scale roughness, typically measured by atomic force microscopy (AFM), is referred to as AFM1 (≤5 μm) and AFM2 roughness (≤50 μm), as represented on the right of the plot. Roughness at this scale is influenced by parameters such as the single-particle removal function, Beilby layer properties, slurry particle size distribution (PSD), pad topography, pad mechanical properties, and slurry particle redeposition. The next higher spatial scale length (the micrometer to millimeter range, known as micro- or μ-roughness), is usually measured by white-light interferometry (Figure 1.8). μ-Roughness is affected not only by the smaller spatial-scale length phenomena given above, but also by factors governing slurry-interface interactions, such as the spatial distribution of slurry particles present at the interface. These parameters and phenomena are listed Figure 4.1, consisting of a schematic of the workpiece–lap interface at the spatial scale length of interest that influences the final polished surface roughness. Figure 4.1 provides a valuable outline for this chapter.
关键词： Optical Polishing,Slurry PSD,Pad Topography,AFM,μ-Roughness,Surface Roughness
更新于2025-09-04 15:30:14