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- 2019
- polycrystalline ferrite-garnet
- magnetoplasmonic crystals
- magnetooptical effects
- deposition
- ion-beam methods
- sputtering
- plasmon resonance
- Physics
- Moscow Technological University
- Moscow State University
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Microstructures Manufactured in Diamond by Use of Laser Micromachining
摘要： Different microstructures were created on the surface of a polycrystalline diamond plate (obtained by microwave plasma-enhanced chemical vapor deposition—MW PECVD process) by use of a nanosecond pulsed DPSS (diode pumped solid state) laser with a 355 nm wavelength and a galvanometer scanning system. Different average powers (5 to 11 W), scanning speeds (50 to 400 mm/s) and scan line spacings (“hatch spacing”) (5 to 20 μm) were applied. The microstructures were then examined using scanning electron microscopy, confocal microscopy and Raman spectroscopy techniques. Microstructures exhibiting excellent geometry were obtained. The precise geometries of the microstructures, exhibiting good perpendicularity, deep channels and smooth surfaces show that the laser microprocessing can be applied in manufacturing diamond microfluidic devices. Raman spectra show small differences depending on the process parameters used. In some cases, the diamond band (at 1332 cm?1) after laser modification of material is only slightly wider and shifted, but with no additional peaks, indicating that the diamond is almost not changed after laser interaction. Some parameters did show that the modification of material had occurred and additional peaks in Raman spectra (typical for low-quality chemical vapor deposition CVD diamond) appeared, indicating the growing disorder of material or manufacturing of the new carbon phase.
关键词： laser microprocessing,polycrystalline diamond,microstructures
更新于2025-09-23 15:19:57
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Large-area grain-boundary-free copper films for plasmonics
摘要： Ultrasmooth single-crystalline metallic thin films provide several key advantages for the fabrication of well-defined and high-resolution plasmonic nanostructures, particularly complex integrated nanocircuits. For this purpose, copper is generally regarded as a poor plasmonic material compared to gold and silver because of its notorious oxidation issues when subjected to air exposure. Here, we report on the use of large-area grain-boundary-free copper films grown epitaxially on sapphire substrates in combination with focused ion beam milling to pattern plasmonic nanostructures with superior quality. The copper surfaces prepared using a single-crystalline copper sputtering target exhibit a very low roughness without any grain boundaries for varying film thicknesses and a strong resistance to oxidation, overcoming the bottleneck in conventional copper film fabrication. Surface plasmon resonance measurements show that improved dielectric constants with higher conductivity and long-term stability can be achieved using the single-crystalline copper films. Plasmonic nanohole arrays patterned from these high-quality films are found to display a stronger field enhancement compared to those made from polycrystalline copper films, thus resulting in an enhanced extraordinary optical transmission performance. This study suggests that our fabrication method is ideally suited for applications in copper-based plasmonic and nanophotonic devices as well as integrated nanocircuits on a large scale.
关键词： Single-crystalline films,Polycrystalline films,Surface plasmon resonances,Copper,Extraordinary optical transmission
更新于2025-09-23 15:19:57
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Experimental investigation on the machining characteristics of fixed-free abrasive combined wire sawing PV polycrystalline silicon solar cell
摘要： At present, the fixed abrasive wire sawing (FAWS) technology is gradually used in the photovoltaic industry to cut polycrystalline silicon slices. However, there are obvious directional wire marks, parallel grooves, and amorphous silicon layer on the surface of the slices formed by the FAWS, which leads to a high optic reflectivity of the textured surface obtained after the mature acid etching texturization technology. So the slices cannot meet the requirements of the photovoltaic cell. In the paper, a novel fixed-free abrasive combined wire sawing (FFACWS) technology for cutting PV polycrystalline silicon is presented to solve this problem, by adding loose SiC abrasives to cooling lubricant during the fixed abrasive wire sawing. A single-factor and orthogonal experimental study on sawing characteristics was carried out. The effect of size and mass fraction of SiC abrasives in the slurry, workpiece feed speed and wire speed on the surface morphology, roughness, and kerf loss were studied. The results show that within the range of the processing parameters in the paper studied, the obvious wire marks, parallel grooves, and ductile layers on the surface of the slices can be removed by the FFACWS. The surface roughness of the slices along the wire movement direction and the workpiece feed direction increases with the increase of the mass fraction of SiC abrasives in the slurry and workpiece feed speed and it decreases with the increase of wire speed. But the effect of the size of SiC abrasives is related to the matching of the protruding height of the fixed abrasives on the wire surface along the workpiece feed direction. In the wire movement direction, it increases with the size of SiC abrasives. The kerf loss increases with the increase of size and mass fraction of SiC abrasives in the slurry and the wire speed but has little effect with the change of workpiece feed speed.
关键词： Fixed-free abrasive combined wire sawing,Surface morphology,Surface roughness,Kerf loss,Photovoltaic polycrystalline silicon
更新于2025-09-23 15:19:57
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Investigation of polycrystalline Ga <sub/>x</sub> In <sub/>1a??a??a??x</sub> P for potential use as a solar cell absorber with tunable bandgap
摘要： There is ongoing interest in developing a stable, low-cost, 1.6–1.8 eV top-cell material that can be used for two-junction (tandem) solar cells, particularly in combination with a silicon bottom cell. In this work, polycrystalline GaInP is grown and characterized to explore its properties and use for this purpose. The film composition and deposition temperature are varied to determine their effects on grain size, morphology, and photoluminescence (PL) over a range of bandgaps from 1.35 to 1.7 eV. An Al-assisted post-deposition treatment for 1.7-eV polycrystalline GaInP results in a 90-fold increase in peak photoluminescence (PL) intensity, a 220-fold increase in integrated PL intensity, and increased time-resolved PL lifetime from <2 ns to 44 ns. The increase in PL intensity and lifetime is attributed to a reduction of nonradiative minority-carrier recombination at the top surface, and at grain boundaries near the surface, due to the formation of a higher-bandgap AlGaInP alloy. These materials provide a viable path toward increased minority-carrier concentration under illumination and improved recombination properties needed for high-efficiency tandem solar cells.
关键词： polycrystalline GaInP,tunable bandgap,post-deposition treatment,photoluminescence,solar cell
更新于2025-09-23 15:19:57
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Numerical study of microscale laser bulging based on crystal plasticity
摘要： Microscale laser bulging is an innovative and promising micro metal forming technology and is widely used in the micro electronics industry. With the image-based Voronoi tessellations, the three-dimensional finite element models of disk-shaped polycrystalline aggregates with different initial grain sizes were established to simulate the processes of microscale laser bulging of pure copper foil. The temporal-spatial-distributed laser shock wave pressure was employed to deform the polycrystalline aggregates of pure copper foil. A size-dependent unified constitutive model of crystal plasticity, incorporating the thermally-activated and viscous drag-dominated stages of dislocation motion, was developed and implemented into the finite element codes to describe the plastic deformation behavior at a wide range of strain rates. In the cases of different laser shock wave pressures and initial grain sizes, the predicted maximum bulging heights of pure copper foil are in good agreement with the experimental data, and the resultant thickness and surface roughness also correlate well with the corresponding experiment observations. The simulated equivalent plastic strains and Mises stresses of residual stress components were analyzed by the cross comparisons, and the effect of grain boundary on laser shock wave was further discussed in detail.
关键词： laser shock wave,numerical simulation,polycrystalline aggregates,crystal plasticity,microscale laser bulging
更新于2025-09-23 15:19:57
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Metallic indium segregation control of InN thin films grown on Si(1?0?0) by plasma-enhanced atomic layer deposition
摘要： InN thin films were grown on Si(1 0 0) substrates by plasma-enhanced atomic layer deposition (PEALD). In this work, It is found that the island growth of InN on Si(1 0 0) easily happens at the initial PEALD period. The PEALD parameters have been systematically investigated to optimize the size, density, coalescence and distribution uniformity of InN grains with good crystallinity and no metallic indium clustering. Especially, indium segregation of PEALD-grown InN has a direct dependence on the deposition temperature (T), the supply of tri-methylindium (TMIn) precursor and nitrogen plasma (NP) source. Based on our proposed PEALD mechanism of InN, a polycrystalline hexagonal InN thin film in the thickness of 24.2 nm has been well deposited at the growth per cycle (GPC) of 0.8 ?/cycle. And it shows a (0 0 2) preferential orientation and no any structural phase of metallic indium segregation. As a result, it may provide a useful guide for deeply understanding the PEALD growth mechanism of InN and In-rich nitrides, which further extends the promising applications in high-efficiency photovoltaics and high speed electronic devices.
关键词： Indium segregation,PEALD,Growth mechanism,InN,Polycrystalline
更新于2025-09-23 15:19:57
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Phase-field modeling of domain evolution in ferroelectric materials in the presence of defects
摘要： The properties of ferroelectric devices are strongly influenced, besides crystallographic features, by defects in the material. To study this effect, a fully coupled electromechanical phase-field model for 2D ferroelectric volume elements has been developed and implemented in a Finite Element code. Different kinds of defects were considered: holes, point charges and polarization pinning in single crystals, as well as grain boundaries in polycrystals, without and with additional dielectric interphase. The impact of the various types of defects on the domain configuration and the overall coercive field strength is discussed in detail. It can be seen that defects lead to nucleation of new domains. Compared to the energy barrier for switching in an ideal single crystal, the overall coercive field strength is significantly reduced towards realistic values as they are found in ferroelectric devices. Also the simulated hysteresis loops show a more realistic shape in the presence of defects.
关键词： polycrystalline ferroelectric,phase-field modeling,microstructural defects
更新于2025-09-19 17:15:36
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Sputtered indium tin oxide as a recombination layer formed on the tunnel oxide/poly-Si passivating contact enabling the potential of efficient monolithic perovskite/Si tandem solar cells
摘要： We focus on utilizing sputtered indium tin oxide (ITO) as a recombination layer, having low junction damage to an n-type silicon solar cell with a front-side tunnel oxide passivating electron contact, thereby enabling the development of a high efficiency monolithic perovskite/Si tandem device. High transparency and low resistivity ITO films are deposited via low power DC magnetron sputtering at room temperature onto a front-side thin SiOx/n+ poly-Si contact in a complete Cz n-Si cell with a back-side Al2O3/SiNx passivating boron-diffused p+ emitter on a random pyramid textured surface. We report the cell characteristics before and after ITO sputtering, and we find a cure at 250 °C in air is highly effective at mitigating any sputtering induced damage. Our ITO coated sample resulted in an implied open-circuit voltage (iVoc) of 684.7 ± 11.3 mV with the total saturation current density of 49.2 ± 14.8 fA/cm2, an implied fill factor (iFF) of 81.9 ± 0.8%, and a contact resistivity in the range of 60 mΩ-cm2 to 90 mΩ-cm2. After formation of a local Ag contact to the rear emitter and sputtered ITO film as the front-side contact without grid fingers, the pseudo-efficiency of 20.2 ± 0.5% was obtained with the Voc of 670.4 ± 7 mV and pseudo FF of 77.3 ± 1.3% under simulated one sun with the calculated short-circuit current density of 30.9 mA/cm2 from the measured external quantum efficiency. Our modelling result shows that efficiency exceeding 25% under one sun is practically achievable in perovskite/Si tandem configuration using the ITO recombination layer connecting a perovskite top cell and a poly-Si bottom cell.
关键词： Tandem solar cell,Transparent conductive oxide,Polycrystalline silicon,Passivating contacts,Perovskite,TOPCon
更新于2025-09-19 17:13:59
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A multiscale materials-to-systems modeling of polycrystalline PbSe photodetectors
摘要： We present a physics based multiscale materials-to-systems model for polycrystalline PbSe photodetectors that connects fundamental material properties to circuit level performance metrics. From experimentally observed ?lm structures and electrical characterization, we ?rst develop a band structure model that explains carrier-type inversion and large carrier lifetimes in sensitized ?lms. The unique band structure of the photosensitive ?lm causes separation of generated carriers with holes migrating to the inverted PbSejPbI2 interface, while electrons are trapped in the bulk of the ?lm intergrain regions. These ?ows together form the 2-current theory of photoconduction that quantitatively captures the I(cid:2)V relationship in these ?lms. To capture the e?ect of pixel scaling and trapped carrier blocking, we develop a model for the metallic contacts with the detector ?lms based on the relative workfunction di?erences. We also develop detailed models for various physical parameters such as mobility, lifetime, quantum e?ciency, noise, etc. that connect the detector performance metrics such as responsivity R and speci?c detectivity D* intimately with material properties and operating conditions. A compact Verilog-A based SPICE model is developed which can be directly combined with advanced digital Read-Out Integrated Circuit cell designs to simulate and optimize high performance Focal Plane Arrays which form a critical component in the rapidly expanding market of self-driven automotive, internet of things security, and embedded applications.
关键词： polycrystalline materials,PbSe photodetectors,carrier-type inversion,multiscale modeling,quantum efficiency,band structure,SPICE model
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Growth Evolution of Polycrystalline CdTe/CdS with Atomic Scale Resolution via Molecular Dynamics
摘要： A new method to study polycrystalline growth of CdTe layers has been developed using Molecular Dynamics (MD). The results show the creation of polycrystalline CdTe/CdS structures that closely recreate the morphology of experimental polycrystalline growth. The growth shows the nucleation and coalescence of grains at early stages for CdS on amorphous CdS and CdTe on polycrystalline CdS.
关键词： grain boundaries,grain growth evolution,polycrystalline structures,molecular dynamics
更新于2025-09-19 17:13:59