Download or read book Optimization of Interdigitated Back Contact Silicon Heterojunction Solar Cells by Two dimensional Numerical Simulation written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, two-dimensional (2D) simulation of interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells is presented using Sentaurus Device, a software package of Synopsys TCAD. A model is established incorporating a distribution of trap states of amorphous-silicon material and thermionic emission across the amorphous-silicon / crystalline-silicon heterointerface. The 2D nature of IBC-SHJ device is evaluated and current density-voltage (J-V) curves are generated. Optimization of IBC-SHJ solar cells is then discussed through simulation. It is shown that the open circuit voltage (VOC) and short circuit current density (JSC) of IBC-SHJ solar cells increase with decreasing front surface recombination velocity. The JSC improves further with the increase of relative coverage of p-type emitter contacts, which is explained by the simulated and measured position dependent laser beam induced current (LBIC) line scan. The S-shaped J-V curves with low fill factor (FF) observed in experiments are also simulated, and three methods to improve FF by modifying the intrinsic a-Si buffer layer are suggested: (i) decreased thickness, (ii) increased conductivity, and (iii) reduced band gap. With all these optimizations, an efficiency of 26% for IBC-SHJ solar cells is potentially achievable.
Download or read book Interdigitated Back Contact Silicon Solar Cell Analysis and Design Recommendations for Space Use written by D. C. Marvin and published by . This book was released on 1989 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Interdigitated Back Contact (IBC) solar cell is a relatively new design which has shown unprecedentedly high efficiencies. Silicon Interdigitated Back Contact cells have been fabricated that show greater than 25% efficiency at 100 suns Air Mass 1.5. This is far superior to conventional silicon concentrator cells which are approximately 18% efficient. The purpose of this report is to describe briefly the differences between this technology and conventional cells, demonstrate a near optimum design achieved by two-dimensional numerical simulation, and assess the utility of these cells for space application. The end of life (EOL) performance of this cell design in the radiation environment of space is a critical issue since the high efficiency of the design is predicated on the use of very high quality, long-diffusion length silicon. The radiation-induced degradation of this material is expected to lead to severe efficiency losses. The optimization of cell design to minimize these losses was carried out using a modified version of the 2-dimensional PISCES semiconductor simulator. The final designs presented here show that the performance of IBC cells in space can significantly exceed that of conventional cells. PISCES Simulator, Electric power production, Power supplies, Solar cells, Semiconductors. (jg).
Download or read book Junction Engineering and Device Design for Silicon Heterojunction and Interdigitated Back Contact Silicon Heterojunction Solar Cells written by Lei Zhang and published by . This book was released on 2018 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell currently holds the record conversion efficiency for non-concentrated single junction silicon solar cells with an efficiency of 26.7%. The aim of this dissertation is to understand the fundamental loss mechanisms of IBC-SHJ related to the rear surface design and to minimize these losses utilizing advanced numerical simulations, novel test structure characterizations and scalable device fabrication processes. The findings in this dissertation will serve as guidance for the industry-oriented R & D efforts to make IBC-SHJ mass-production cost-effective without compromising the performance. The outcomes of this dissertation are four-fold: ☐ First, a lifetime simulation tool based on the extended Shockley-Read-Hall (SRH) recombination formalism has been developed as guidance to investigate c-Si surface passivation. Plasma enhanced chemical vapor deposition (PECVD) conditions of intrinsic hydrogenated amorphous silicon (i.a-Si:H) films were explored for passivating the commercial n-type c-Si (n.c-Si) wafer surfaces and correlation to the properties of films was established through material characterizations. Passivated lifetime > 1ms with implied open circuit voltage (iVOC) > 700 mV has been achieved. The trade-off between front surface absorption loss and rear surface emitter junction valence band offset effect was simultaneously accommodated with an optimized i.a-Si:H layer. ☐ Second, an advanced two-dimensional (2-D) IBC-SHJ simulation model has been developed to investigate the IBC-SHJ device rear surface design of three regions: emitter contact, base contact and the non-metallized gap region between them. Simulations suggested that IBC-SHJ performance is more sensitive to the surface passivation quality in emitter and gap regions than the base region. The trade-offs between VOC and FF were diagnosed by experimentally varying p-type a-Si:H layers (p.a-Si:H) and their application on SHJ test structures. A graded high-low p.a-Si:H emitter structure was established, demonstrating IBC-SHJ solar cell efficiency of 20.2% fabricated by complex three-step photolithography (PL) process. ☐ Thirdly, to minimize the lateral transport loss over the rear surface gap region, four different passivation structures were investigated utilizing potential industrially-scalable process. Interface defect density (Dit) and interface charge density (Qpass) for the four structures were extracted utilizing a lifetime simulator. The 2-D IBC-SHJ device simulations indicated that > 21.5% conversion efficiency is achievable on devices fabricated with our current process. However, experimental results of IBC-SHJ fabricated with simplified processes suggested that a gap passivation structure which induces inversion at n.c-Si surface should be avoided. ☐ Fourth, to validate the inversion layer effect on IBC-SHJ device, a novel three-terminal rear SHJ test structure was invented. This structure enabled an external DC bias to be applied onto one of the rear contacts for voltage-modulated laser-beam-induced-current (VM-LBIC) measurements. Additionally, device performance was analyzed before and after intentional localized laser damage to base region, which confirmed the detrimental surface inversion effect if any localized high surface recombination region exists within a diffusion length distance from emitter region. ☐ Based on these results, for a commercially viable IBC-SHJ fabrication on n-type c-Si wafer, the following recommendations can be made: 1) Avoid passivation scheme with negative charge that might form inversion layer at the rear surface; 2) Minimize area of localized defective regions with high surface recombination velocity (SRV) and; 3) Low resolution alignment patterning processes which yield gap widths ≥ 100 μm are acceptable if the gap region of IBC-SHJ has an SRV ≤ 5 cm/s.
Download or read book Interdigitated Back Contact Silicon Heterojunction Solar Cells written by John Allen and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Interdigitated back contact silicon hetero-junction (IBC-SHJ) solar cells using a-Si emitter and contact layers show significant potential advantages over standard hetero-junction devices: higher short-circuit current (Jsc) since there is no grid shading and higher open-circuit voltage (Voc) due to better surface passivation. However, they often suffer from low fill factor (FF). IBC-SHJ processing steps include two separate photoresist masks for doped amorphous silicon depositions, and all amorphous layers are deposited using Plasma Enhanced Chemical Vapor Deposition (PECVD). The thicknesses of the front surface layers are optimized so that reflection and absorption are minimized. Measurement techniques, such as current-voltage, reflection, and quantum efficiency, were used to characterize the experimental devices. These techniques were also investigated in simulations to match modeled data to experimental results. Using two-dimensional simulations to model IBC-SHJ devices on Float Zone (FZ) n-Si, we found that the FF was nearly independent of the defect concentrations in contact and passivating i-layers but strongly dependent on the defects in emitter and the band gap in the rear i-layer. Voc and Jsc were nearly independent of defects in either doped layer. In a-Si doped layers it is well known that the number of defects increase with doping. We find that the FF is sensitive to either mid-gap or band tail states and that S-shaped JV curves responsible for low FF can be eliminated by a decrease in p-layer mid-gap or band tail defect levels, or by decreasing the rear i-layer's band gap. The insensitivity of FF to defects in the n-layer or in the i-layer suggests the FF is dominated by minority carrier injection/collection from the p-type emitter layer. The dependence of FF on the rear i-layer band gap suggests that increasing the offset in the valence band impedes minority carrier collection. Rear-surface geometry, wafer resistivity, and wafer lifetime and thickness were also investigated in simulations, and their results are shown. With the advancement of IBC-SHJ technology, new device structures, such as larger cells with more interdigitated fingers, will be fabricated and simulated.
Download or read book Silicon Heterojunction Solar Cells written by W.R. Fahrner and published by Trans Tech Publications Ltd. This book was released on 2006-08-15 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The world of today must face up to two contradictory energy problems: on the one hand, there is the sharply growing consumer demand in countries such as China and India. On the other hand, natural resources are dwindling. Moreover, many of those countries which still possess substantial gas and oil supplies are politically unstable. As a result, renewable natural energy sources have received great attention. Among these, solar-cell technology is one of the most promising candidates. However, there still remains the problem of the manufacturing costs of such cells. Many attempts have been made to reduce the production costs of conventional solar cells (manufactured from monocrystalline silicon using diffusion methods) by instead using cheaper grades of silicon, and simpler pn-junction fabrication. That is the hero of this book; the heterojunction solar cell.
Download or read book Two dimensional Numerical Optimisation Study of the Rear Contact Geometry of High efficiency Silicon Solar Cells written by Armin G. Aberle and published by . This book was released on 1993 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Under one-sun illumination, the highest energy conversion efficiencies of silicon solar cells are presently obtained with bifacially contacted n+p cells, where contact to the p-type substrate is made via small openings in the rear passivating oxide. In this work, a state-of-the-art 2-dimensional (2D) semi-conductor device simulator is applied to these devices in order to investigate the effects arising from the rear metallisation scheme. The impact of various cell parameters (i.e. substrate resistivity, rear surface recombination model (flatband or surface band bending conditions), positive oxide charge density, capture cross section ratio) on the cell's current-voltage (I-V) characteristics and the optimum rear contact spacing is investigated. For the first time the experimentally observed highly non-ideal I-V curves of rear point- contacted high-efficiency silicon solar cells made at the University of New South Wales (UNSW) have been modelled with a high degree of accuracy. This is achieved by properly accounting for the complex recombination behaviour at the rear oxidised surface. The 2D simulations show that the non-ideal I-V curves result from the unequal capture cross sections of electrons and holes at the rear Si-SiO2 interface and the surface band bending induced by positive oxide charges and metal/silicon work function differences. For the UNSW cells, optimum one-sun efficiency is obtained on 2 Ohm cm substrates and rear contact spacings of 0.2-0.3 mm. The 2d simulations presented in this work clearly confirm the experimental findings and reveal the physical mechanisms which favour this particular contact design."
Download or read book 3D Stacked Chips written by Ibrahim (Abe) M. Elfadel and published by Springer. This book was released on 2016-05-11 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explains for readers how 3D chip stacks promise to increase the level of on-chip integration, and to design new heterogeneous semiconductor devices that combine chips of different integration technologies (incl. sensors) in a single package of the smallest possible size. The authors focus on heterogeneous 3D integration, addressing some of the most important challenges in this emerging technology, including contactless, optics-based, and carbon-nanotube-based 3D integration, as well as signal-integrity and thermal management issues in copper-based 3D integration. Coverage also includes the 3D heterogeneous integration of power sources, photonic devices, and non-volatile memories based on new materials systems.
Download or read book Silicon Based Thin Film Solar Cells written by Roberto Murri and published by Bentham Science Publishers. This book was released on 2013-03-20 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon Based Thin Film Solar Cells explains concepts related to technologies for silicon (Si) based photovoltaic applications. Topics in this book focus on ‘new concept’ solar cells. These kinds of cells can make photovoltaic power production an economically viable option in comparison to the bulk crystalline semiconductor technology industry. A transition from bulk crystalline Si solar cells toward thin-film technologies reduces usage of active material and introduces new concepts based on nanotechnologies. Despite its importance, the scientific development and understanding of new solar cells is not very advanced, and educational resources for specialized engineers and scientists are required. This textbook presents the fundamental scientific aspects of Si thin films growth technology, together with a clear understanding of the properties of the material and how this is employed in new generation photovoltaic solar cells. The textbook is a valuable resource for graduate students working on their theses, young researchers and all people approaching problems and fundamental aspects of advanced photovoltaic conversion.
Download or read book Two dimensional numerical optimisation study of the rear contract geometry of high efficiency silicon solar cells written by and published by . This book was released on 1993 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Beyond CMOS Nanodevices 1 written by Francis Balestra and published by John Wiley & Sons. This book was released on 2014-06-02 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a comprehensive review of the state-of-the-art in innovative Beyond-CMOS nanodevices for developing novel functionalities, logic and memories dedicated to researchers, engineers and students. It particularly focuses on the interest of nanostructures and nanodevices (nanowires, small slope switches, 2D layers, nanostructured materials, etc.) for advanced More than Moore (RF-nanosensors-energy harvesters, on-chip electronic cooling, etc.) and Beyond-CMOS logic and memories applications.
Download or read book I Optimization of Interdigitated Back Contact Silicon Hetero junction IBC SHJ Solar Cell Fabrication Process II Passive Tuning of Optical Couplers written by Ugochukwu J. Nsofor and published by . This book was released on 2019 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: The commercial dominance of Si solar cells has been driven by progress in their conversion efficiencies coupled with their long-term durability and widespread knowledge-base for making standardized devices. Recent record efficiency Si solar cells have utilized a relatively new device architecture incorporating Si heterojunction (SHJ) -- due to their remarkable high open circuit voltage (Voc) and low thermal budget. The focus of my research involves the optimization of SHJ fabrication processing to improve conversion efficiency and application to another high-efficiency concept -- the interdigitated back contact (IBC) structure.
Download or read book Optimization of the PEDOT PSS SiNW Hybrid Solar Cells and All back contact GaAs Solar Cells with Two Dimensional Simulation written by 何冠穎 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 Two dimensional Numerical Modeling of High efficiency Silicon Solar Cells written by Pietro P. Altermatt and published by . This book was released on 1994 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two dimensional Numerical Simulations of High efficiency Silicon Solar Cells written by University of New South Wales. School of Computer Science and Engineering and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "This paper reports on the first use of two-dimensional (2D) device simulation for optimising the front-finger spacing of one-sun high-efficiency silicon solar cells of practical dimensions. We examine the 2D current flow patterns in these devices under various illumination conditions, resulting in improved insight into the operating conditions of the cells. Results for the optimal spacing of the front metal fingers are presented and compared to predictions obtained from 1D simulations. We also address difficulties facing the numerical modelling of high-efficiency silicon solar cells."
Download or read book Two Dimensional Computer Analysis of the Interdigited Back Contact Solar Cell written by Daeje Chin and published by . This book was released on 1979 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interdigitated Back Contacts Solar Cell Based on Thin Crystalline Silicon Substrates written by Chen Jin and published by . This book was released on 2019 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis contributes to the fabrication technology of c-Si solar cells on thin substrates based on Interdigitated Back-Contacted (IBC) structures. The potential of this structure to obtain high efficiencies is well-known. However, important challenges should be addressed to adapt it to thin c-Si substrates, such as the manufacturing of the thin c-Si substrate itself, light absorption enhancement, device structure design, surface passivation, etc. Focused on these challenges, experiments and simulations have been carried out, including innovative thin c-Si substrate fabrication method Millefeuille process, novel IBC solar cell structures combining laser doping and silicon heterojunction technologies and thin IBC solar cell performance prediction through simulation. Finally, a 30 μm thick c-Si solar cell is fabricated by thinning down a finished device applying a silicon etching technique that combines dry and wet etching. Considering the Millefeuille process, based on the technological know-how the impact of both modulated profile and periodicity of silicon pores on the generated thin layer quality is explored and the results are visualized by SEM images. Furthermore, the solid-void transformation evolution during the high temperature annealing reveals the pore status at 35, 60 and 90 minutes, allowing a deeper understanding of the practical silicon atomic surface diffusion and the shape evolution. In order to find a viable and promising device structure that can be used in case of thin silicon substrates, a hybrid p-type solar cell structure is reported. In this case, emitter is based on silicon heterojunction technology while the base contacts are created by laser processing Al2O3/SiCx films. Special attention of the compatibility of both technologies has been paid in the proposed fabrication process including emitter region re-passivation and contact metallization. This work provides a new approach for achieving low-temperature high efficiency c-Si solar cells, as well as a novel pathway compatible to the fabrication of IBC devices based on thin c-Si substrate.In parallel with experimental progress, the simulation on thin c-Si IBC solar cell is carried out for performance study and prediction involving two typical rear surface doping structures: fully- and locally-doped. Simulation results of fully-doped structure reveal an efficiency potential of 16-17 % for thin c-Si IBC solar cell based on substrates of 10-15 μm without changing the technology developed for thick ones. Regarding the locally-doped structure, its performance is less tolerant to the degradation of front surface passivation. Additionally, a strong reduction of short-circuit current related to stronger requirements in the effective diffusion length is also deduced. Finally, a reduction of saturation current density, probably related to a change in the distribution of current that flow parallel to the rear surface, is also observed when the device is slimmed down. Next, a thin IBC c-Si solar cell efficiency potential is explored through rear contacts pitch study and the highest conversion efficiency is expected when contact pitches are minimum in the range of study. Finally, efforts are paid to get a thin c-Si solar cell through thinning down an already finished device of thick substrate. A silicon etching process based on RIE and wet chemical etching is proposed. Different experiments demonstrate that the front surface can be successfully repassivated after etching process. Additionally, random pyramids are created on that surface and the optical response of thin c-Si substrates is measured revealing a potential photogenerated current in the range of 40 mA/cm2 for 30 μm-thick substrates. Applying all these techniques to a final device, a 12.1 % efficiency is achieved and the front surface recombination velocity is deduced to be 1500 cm/s by comparing EQE with simulation results.
