18 research outputs found

    Crack origin and detection in thin cristallyne solar cells in a production line

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    In order to reduce cost and make up for the rising price of silicon, silicon wafers are sliced thinner and wider,eading to weaker wafers and increased breakage rates during fabrication process. In this work we have analysed different cracks origins and their effect on wafer’s mechanical strength. To enhance wafer’s strength some etching methods have been tested. Also, we have analysed wafers from different points of an entire standard production process. Mechanical strength of the wafers has been obtained via the four line bending test and detection of cracks has been tested with Resonance Ultrasonic Vibration (RUV) system, developed by the University of South Florida

    Method of detecting and monitoring stresses in a semiconductor wafer

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    A method of detecting and monitoring elastic strains in a semiconductor wafer (12) comprising the steps of coupling the wafer (12) to a transducer (10) having a periphery (11). This is followed by operating the transducer (10) to produce ultrasonic vibrations at a predetermined wavelength λ and propagating a standing wave through the wafer (12) in response to the ultrasonic vibrations. The method is characterized by extending the wafer (12) in a cantilevered section L from the periphery (11) of the transducer (10) to a distal end (13), and measuring the amplitude of the standing wave λ in the cantilevered section L. For maximum efficiency, the cantilevered section L is substantially one quarter of the predetermined wavelength (λ/4)

    In-Line Crack and Stress Detection in Silicon Solar Cells Using Resonance Ultrasonic Vibrations

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    Statement of Problem and Objectives. Wafer breakage in automated solar cell production lines is identified as a major technical problem and a barrier for further cost reduction of silicon solar module manufacturing. To the best of our knowledge, there are no commercial systems addressing critical needs for in-line inspection of the mechanical quality of solar wafers and cells. The principal objective of the SBIR program is to validate through experiments and computer modeling the applicability of the Resonance Ultrasonic Vibrations system, which ultimately can be used as a real-time in-line manufacturing quality control tool for fast detection of mechanically unstable silicon solar cells caused by cracks. The specific objective of Phase II is to move the technology of in-line crack detection from the laboratory level to commercial demonstration through development of a system prototype. The fragility of silicon wafers possessing low mechanical strength is attributed to peripheral and bulk millimeter-length cracks. The research program is based on feasibility results obtained during Phase I, which established that: (i) the Resonance Ultrasonic Vibrations method is applicable to as-cut, processed wafers and finished cells; (ii) the method sensitivity depends on the specific processing step; it is highest in as-cut wafers and lowest in wafers with metallization pattern and grid contacts; (iii) the system is capable of matching the 2.0 seconds per wafer throughput rate of state-of-art solar cell production lines; (iv) finite element modeling provides vibration mode analysis along with peak shift versus crack length and crack location dependence; (v) a high 91% crack rejection rate was confirmed through experimentation and statistical analysis. The Phase II project has the following specific tasks: (i) specify optimal configurations of the in-line systemâÃÂÃÂs component hardware and software; (ii) develop and justify a system prototype that meets major specifications for an in-line crack detection unit, such as high throughput rate, high level of stability, reproducibility of data acquisition and analysis, and high sensitivity with respect to crack length and crack location; (iii) design a system platform that allows easy integration within and adaptation to various solar cell belt-type production lines; (iv) develop a testing protocol providing quality certification of the production-grade system. Commercial Application of the proposed activity consists of bringing to the solar market a new high-tech product based on an innovative solution and patented methodology to contribute to cost reduction of silicon solar module production. The solar industry, with crystalline silicon as a dominant segment, shows outstanding performance, with approximately 25% yearly growth during the last years. Despite a slowdown with only 5.6 GW installations in 2009, solar module production for the 2010 and 2011 years was recovered. According to European Photonics Industry Consortium new solar PV installations grow by 56% compared to 2010 reached 64.7 GW in 2011. Revenues in the PV industry reached a record high of $93 billion in 2011, a 13.4 percent gain over 2010 â and 150 percent over 2009. This growth was forecasted to continue in 2013 with double digits growth. The solar industry is economically driven to make solar panels of the highest conversion efficiency and reliability at the lowest production cost. The Resonance Ultrasonic Vibration system addresses critical needs of the silicon-based solar industry by providing a quality control method and tool, which will improve productivity, increase reliability of products and reduce manufacturing cost of solar panels

    Luminescence characterization of quantum dots conjugated with biomarkers for early cancer detection

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    Luminescent semiconductor quantum dots (QDs) conjugated with biomolecules to serve as sensitive probes for early detection of the cancer cells, specifically for ovarian cancer and lung cancer, which represents the most lethal malignancies. The luminescence characterization of the bin-conjugated QDs with cancer specific antigens using linkage molecules. Photo-enhancement is measured at various laser density power, temperatures and laser wavelengths

    Light Induced Degradation in Promising Multi-Crystalline Silicon Materials for Solar Cell Fabrication

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    Presented at the 3rd World Conference on Photovoltaic Energy Conversion; Osaka, Japan; May 11-18, 2003.Light induced degradation (LID) in boron doped Czochralski (Cz) silicon with high oxygen content is known to degrade solar cell efficiency. Multicrystalline Si crystals also have oxygen and use B doping, but LID effects are largely unknown. In this paper, ribbon, Cz, and cast multi-crystalline Si crystals with a resistivity of 1-3 Ωcm were investigated for LID. 15-16% efficient EFG, String Ribbon, and cast mc-Si solar cells, fabricated by manufacturable screen printed technology, show small but measurable LID (0.2% absolute efficiency loss). In less than 15% efficient devices, LID was not detectable in ribbon Si crystals. However, >16% efficient photolithography ribbon Si degraded >0.5% absolute. Analysis of the bulk lifetime using photoluminescence mapping, after cell processing, supports the presence of LID in the good regions of the ribbon materials while the defective regions remained essentially unaffected

    Investigation of Spatially Non-Uniform Defect Passivation in EFG Si by Scanning Photoluminescence Technique

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    Presented at the 31st IEEE Photovoltaic Specialists Conference, Orlando, Florida; January 3-7, 2005. ©2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.This paper shows that both hydrogenation of defects from SiN(x) coating and thermally-induced dehydrogenation of defects are rapid and occur simultaneously in EFG Si during cell processing. Room-temperature scanning photoluminescence mappings, before and after the SiN(x) induced hydrogenation, revealed that hydrogenation of defective regions is effective and pronounced, with more than an order of magnitude increase in lifetime, compared to the rest of the bulk. In addition, FTIR measurements showed the concentration of bonded hydrogen in the SiN(x) film decreases with the increase in annealing temperature and time. However, the rate of release of hydrogen from the SiN(x) film decreases sharply after the first few seconds. Based on this understanding, a process was developed for a co-firing of SiN(x) film and screen-printed Al and Ag in RTP unit, which produced 4 cm(2) EFG Si cell with highest efficiency of 16.1%

    Учебно-методический комплекс дисциплины «Международные кредитно-расчетные и валютные операции»

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    Дана навчальна дисципліна є теоретичною основою сукупності знань та вмінь, що формують профіль фахівця з менеджменту зовнішньоекономічної діяльності.Метою викладання дисципліни є ознайомлення студентів з особливостями організації міжнародних кредитних та розрахункових операцій у банках, розрахункових операцій у системі міжнародної торгівлі вітчизняних підприємств та міжнародних компаній.The purpose of the course is to familiarize students with the peculiarities of the organization of international credit and settlement operations in banks, settlement operations in the system of international trade of domestic enterprises and international companies.Целью преподавания дисциплины является ознакомление студентов с особенностями организации международных кредитных и расчетных операций в банках, расчетных операций в системе международной торговли отечественных предприятий и международных компаний.Кафедра менеджменту зовнішньоекономічної діяльност
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