Download or read book Development of N type Selective Emitter Silicon Solar Cells by Laser Doping Using Boron doped Silicon Paste written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Efficiency Crystalline Silicon Solar Cells written by Eun-Chel Cho and published by MDPI. This book was released on 2021-01-06 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is composed of 6 papers. The first paper reports a novel technique for the selective emitter formation by controlling the surface morphology of Si wafers. Selective emitter (SE) technology has attracted renewed attention in the Si solar cell industry to achieve an improved conversion efficiency of passivated-emitter rear-contact (PERC) cells. In the second paper, the temperature dependence of the parameters was compared through the PERC of the industrial-scale solar cells. As a result of their analysis, PERC cells showed different temperature dependence for the fill factor loss as temperatures rose. The third paper reports the effects of carrier selective front contact layer and defect state of hydrogenated amorphous silicon passivation layer/n-type crystalline silicon interface. The results demonstrated the effects of band offset determined by band bending at the interface of the passivation layer and carrier selective front contact layer. In addition, the nc-SiOx: H CSFC layer not only reduces parasitic absorption loss but also has a tunneling effect and field-effect passivation. The fourth paper reports excimer laser annealing of hydrogenated amorphous silicon film for TOPCon solar cell application. This paper analyzes the crystallization of a-Si:H via excimer laser annealing (ELA) and compared this process with conventional thermal annealing. The fifth paper reports the contact mechanism between Ag–Al and Si and the change in contact resistance (Rc) by varying the firing profile. Rc was measured by varying the belt speed and peak temperature of the fast-firing furnace. The sixth paper reports a silicon tandem heterojunction solar cell based on a ZnO/Cu2O subcell and a c-Si bottom subcell using electro-optical numerical modeling. The buffer layer affinity and mobility together with a low conduction band offset for the heterojunction are discussed, as well as spectral properties of the device model.

Download or read book Hydrogen Passivation and Laser Doping for Silicon Solar Cells written by Brett Hallam and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic electricity generation is a rapidly growing industry, and a key pillar of a decarbonised energy system. In modern solar cells, laser technology is used to form localised structures such as a selective emitter through doping or to locally ablate dielectric layers for contact definition. A critical factor is the ability to passivate the laser-induced defects to prevent premature charge carrier recombination reducing the cell efficiency. Hydrogenation is such a passivation technique. The exact mechanisms have until recently been poorly understood, so this timely reference covers the recent breakthroughs in the understanding of hydrogen passivation.

Download or read book Novel Approach for Selective Emitter Formation and Front Side Metallization of Crystalline Silicon Solar Cells written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization and Fundamental Investigation of Laser Doping for Silicon Solar Cells written by Lujia Xu and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced structures with localized contacts can enable high efficiency crystalline silicon solar cells, but they are complex and costly to fabricate using conventional techniques. Hence, the development of new, cheaper processes to produce localized contact regions is of great interest. One of the most promising processes is laser doping. This thesis explores three main areas related to the challenges of laser doping, in particular the characterization of the laser-doped regions, the degradation of the silicon/dielectric interface in the vicinity of the laser-doped regions, and the degradation of the laser processed silicon. A technique named secondary electron microscopy dopant contrast imaging (SEMDCI) is firstly introduced for the characterisation of the cross-section/top-surface of laser-doped samples. This technique can be used for a large range of different dopant sources and different laser doping methods. The technique can be employed to obtain quantitative dopant density images for p-type laser-doped regions, albeit currently over a limited range of dopant densities and with relatively large error. Using this technique, the risk of metallization shunts near the edges of dielectric film windows opened by the laser can be evaluated. Furthermore, this technique is useful for understanding the interaction between different materials during the laser doping process. The impact of the silicon nitride layer thickness in silicon dioxide / silicon nitride stacks on the properties of laser-doped lines is investigated through measurement of the doping profile near the edge of the dielectric window which is an important factor in determining the likelihood of high recombination or even shunting from the subsequent metallization process. Fundamentally, a problem of exposed and undoped silicon near the dielectric window is identified for most of the investigated parameter range. However, optimization of the laser parameters and dielectric film conditions is shown to be capable of preventing or at least minimizing this problem. Beside this problem, the residual dielectrics close to the edge might be degraded after laser process. Therefore, experimental methods are proposed to detect this possible degradation. In the last part of the thesis, boron diffused samples capped with different dielectric films (including bare surfaces) are processed using laser pulses and characterized by photoluminescence imaging (PL) to study the degradation of the electronic properties of the processed regions. In this way, without the interference of a dopant precursor, the thermal and dielectric effects are separately investigated. It is found that the thermal effects do not lead to significant damage and additional recombination, provided no severe silicon evaporation occurs. However, when a dielectric film is present, a considerable increase in recombination is observed irrespective of laser parameters. The magnitude of the increase in recombination varies substantially depending on the dielectric used. It is demonstrated that both sufficient silicon melting and low recombination can in principle be achieved, particularly using long pulse durations and small pulse distances. In addition, nitrogen gas annealing after laser process was proved to be an effective way to reduce the defects induced by both the thermal effects and dielectrics.

Download or read book Heavily Doped Carrier selective Regions for Silicon Solar Cells written by Di Yan and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: While heavily doped regions are an integral part of conventional silicon solar cells for carrier separation and selective transport, they also introduce deleterious effects that constrain their performance. This thesis addresses the fundamental limitations imposed by heavy doping in silicon solar cells and explores the potential of utilising doping in a manner that circumvents them. In particular, selectively doped regions and novel carrier-selective passivating contacts are developed. In heavily doped silicon, energy band gap narrowing (BGN) occurs. Subsequently, the pn product in equilibrium increases, which tends to limit the performance of silicon solar cells. In principle, heavily doped silicon should be analyzed using Fermi-Dirac statistics coupled with a BGN model. Nevertheless, applying Schenk's theoretical BGN model to experimental samples underestimates their corresponding recombination current parameters. Based on a large number of samples and using well-proven models for Auger recombination and carrier mobility, updated empirical expressions for the BGN are derived here for both n-type and p-type silicon. The study confirms that the BGN values in p-type silicon are slightly larger than in n-type silicon. Both updated BGN models contribute to a more complete understanding of the losses and ramifications caused by heavily doped regions in silicon solar cells. A possible approach to reduce the impact of heavily doped regions is to reduce the area they occupy, restricting it to underneath the metal contacts. In this thesis a process to implement such selectively doped (SD) silicon solar cells is developed. The process, based on a controlled etch-back of the diffused region offers the advantage of being self-aligned, which avoids the critical mask alignment step. The TMAH based etch-back solution used here provides a well-controlled etching rate, uniformly etched surface and selectivity to metallic layers (Al or Ag). The poof-of-concept SD silicon solar cells have reached a conversion efficiency of 17.5%. Inspired by silicon heterojunction solar cells and polysilicon emitter BJT, carrier-selective passivating contacts based on heavily doped silicon films are developed. Two approaches of depositing intrinsic polysilicon or amorphous silicon are demonstrated. In both cases, a thermal diffusion process is used to dope and recrystallise the films. The diffusion processes, the intrinsic silicon film thickness, and the interfacial layer conditions are optimized in terms of the trade-off between the recombination current parameter and the contact resistivity. The interfacial layer is found to be critical for blocking the penetration of dopants, for stopping the epitaxial regrowth between the top silicon film and the underlying crystalline silicon, as well as for enhancing the response to a subsequent hydrogenation treatment. Examination of these carrier-selective passivating contact structures before and after the thermal diffusion processes by using XRD, micro-PL and XPS indicates that allowing a moderate level of phosphorus into the silicon oxide and into the silicon substrate is necessary to achieve a low recombination and a low contact resistivity. The electron-selective passivating contacts have been successfully implemented at the rear of n-type silicon solar cells, showing open circuit voltage of > 672 mV and efficiency values up to 20.8%.

Download or read book Energy Efficiency Improvements in Smart Grid Components written by Moustafa Eissa and published by BoD – Books on Demand. This book was released on 2015-04-22 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is intended for academics and engineers who are working in universities, research institutes, utility and industry sectors wishing to enhance their idea and get new information about the energy efficiency developments in smart grid. The readers will gain special experience with deep information and new idea about the energy efficiency topics. This book includes lots of problems and solutions that can easily be understood and integrated into larger projects and researches. The book enables some studies about monitoring, management and measures related to smart grid components, Energy Efficiency Improvements in smart grid components and new intelligent Control strategies for Distributed energy resources, boosting PV systems, electrical vehicles, etc. It included optimization concepts for power system, promoting value propositions; protection in power system, etc. The book also has some recent developments in solar cell technologies, LEDs and non thermal plasma technology. As I enjoyed preparing this book I am sure that it will be very valuable for large sector of readers.

Download or read book Simulation and Process Development for Ion implanted N type Silicon Solar Cells written by Steven Ning and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As the efficiency potential for the industrial P-type Al-BSF silicon solar cell reaches its limit, new solar cell technologies are required to continue the pursuit of higher efficiency solar power at lower cost. It has been demonstrated in literature that among possible alternative solar cell structures, cells featuring a local BSF (LBSF) have demonstrated some of the highest efficiencies seen to date. Implementation of this technology in industry, however, has been limited due to the cost involved in implementing the photolithography procedures required. Recent advances in solar cell doping techniques, however, have identified ion implantation as a possible means of performing the patterned doping required without the need for photolithography. In addition, past studies have examined the potential for building solar cells on N-type silicon substrates, as opposed to P-type. Among other advantages, it is possible to create N-type solar cells which do not suffer from the efficiency degradation under light exposure that boron-doped P-type solar cells are subject to. Industry has not been able to capitalize on this potential for improved solar cell efficiency, in part because the fabrication of an N-type solar cell requires additional masking and doping steps compared to the P-type solar cell process. Again, however, recent advances in ion implantation for solar cells have demonstrated the possibility for bypassing these process limitations, fabricating high efficiency N-type cells without any masking steps. It is clear that there is potential for ion implantation to revolutionize solar cell manufacturing, but it is uncertain what absolute efficiency gains may be achieved by moving to such a process. In addition to development of a solar specific ion implant process, a number of new thermal processes must be developed as well. With so many parameters to optimize, it is highly beneficial to have an advanced simulation model which can describe the ion implant, thermal processes, and cell performance accurately. Toward this goal, the current study develops a process and device simulation model in the Sentaurus TCAD framework, and calibrates this model to experimentally measured cells. The study focuses on three main tasks in this regard: Task I - Implant and Anneal Model Development and Validation This study examines the literature in solar and microelectronics research to identify features of ion implant and anneal processes which are pertinent to solar cell processing. It is found that the Monte Carlo ion implant models used in IC fabrication optimization are applicable to solar cell manufacture, with adjustments made to accommodate for the fact that solar cell wafers are often pyramidally textured instead of polished. For modeling the thermal anneal processes required after ion implant, it is found that the boron and phosphorus cases need to be treated separately, with their own diffusion models. In particular, boron anneal simulation requires accurate treatment of boron-interstitial clusters (BICs), transient enhanced diffusion, and dose loss. Phosphorus anneal simulation requires treatment of vacancy and interstitial mediated diffusion, as well as dose loss and segregation. The required models are implemented in the Sentaurus AdvancedModels package, which is used in this study. The simulation is compared to both results presented in literature and physical measurements obtained on wafers implanted at the UCEP. It is found that good experimental agreement may be obtained for sheet resistance simulations of implanted wafers, as well as simulations of boron doping profile shape. The doping profiles of phosphorus as measured by the ECV method, however, contain inconsistencies with measured sheet resistance values which are not explained by the model. Task II - Device Simulation Development and Calibration This study also develops a 3D model for simulation of an N-type LBSF solar cell structure. The 3D structure is parametrized in terms of LBSF dot width and pitch, and an algorithm is used to generate an LBSF structure mesh with this parametrization. Doping profiles generated by simulations in Task I are integrated into the solar cell structure. Boundary conditions and free electrical parameters are calibrated using data from similar solar cells fabricated at the UCEP, as well as data from lifetime test wafers. This simulation uses electrical models recommended in literature for solar cell simulation. It is demonstrated that the 3D solar cell model developed for this study accurately reproduces the performance of an implanted N-type full BSF solar cell, and all parameters fall within ranges expected from theoretical calculations. The model is then used to explore the parameter space for implanted N-type local BSF solar cells, and to determine conditions for optimal solar cell performance. It is found that adding an LBSF to the otherwise unchanged baseline N-type cell structure can produce almost 1% absolute efficiency gain. An optimum LBSF dot pitch of 450um at a dot size of 100um was identified through simulation. The model also reveals that an LBSF structure can reduce the fill factor of the solar cell, but this effect can be offset by a gain in Voc. Further efficiency improvements may be realized by implementing a doping-dependent SRV model and by optimizing the implant dose and thermal anneal. Task III - Development of a Procedure for Ion Implanted N-type LBSF Cell Fabrication Finally, this study explores a method for fabrication of ion-implanted N-type LBSF solar cells which makes use of photolithographically defined nitride masks to perform local phosphorus implantation. The process utilizes implant, anneal, and metallization steps previously developed at the UCEP, as well as new implant masking steps developed in the course of this study. Although an LBSF solar cell has not been completely fabricated, the remaining steps of the process are successfully tested on implanted N-type full BSF solar cells, with efficiencies reaching 20.0%.

Download or read book Development of High efficiency Boron Diffused Silicon Solar Cells written by Arnab Das and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the proposed research is to develop low-cost, screen-printed 20% efficient silicon solar cells. In the first part of this thesis, a ~19% efficient, screen-printed cell was fabricated using the commercially-dominant aluminum back surface field (Al-BSF) cell structure. Device modeling was then used to determine that increasing the efficiency to 20% required improvements in both back surface passivation and rear reflectance. In the second part of this thesis, a passivated, transparent boron BSF (B-BSF) structure was proposed as a high-throughput method for realizing these improvements. The first step in fabricating the proposed B-BSF cell involved the successful development of a water-based, spin-on solution of boric acid as a low-cost, non-toxic and non-pyrophoric alternative to common boron diffusion sources such as boron tribromide. A review of the literature shows that a common problem with boron diffusion is severe bulk lifetime degradation, with Fe contamination being commonly speculated as the cause. An experimental study was therefore devised in which the impact of boron diffusion and subsequent cell process steps on the bulk lifetime and bulk iron contamination was tracked. From this study, a model for boron diffusion-induced Fe contamination was developed along with methods for gettering Fe from the substrate. A key achievement of this thesis was the discovery of a novel, negatively charged, aluminum-doped spin-on glass (SOG) which can, in a short thermal step, simultaneously getter Fe and provide stable, high-quality passivation of planar, boron-diffused Si surfaces. Since past attempts at achieving low-cost, high-efficiency, boron-diffused cells have suffered from bulk lifetime degradation and difficulties with passivating a boron-diffused Si surface, the Al-doped SOG provides a solution to both challenges. Since a high rear reflectance is important for achieving high-efficiencies, an experimental study of various reflectors was undertaken and a silver colloid material was found which exhibits both high electrical conductivity and Lambertian reflectance>95%. The work on boric acid diffusion, iron gettering, surface passivation and rear reflectors was successfully integrated into a 20.2% efficient, screen-printed, B-BSF cell fabricated on 300 æm thick, p-type float-zone (FZ) Si wafers. Both device theory and modeling was used to show that, due to its well-passivated surfaces, this cell would suffer a large loss in efficiency due to light-induced degradation (LID) if it were fabricated on commercial p-type Czochralski (Cz) Si substrates. Since n-type Si substrates do not suffer from LID, the p-type process was slightly tweaked and applied to n-type FZ wafers, resulting in 20.3% efficient cells on 190 æm thick wafers. Computer modeling shows that both the p-type and n-type cells can maintain efficiencies of 20% for wafers as thin as 100 æm.

Download or read book Photovoltaic Solar Energy written by Angèle Reinders and published by John Wiley & Sons. This book was released on 2017-01-03 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar PV is now the third most important renewable energy source, after hydro and wind power, in terms of global installed capacity. Bringing together the expertise of international PV specialists Photovoltaic Solar Energy: From Fundamentals to Applications provides a comprehensive and up-to-date account of existing PV technologies in conjunction with an assessment of technological developments. Key features: Written by leading specialists active in concurrent developments in material sciences, solar cell research and application-driven R&D. Provides a basic knowledge base in light, photons and solar irradiance and basic functional principles of PV. Covers characterization techniques, economics and applications of PV such as silicon, thin-film and hybrid solar cells. Presents a compendium of PV technologies including: crystalline silicon technologies; chalcogenide thin film solar cells; thin-film silicon based PV technologies; organic PV and III-Vs; PV concentrator technologies; space technologies and economics, life-cycle and user aspects of PV technologies. Each chapter presents basic principles and formulas as well as major technological developments in a contemporary context with a look at future developments in this rapidly changing field of science and engineering. Ideal for industrial engineers and scientists beginning careers in PV as well as graduate students undertaking PV research and high-level undergraduate students.

Download or read book Reduction in Recombination Current Density in Boron Doped Silicon Using Atomic Hydrogen written by Matthew Garett Young and published by . This book was released on 2017 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The solar industry has grown immensely in recent years and has reached a point where solar energy has now become inexpensive enough that it is starting to emerge as a mainstream electrical generation source. However, recent economic analysis has suggested that for solar to become a truly wide spread source of electricity, the costs still need to plummet by a factor of 8x. This demands new and innovative concepts to help lower such cost. In pursuit of this goal, this dissertation examines the use of atomic hydrogen to lessen the recombination current density in the boron doped region of n-type silicon solar cells. This required the development of a boron diffusion process that maintained the bulk lifetime of n-type silicon such that the recombination current density could be extracted by photoconductance spectroscopy. It is demonstrated that by hydrogenating boron diffusions, the majority carrier concentration can be controlled. By using symmetrically diffused test structures with quinhydrone-methanol surface passivation the recombination current density of a hydrogenated boron profile is shown to be less than that of a standard boron profile, by as much as 30%. This is then applied to a modified industrial silicon solar cell process to demonstrate an efficiency enhancement of 0.4%

Download or read book Contact Formation on Boron Doped Silicon Substrates from Passivating PECV deposited Dielectric Doping Layers with Anti reflective Properties by Screen printing Ag Pastes for High efficiency N type Silicon Solar Cells written by Josh Engelhardt and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanostructured Solar Cells written by Narottam Das and published by BoD – Books on Demand. This book was released on 2017-02-22 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured solar cells are very important in renewable energy sector as well as in environmental aspects, because it is environment friendly. The nano-grating structures (such as triangular or conical shaped) have a gradual change in refractive index which acts as a multilayer antireflective coating that is leading to reduced light reflection losses over broadband ranges of wavelength and angle of incidence. There are different types of losses in solar cells that always reduce the conversion efficiency, but the light reflection loss is the most important factor that decreases the conversion efficiency of solar cells significantly. The antireflective coating is an optical coating which is applied to the surface of lenses or any optical devices to reduce the light reflection losses. This coating assists for the light trapping capturing capacity or improves the efficiency of optical devices, such as lenses or solar cells. Hence, the multilayer antireflective coatings can reduce the light reflection losses and increases the conversion efficiency of nanostructured solar cells.

Download or read book Aluminum Oxide for the Surface Passivation of High Efficiency Silicon Solar Cells written by Armin Richter and published by . This book was released on 2015-02-23 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Fabrication and Performance of a 20 Percent Efficient Silicon Solar Cell written by Jose L. Rodriguez and published by . This book was released on 1980 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Front Side Technology on Crystalline Silicon Solar Cells written by and published by Victor Prajapati. This book was released on with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Efficiency Silicon Solar Cells written by Martin A. Green and published by Trans Tech Publications Ltd. This book was released on 1987-01-01 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The early chapters comprehensively review the optical and transport properties of silicon. Light trapping is described in detail. Limits on the efficiency of silicon cells are discussed as well as material requirements necessary to approach these limits. The status of current approaches to passifying surfaces, contacts and bulk regions is reviewed. The final section of the book describes the most practical approaches to the fabrication of high-efficiency cells capable of meeting the efficiency targets for both concentrated and non-concentrated sunlight, including a discussion of design and processing approaches for non-crystalline silicon.