Studies Of Silicon Oxide Ageing And Titanium Oxide Passivation Of Silicon For Use In Solar Cells
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Studies Of Silicon Oxide Ageing And Titanium Oxide Passivation Of Silicon For Use In Solar Cells
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Author : Andrew Francis Thomson
language : en
Publisher:
Release Date : 2010
Studies Of Silicon Oxide Ageing And Titanium Oxide Passivation Of Silicon For Use In Solar Cells written by Andrew Francis Thomson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
These studies improve the understanding of SiO2-Si interface passivation and investigate methods for applying passivating AR coatings. These measures could improve the efficiency and reduce the cost of a solar cell, ultimately reducing the cost of renewable energy.
Novel Uses Of Titanium Dioxide For Silicon Solar Cells
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Author : Bryce Sydney Richards
language : en
Publisher:
Release Date : 2002-10-01
Novel Uses Of Titanium Dioxide For Silicon Solar Cells written by Bryce Sydney Richards and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-10-01 with Solar cells categories.
Evaluation Of Transition Metal Oxide As Carrier Selective Contacts For Silicon Heterojunction Solar Cells
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Author :
language : en
Publisher:
Release Date : 2015
Evaluation Of Transition Metal Oxide As Carrier Selective Contacts For Silicon Heterojunction Solar Cells written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
"Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical band alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of surface passivation. In complement, we construct full device structures incorporating in some cases surface passivation schemes, with measured initial conversion efficiency over 15% and evaluate the carrier transport properties using temperature-dependent current-voltage and capacitance-voltage measurements. With this detailed characterization study, we aim at providing the framework to assess the potential of a material as a carrier selective contact and the understanding of how each of the aforementioned parameters on the metal oxide films influence the full solar cell operating performances.
Effective Passivation Of The Low Resistivity Silicon Surface By A Rapid Thermal Oxide Pecvd Silicon Nitride Stack And Its Application To Passivated Rear And Bifacial Si Solar Cells
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Author :
language : en
Publisher:
Release Date : 1998
Effective Passivation Of The Low Resistivity Silicon Surface By A Rapid Thermal Oxide Pecvd Silicon Nitride Stack And Its Application To Passivated Rear And Bifacial Si Solar Cells written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
A novel stack passivation scheme, in which plasma silicon nitride (SiN) is stacked on top of a rapid thermal SiO2 (RTO) layer, is developed to attain a surface recombination velocity (S) approaching 10 cm/s at the 1.3 [Omega]-cm p-type (100) silicon surface. Such low S is achieved by the stack even when the RTO and SiN films individually yield considerably poorer surface passivation. Critical to achieving low S by the stack is the use of a short, moderate temperature anneal (in this study 730 C for 30 seconds) after film growth and deposition. This anneal is believed to enhance the release and delivery of atomic hydrogen from the SiN film to the Si-SiO2 interface, thereby reducing the density of interface traps at the surface. Compatibility with this post-deposition anneal makes the stack passivation scheme attractive for cost-effective solar cell production since a similar anneal is required to fire screen-printed contacts. Application of the stack to passivated rear screen-printed solar cells has resulted in V{sub oc}'s of 641 mV and 633 mV on 0.65 [Omega]-cm and 1.3 [Omega]-cm FZ Si substrates, respectively. These V{sub oc} values are roughly 20 mV higher than for cells with untreated, highly recombinative back surfaces. The stack passivation has also been used to form fully screen-printed bifacial solar cells which exhibit rear-illuminated efficiency as high as 11.6% with a single layer AR coating.
Ion Implantation For Silicon Solar Cells
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Author : Thomas James Ratcliff
language : en
Publisher:
Release Date : 2015
Ion Implantation For Silicon Solar Cells written by Thomas James Ratcliff and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Ion implantation is investigated as a method for forming the heavily doped regions of silicon solar cells. Research is conducted with the aim of implementing ion implantation into the fabrication process of the Australian National University's interdigitated back contact and Sliver solar cell designs. High temperature annealing of boron and phosphorus implanted silicon is investigated, with an emphasis on thermal oxidation. The effect of annealing ambient on B implanted Si is studied, with an oxidising ambient shown to result in higher carrier recombination and lower dopant activation compared with annealing in an inert ambient. The effect of process temperature during inert annealing of B implanted Si is investigated. The impact of implantation damage for B implanted Si after high temperature annealing is quantified and used to identify the regimes of implantation damage by their impact on electron-hole recombination as a function of implantation fluence and sheet resistance. The defects present after annealing B implanted Si are studied and related to the observed trends in recombination. An oxidation recipe optimised to minimise recombination after B implantation is developed by minimising oxidation time and including a high temperature inert anneal prior to oxidation. The temperature dependence of P implanted Si during thermal oxidation is investigated for a range of implantation fluences. It is found samples that provided the samples is completely amorphised during implantation, annealing at 900 degrees Celsius is as effective as 1050 degrees Celsius. Studies of recombination and contact resistivity are used to design a P implanted point contact for an interdigitated back contact solar cell. Solid phase epitaxial regrowth is used to anneal P implanted Si at 600 degrees Celsius for 10 minutes. The enhancement in dielectric etch rate after implantation is used as a method to form self-aligned, localised doping and electrical contacts. Implanting dopant atoms through a dielectric layer locally enhances the etch rate relative to non-implanted regions of the same dielectric. Chemical etching selectively exposes on the regions doped by implantation while passivation is preserved in the surround dielectric. Laser processing is investigated as a low thermal budget technique to anneal implanted Si. Laser doping from a dielectric layer implanted with dopant atoms is presented as a method for forming self-aligned doping and contacts. This method was demonstrated using a dielectric stack of silicon oxide and silicon nitride implanted with P and an a-Si passivation layer implanted with B. Ion implantation is used to fabricate interdigitated back contact and Sliver solar cells, achieving significant process simplification compared with reference fabrication processes. The fabrication process for each cell type is reduced to a single high temperature step only. For Sliver cells, conversion efficiency of 16% is achieved and efficiency greater than 22% is demonstrated for interdigitated back contact cells, where implantation does not limit the cell performance.
Surface Passivation Of Industrial Crystalline Silicon Solar Cells
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Author : Joachim John
language : en
Publisher: Institution of Engineering and Technology
Release Date : 2018-07-31
Surface Passivation Of Industrial Crystalline Silicon Solar Cells written by Joachim John and has been published by Institution of Engineering and Technology this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-07-31 with Technology & Engineering categories.
This timely, comprehensive work on solar cell surface passivation will collect and convey the scientific and technological progress provided by universities, research institutes and companies to implement dielectric passivation layers into the solar cell manufacturing process for c-Si solar cells. With a focus on industrial manufacturing it will comprehensively cover all promising techniques and describe the process from material research to full production implementation of dielectric layers for silicon solar cell passivation.
Physics Briefs
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Author :
language : en
Publisher:
Release Date : 1994-07
Physics Briefs written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994-07 with Physics categories.
High Efficiency Silicon Solar Cells
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Author : Martin A. Green
language : en
Publisher: Trans Tech Publications Ltd
Release Date : 1987-01-01
High Efficiency Silicon Solar Cells written by Martin A. Green and has been published by Trans Tech Publications Ltd this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987-01-01 with Technology & Engineering categories.
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.
Highly Transparent And Highly Passivating Silicon Nitride For Solar Cells
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Author : Yimao Wan
language : en
Publisher:
Release Date : 2014
Highly Transparent And Highly Passivating Silicon Nitride For Solar Cells written by Yimao Wan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Plasma-enhanced chemical vapor deposition categories.
This thesis concerns the optimisation and application of Silicon nitride (SiNx) films for silicon solar cells. Systematic and comprehensive studies of SiNx properties are undertaken to advance (i) the technology of SiNx synthesised by plasma enhanced chemical vapour deposition (PECVD), and (ii) the understanding of recombination at SiNx-passivated silicon surfaces. We examine the film properties of SiNx prepared by a microwave/radio-frequency dual-mode PECVD reactor. It is shown that there is no universal correlation between surface recombination and (i) bulk structural properties such as chemical bond densities, and (ii) bulk optical properties such as refractive index and extinction coefficient. Results of this study repudiate the common perception that surface recombination decreases as SiNx becomes Si-rich. The finding introduces the potential to independently control the optical and surface recombination properties of SiNx. This is of great importance for the industrial application of SiNx films to photovoltaic cells, as it allows the front surface transmission to be maximised while still attaining outstanding surface passivation. We attain a low and relatively constant surface recombination over a wide range of SiNx refractive indices. Notably, the behaviour is observed on several types of silicon surface surfaces-planar, textured, p-type, n-type, diffused and undiffused-with direct relevance to most silicon solar cell structures. The results confirm that the trade-off between the optical transmission and surface recombination is circumvented. In specific, we attain a highly transparent and highly passivating SiNx film. The value of this film is demonstrated on an n-type interdigitated back contact solar cell with no front surface diffusion, which makes the cell highly susceptible to the front surface passivation. On such a cell, the optimum SiNx developed in this thesis enables a conversion efficiency of 24.4 +/- 0.5% under standard testing conditions (25 Celsius degrees, AM1.5G spectrum). Besides the significant improvement in optical transmission and surface passivation, the results of this thesis also advance the current understanding of recombination at SiNx-passivated silicon surfaces. It is found that an increase in recombination of the textured surfaces is related to the presence of vertices and/or edges of the pyramids rather than to the presence of {111}-orientated facets. Furthermore, this thesis demonstrates that the increase in recombination introduced by (i) a lower pressure, leading to a higher refractive index, (ii) a higher NH3:SiH4 ratio, leading to a lower refractive index, and (iii) the vertices and/or edges of the pyramids, is primarily attributable to an increase in interface defect density rather than a decrease in SiNx charge density. In addition, we hypothesise that the increase in interface defect density is caused by an ion bombardment of the silicon surface at a lower pressure, and by an excessive incorporation of NHb radicals into the SiNx film network at a higher NH3:SiH4 ratio. The satisfactory resolution of the trade-off between optical transmission and surface passivation, and the improved understanding of recombination at SiNx-passivated silicon surfaces, represent significant contributions to the science and technology of silicon solar cells.
Hydrogen Transport From Dielectrics To Poly Si Siox Passivating Contacts Measured By Mass Spectrometry And Vibrational Spectroscopy
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Author :
language : en
Publisher:
Release Date : 2022
Hydrogen Transport From Dielectrics To Poly Si Siox Passivating Contacts Measured By Mass Spectrometry And Vibrational Spectroscopy written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
We demonstrate the relationship between Si solar cell passivation and hydrogen content of various passivating films, including hydrogenated amorphous silicon (a-Si:H), aluminum oxide (Al2O3), silicon nitride (SiNx) and combinations thereof. Through isotopic studies using quadrupole mass spectrometry (QMS), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy, we determine how hydrogen content and stability within each type of film relates to final passivation quality of solar cell test structures. Si solar cells using polycrystalline silicon on silicon oxide (poly-Si/SiOx) passivating contacts are at the forefront of Si solar cell research and emerging as top performers within industrial production. Performance of passivating contact Si solar cells is largely determined by a parameter known as the open-circuit voltage Voc, which directly relates to material quality within the bulk of the device and at surfaces. High Voc is achieved when defects within the bulk crystalline silicon (c-Si) and at interfaces are passivated, preventing them from acting as charge carrier recombination centers. One of the most important means of passivating defects within Si solar cells is via hydrogenation, injecting the cells with large amounts of H to satisfy dangling bonds in the bulk and at interfaces. Hydrogen is especially important in deactivating a prevalent defect in industrial p-type devices which leads to decreased device performance over long-term exposure to light, called light-induced degradation (LID). Some of the most common materials used to supply H to devices are a-Si:H, Al2O3, and SiNx, which can contain very large amounts of H. Upon annealing at elevated temperatures, the hydrogen becomes mobile enough to find and disable defect sites. However, too much hydrogen can also be problematic, sometimes leading to an effect called light and elevated temperature induced degradation (LeTID). It has been shown that these films passivate the interfaces of poly-Si passivating contacts differently, leading to differing performance. Though Al2O3 is a well-defined dielectric material, SiNx can have many different values of x depending on precursor gases and deposition conditions. We observe different FTIR and Raman spectra from different SiNx over a range of x values films to determine the bonding environments within them and further correlate the relative concentrations of Si, N, and H to the stability of H within SiNx and the passivation performance of each film. Because deuterium is chemically identical to hydrogen within these systems, but gives different signals in FTIR and Raman spectroscopy as well as in QMS, isotopic substitution can be used as an excellent tool to probe the H within films. In addition to measuring the H and D bonding within films using FTIR and Raman spectroscopy, we will use such isotopic experiments to observe H and D movement out of these hydrogenating films at elevated temperatures using QMS to determine the stability of H bonding within such systems. With these films characterized based on elemental composition, we will relate such measurements to passivation quality of these films and combinations thereof on poly-Si/SiOx contact structures using quasi-steady state photoconductance decay measurements to obtain implied open-circuit voltage (iVoc) and saturation current density J0 values. Such investigations into the performance of different passivating films and film stacks will lead to greater understanding of dielectrics in semiconductor devices, further improvements in passivated contact design, and eventually, greater proliferation of renewable solar energy worldwide.