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Optimization of Boron Spin on Dopant (BSoD) Diffusion for Emitter Formation in n-type c-Si Solar Cells
摘要： Boron spin on dopant (BSoD) is an alternative boron source to BBr3 liquid dopant for p+ emitter formation in n-type solar cells. In this work, we have used different process control steps to lower the BSoD diffusion issues to have a uniform sheet resistance of p+ emitters. After eliminating the boron (B) precipitates formed during the process of diffusion by control process steps, the emitters have been optimized for sheet resistance values ≤60?/□ with variation less than ±5?/□. The corresponding junction depth is less than 800nm as measured by SIMS analysis. All the experiments are carried out with Czochralski n-type c-Si wafers which showed an improvement of effective minority carrier lifetimes by more than 2 times in controlled process steps. The measured Sun’s Voc and implied Voc are in the range 575- 600mV without any passivation. The PC1D simulation shows the efficiency of the solar cell without any passivation is 14.8%. This indicates the BSoD as a promising source for the p+ emitter formation in n- type c-Si solar cells.
关键词： boron rich layer,Sheet resistance,boron spin on dopant,PC1D simulation
更新于2025-09-16 10:30:52
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Isotopic Analysis and Characterization of Boric Acid Diffused Emitters in n-type c-Si Solar Cells
摘要： Boric acid (BA) is one of the boron dopant sources used in recent years to fabricate emitters for n-type c- Si solar cells. Boric acid solution with concentrations less than 4% is sufficient enough to get doping concentrations with sheet resistance values 10 ?/sq to 90 ?/sq under different diffusion conditions. Isotopic analysis of BA diffused emitter, optimized for different sheet resistances have been studied in this work. Cs ions of 1KV 300x300 raster ions have been used for the emitters and it has resulted detection of 11B and 28Si isotopes in all the boron diffused samples. Isotopic analysis of borosilicate glass (BSG) and boron rich layer (BRL), corresponding to different dopant concentrations, also shows isotope detections and they vary according to natural abundance.
关键词： isotopic analysis,boron rich layer,sheet resistance values
更新于2025-09-12 10:27:22
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Investigation of interactions between ultrafast laser beams and screen-printed silver nanopaste films
摘要： This study aims to investigate the interaction between ultrafast laser beams and screen-printed silver (Ag) nanopaste ?lms for strain sensors. After single pulse ablation of Ag nanopaste ?lms with a thickness of 4.58 μm, the ablation threshold was approximately 0.2 J/cm2. By increasing single pulse laser ?uences from 0.78 J/cm2 to 1.87 J/cm2, the laser-ablated line widths and depths of Ag nanopaste ?lms were ranging from 22 ± 0.1 μm and 4 ± 0.09 μm to 44.8 ± 1.4 μm and 4.2 ± 0.05 μm, respectively. The sheet resistance of laser-processed Ag nanopaste ?lms was measured by a four-point probe instrument. When the single pulse laser ?uences set from 4.7 mJ/cm2 to 1.97 J/cm2, the measured sheet resistances near the laser-ablated line edge of 0.5 mm were 59.52 ± 0.76 mΩ/sq and 115.83 ± 6.11 mΩ/sq, respectively. The optimal ultrafast laser processing parameters consisting of the areal laser ?uence of 47.4 J/cm2, the laser pulse repetition rate of 300 kHz, the scanning speed of galvanometers of 500 mm/s, and the overlapping rate of laser spots of 96.1% were used to pattern strain sensors with transversal and longitudinal electrode structures on Ag ?lm/glass substrates.
关键词： Sheet resistance,Silver (Ag) nanopaste ?lms,Single pulse ablation,Strain sensor,Ultrafast laser
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Accurate contact and contactless methods for emitter sheet resistance testing of PV wafers
摘要： The emitter sheet resistance Rs e on textured silicon wafers is measured by four-point-probe (4PP), eddy-current, and junction-photovoltage (JPV) techniques. In the sample set – manufactured for this study – Rs e of diffused n++ and p++ layers and the bulk resistivity ρ of the substrate wafers are all varied to cover the entire range of today’s silicon PV production. It was found, that the 4PP results – from the widely used 4PP sensor with sharp and hard tips – are strongly influenced by the bulk resistivity of the substrate wafers and show poor correlation to the readings of the contactless techniques. In addition, 4PP probes with different tip parameters provide different Rs e values. A simple model is proposed to explain the influence of ρ to the measured Rs e. This new understanding led to the application of a simple design “soft contact” 4PP sensor, which provides a bulk resistivity independent determination of Rs e. Results from the soft-contact 4PP sensor are in excellent agreement with Rs e calculated from the eddy-current method. This agreement confirms the accuracy of the soft-probe 4pp technique. Knowing the precise Rs e values of all wafers enabled the optimization of the measurement parameters of the recently developed contactless, differential JPV sensor, which is already used in PV production lines. After optimization, the differential JPV measurement was proven to be very precise for the entire sample parameter range.
关键词： four-point-probe,junction-photovoltage,emitter sheet resistance,eddy-current,PV wafers
更新于2025-09-11 14:15:04
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[IEEE 2018 2nd IEEE International Conference on Power Electronics, Intelligent Control and Energy Systems (ICPEICES) - Delhi, India (2018.10.22-2018.10.24)] 2018 2nd IEEE International Conference on Power Electronics, Intelligent Control and Energy Systems (ICPEICES) - Development of a Characterization Tool for Determination of Sheet Resistance at 9 Places of Large Area 156 mm by 156 mm Diffused Silicon Wafer in Less than 5 Seconds and Its Application in Making High Efficiency Silicon Solar Cells
摘要： Sheet resistance measurement using 4 probe method is a very well established technique for measuring the sheet resistance of a thin film on a substrate. This technique is widely used to measure the sheet resistance of diffused silicon wafer in solar photovoltaic industry. However with respect to solar cell industry, the drawback associated with this technique is, it measures the sheet resistance of a very small area. For a large area silicon wafer of size 156 mm by 156 mm, a four probe sheet resistance measurement instrument will take several minutes to take readings at several places on the entire area of the wafer. In the present work a solar cell characterization tool is developed for measuring the sheet resistance at 9 places on a diffused silicon wafer using 9 four probe heads mounted on a single plate. The characterization tool developed in the present work can tell the uniformity of diffusion in a diffused silicon wafer within few seconds on the screen of a computer monitor. Continuous data logging helps in characterizing wafers which are >50,000/day in any smallest PV industry.
关键词： Sheet Resistance,crystalline silicon solar cell,Four probe technique,Shallow emitter
更新于2025-09-11 14:15:04
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Characteristics of Graphene Oxide Films Reduced by Using an Atmospheric Plasma System
摘要： The chemical oxidation method can be used to mass-produce graphene oxides (GOs) from highly oriented pyrolytic graphite. However, numerous oxygen-containing functional groups (hydroxyl, epoxy, carbonyl, etc.) exist in typical GO surfaces, resulting in serious electrical losses. Hence, GO must be processed into reduced graphene oxide (rGO) by the removal of most of the oxygen-containing functional groups. This research concentrates on the reduction efficiency of GO films that are manufactured using atmospheric-pressure and continuous plasma irradiation. Before and after sessions of plasma irradiation with various irradiation times, shelters, and working distances, the surface, physical, and electrical characteristics of homemade GO and rGO films are measured and analyzed. Experimental results showed that the sheet resistance values of rGO films with silicon or quartz shelters were markedly lower than those of GO films because the rGO films were mostly deprived of oxygen-containing functional groups. The lowest sheet resistance value and the largest carbon-to-oxygen ratio of typical rGO films were approximately 90 ?/sq and 1.522, respectively. The intensity of the C–O bond peak in typical rGO films was significantly lower than that in GO films. Moreover, the intensity of the C–C bond peak in typical rGO films was considerably higher than that in GO films.
关键词： sheet resistance,oxygen functional group,GO and rGO films,plasma irradiation,carbon-to-oxygen ratio
更新于2025-09-04 15:30:14
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High-Performance PEDOT:PSS/Hexamethylene Diisocyanate-Functionalized Graphene Oxide Nanocomposites: Preparation and Properties
摘要： Graphene oxide (GO) has emerged as an ideal ?ller to reinforce polymeric matrices owing to its large speci?c surface area, transparency, ?exibility, and very high mechanical strength. Nonetheless, functionalization is required to improve its solubility in common solvents and expand its practical uses. In this work, hexamethylene diisocyanate (HDI)-functionalized GO (HDI-GO) has been used as ?ller of a conductive polymer matrix, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The nanocomposites have been prepared via a simple solution casting method, and have been characterized by scanning electron microscopy (SEM), UV–Vis and Raman spectroscopies, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile tests, and four-point probe measurements to get information about how the HDI-GO functionalization degree (FD) and the HDI-GO concentration in the nanocomposite in?uence the ?nal properties. SEM analysis showed a very homogenous dispersion of the HDI-GO nanosheets with the highest FD within the matrix, and the Raman spectra revealed the existence of very strong HDI-GO-PEDOT:PSS interactions. A gradual improvement in thermal stability was found with increasing HDI-GO concentration, with only a small loss in transparency. A reduction in the sheet resistance of PEDOT:PSS was found at low HDI-GO contents, whilst increasing moderately at the highest loading tested. The nanocomposites showed a good combination of stiffness, strength, ductility, and toughness. The optimum balance of properties was attained for samples incorporating 2 and 5 wt % HDI-GO with the highest FD. These solution-processed nanocomposites show considerably improved performance compared to conventional PEDOT:PSS nanocomposites ?lled with raw GO, and are highly suitable for applications in various ?elds, including ?exible electronics, thermoelectric devices, and solar energy applications.
关键词： hexamethylene diisocyanate,PEDOT:PSS,functionalization degree,nanocomposite,optical transmittance,sheet resistance,graphene oxide,mechanical properties
更新于2025-09-04 15:30:14