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The effect of cut depth and distribution for abrasives on wafer surface morphology in diamond wire sawing of PV polycrystalline silicon
摘要： Due to the existence of an acid etch resistant thin amorphous silicon layer over the smooth grooves of the diamond wire sawing polycrystalline silicon wafer surface, the anti-re?ection e?ect is usually not ideal using the mature acidic texturization. The amorphous silicon layer will be produced on the machined surface by material ductile removal. Therefore, during the process of cutting photovoltaic polycrystalline silicon wafers, the material removed in the brittle way is expected and the surface topography of the wafers formed with the brittle fracture is better for the texture fabricating. In this paper, a mathematical model considering the in?uences of process parameters and wire saw parameters was developed based on indentation fracture mechanics. The variations of cutting groove pro?le formed by di?erent material removal modes were also included. The e?ect of abrasives distributed on the wire saw on material removal and surface formation of polysilicon was analyzed. The results showed that most of abrasives removed material with ductile removal mode, however, the volume of the material removed by abrasive in ductile mode is less than 10% of the total removal volume. Brittle fracture removal mode was still the major way of material removal in diamond wire sawing. With the same ratio of the feed rate and wire speed, the faster feed rate and wire speed will not only improve the cutting e?ciency, but also is easier to obtain a brittle fracture surface. There is a critical angle θc for the distribution of abrasives on the wire saw surface. Only when the position angle of the abrasive removing material in brittle mode is less than θc, the brittle fracture can be formed on the wafers surface.
关键词： Diamond wire sawing,Depth of cut,Material removal mode,Photovoltaic polycrystalline silicon
更新于2025-09-23 15:23:52
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Investigation of hydrogen effect on phosphorus-doped polysilicon thin films
摘要： Polycrystalline silicon is widely used in microelectronic and photovoltaic applications. The main problem of this material is the recombination of charge carriers at the grain boundaries which affects the efficiency of the polycrystalline silicon solar cells. In order to improve the crystalline quality and the electrical properties of phosphorus-doped poly-silicon thin films, heat treatments under hydrogen were carried out. This allowed the occupation of the dangling bonds at the grain boundaries and made them inactive, which resulted in improved optoelectronic properties of the treated samples. It has been shown that the effect of hydrogen on the electrical characteristics is more pronounced for low doping concentrations where a 20% improvement of the free carrier concentration was obtained. In addition, the results have shown that the introduction of hydrogen in poly-silicon thin films reduces the density of trap states at the grain boundaries.
关键词： hydrogen,passivation,solar cells,grain boundaries,Polycrystalline silicon
更新于2025-09-23 15:21:21
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The impacts of LPCVD wrap-around on the performance of n-type tunnel oxide passivated contact c-Si solar cell
摘要： In this paper, Tunnel Oxide Passivated Contact (TOPCon) silicon solar cells with the industrial area (244.32cm2) are fabricated on N-type silicon substrates. Both the ultra-thin tunnel oxide layer and phosphorus doped polycrystalline silicon (polysilicon) thin film are prepared by the LPCVD system. The wrap-around of polysilicon is observed on the surface of borosilicate glass (BSG). The polysilicon wrap-around can form a leakage current path, thus degrades the shunt resistance of solar cells, and leads to the degradation of solar cell efficiency. Different methods are adopted to treat the polysilicon wrap-around and improve shunt resistance of solar cells. The experimental results indicate that a chemical etching method can effectively solve the problem of polysilicon wrap-around and improve the performance of solar cells. Finally, a conversion efficiency of 22.81% has been achieved by our bifacial TOPCon solar cells, with Voc of 702.6 mV, Jsc of 39.78 mA/cm2 and FF of 81.62 %.
关键词： LPCVD,wrap-around,Tunnel oxide passivated contact,polycrystalline silicon thin film
更新于2025-09-23 15:21:01
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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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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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Recycling of silicon scraps by directional solidification coupled with alternating electromagnetic field and its electrical property
摘要： In this paper, alternating electromagnetic field and directional solidification are used to separate SiC and Si3N4 in polycrystalline silicon tailings. It is found the inclusion particles move downward at the center of the ingot and moving upward at the edge of the ingot by a variety of forces during the directional solidification process. The electromagnetic force accelerates the melt flow and enhances the lift force, so that larger particles can be pushed to the top of the ingot. Rod-shaped Si3N4 and block-shaped SiC particles show symbiotic relationship between each other. The aggregation of inclusion particles adsorbs metallic impurities, especially volatile metals, due to the effects of mushy region and short-circuit diffusion. The average conversion efficiency of the solar cells (Al-BSF method) prepared using the recycled silicon reached 18.56%, which meets the demand of the solar cells.
关键词： SiC,Alternating magnetic field,Directional solidification,Si3N4,Polycrystalline silicon
更新于2025-09-19 17:13:59
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Ultraviolet Nanosecond Laser Annealing for Low Temperature 3D-Sequential Integration Gate Stack
摘要： For the top tier in a 3D sequential integration, we propose a low temperature gate first approach in which an in-situ doped amorphous silicon layer is deposited at 475°C then subsequently converted into a polycrystalline film using ultraviolet nanosecond laser annealing. We demonstrate the ability to obtain a low resistance poly-Si gate for the top transistors within a thermal budget expected to preserve the bottom devices electrical performance.
关键词： Ultraviolet Nanosecond Laser Annealing,Polycrystalline Silicon,3D-Sequential Integration,Low Temperature Gate Stack
更新于2025-09-16 10:30:52
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Pixel Circuit With Leakage Prevention Scheme for Low-Frame-Rate AMOLED Displays
摘要： This work proposes a new pixel circuit for active-matrix organic light-emitting (AMOLED) smartwatch displays with a low frame rate. Within the long emission period, the leakage current of a low-temperature polycrystalline silicon thin-film transistor (LTPS TFT) is reduced to suppress the distortion of the driving voltage at the gate node of the driving TFT. Based on the measured electrical characteristics of a fabricated p-type LTPS TFT, the HSPICE model is established to verify the feasibility of the proposed circuit. The analytical results indicate that the relative OLED current error rates are all below 4.73%, as the threshold voltage of TFT varies by ±0.5 V. Notably, the OLED current varies by only 2.94% during the emission period of 66.7 ms at a medium gray level, demonstrating the effectiveness of the leakage prevention scheme.
关键词： low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs),Active-matrix organic light-emitting diode (AMOLED),leakage current prevention
更新于2025-09-16 10:30:52
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Comprehensive analysis of blue diode laser-annealing of amorphous silicon films
摘要： The low temperature polycrystalline silicon (LTPS) method has proved to be a technical breakthrough, accomplishing semiconductor thin films with remarkable mobility for a range of high-performance displays, including liquid crystal display and organic light emitting diodes. However, utilizing a conventional excimer laser source for LTPS incurs high cost. In this paper, we demonstrate a comprehensive analysis of the crystallization mechanism of a-Si film (94 nm) and the thermal deformation of the glass substrate induced by Blue diode Laser Annealing (BLA). BLA provides high quality laterally grown crystals over 4 μm × 10 μm on glass substrates, which were examined by optical microscopy, scanning electron microscopy, and Raman spectroscopy. In addition, the permanent deformation introduced by the annealing process is numerically modeled, instantiating how to control the heat conduction from the thin film that affects the substrate. Our findings reveal that the permanent thermal deformation depth that can be obtained is comparable to the roughness of the silicon film for the optimum scanning speed and laser power. The combination of both experimental and numerical results elucidates the manifested physical mechanisms during the BLA process and provides the guidelines to improve the experimental parameters of this process.
关键词： Lateral grain growth,Glass deformation,Silicon thin film,Low Temperature Polycrystalline Silicon (LTPS),Blue diode laser
更新于2025-09-12 10:27:22
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Preparation of novel lead-free Ag-doped glass frit for polycrystalline silicon solar cells by sol-gel method
摘要： A novel Ag-doped glass frit is prepared by the sol-gel method. Nitrogen adsorption-desorption isotherms indicate that the frit has a large BET surface area and a small particle size which promotes front contact metallization. When the glass frit is used for the front contact electrode of polycrystalline silicon solar cells (pc-Si solar cells), it exhibits excellent wettability and etching results on the SiNx layer and the Si substrate. The pc-Si solar cells with the as-prepared frit has a better photoelectric conversion efficiency (18.2%) and is 0.8% higher than the solar cells using the conventional frit, which is due to the frit will produce a lot of Ag nanocrystals at the interface of the glass layer, promoting the formation of excellent ohmic contact between the Ag electrode and n-Si layer, and reducing the contact resistance of solar cells.
关键词： Ag-doped glass frit,polycrystalline silicon solar cells,photoelectric conversion efficiency,sol-gel method
更新于2025-09-12 10:27:22