Download or read book Intrinsic and doped amorphous silicon carbide films for the surface passivation of silicon solar cells written by Dominik Suwito and published by . This book was released on 2011 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Silicon Carbide Passivating Layers to Enable Higher Processing Temperature in Crystalline Silicon Heterojunction Solar Cells written by and published by . This book was released on 2015 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Very efficient crystalline silicon (c-Si) solar cells have been demonstrated when thin layers of intrinsic and doped hydrogenated amorphous silicon (a-Si:H) are used for passivation and carrier selectivity in a heterojunction device. One limitation of this device structure is the (parasitic) absorption in the front passivation/collection a-Si:H layers; another is the degradation of the a-Si:H-based passivation upon temperature, limiting the post-processes to approximately 200°C thus restricting the contacting possibilities and potential tandem device fabrication. To alleviate these two limitations, we explore the potential of amorphous silicon carbide (a-SiC:H), a widely studied material in use in standard a-Si:H thin-film solar cells, which is known for its wider bandgap, increased hydrogen content and stronger hydrogen bonding compared to a-Si:H. We study the surface passivation of solar-grade textured n-type c-Si wafers for symmetrical stacks of 10-nm-thick intrinsic a-SiC:H with various carbon content followed by either p-doped or n-doped a-Si:H (referred to as i/p or i/n stacks). For both doping types, passivation (assessed through carrier lifetime measurements) is degraded by increasing the carbon content in the intrinsic a-SiC:H layer. Yet, this hierarchy is reversed after annealing at 350°C or more due to drastic passivation improvements upon annealing when an a-SiC:H layer is used. After annealing at 350°C, lifetimes of 0.4 ms and 2.0 ms are reported for i/p and i/n stacks, respectively, when using an intrinsic a-SiC:H layer with approximately 10% of carbon (initial lifetimes of 0.3 ms and 0.1 ms, respectively, corresponding to a 30% and 20-fold increase, respectively). For stacks of pure a-Si:H material the lifetimes degrade from 1.2 ms and 2.0 ms for i/p and i/n stacks, respectively, to less than 0.1 ms and 1.1 ms (12-fold and 2-fold decrease, respectively). For complete solar cells using pure a-Si:H i/p and i/n stacks, the open-circuit voltage (Voc) drops from 720 mV to 600 mV when annealing the device at 350°C. Yet, the Voc of devices using an intrinsic a-SiC:H layer with around 10% carbon content in the i/p stack is more resilient to such process, dropping from 710 mV to 690 mV. Also, irrespective of annealing, the slightly improved transparency of a-SiC:H layers allows about 1% current gain due to a better blue-light response. Active-area efficiencies above 20% are thus obtained for particular carbon content conditions, slightly higher than for devices using only a-Si:H. Even for a-SiC:H layers with bandgaps of up to 2.1 eV, good hole collection is maintained (with fill factors of 67% for devices using intrinsic a-SiC:H in the i/p stack, compared to 73% for the reference device). However, S-shaped current-voltage curves were obtained for devices using such a-SiC:H layers in the i/n stack, indicating impeded transport, which would suggest that most of the bandgap increase translates in a conduction-band offset.
Download or read book Crystalline Silicon Surface Passivation by Amorphous Silicon Compounds written by Roman Petres and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2011-09 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar cells based on crystalline silicon (c-Si) have the potential to make photovoltaic electricity cheaper than coal-based electric power generation within less than 10 years. The largest cost decrease potential on the cell level lies with improved electronic surface passivation. In this work, the current industry standard, amorphous silicon nitride (a-SiNx: H) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD), is investigated and compared to amorphous silicon carbide, silicon carbonitride and silicon oxynitride films deposited by both high- and for the first time also low-frequency (LF) PECVD. It is shown that and an explanation offered as to why LF PECVD is capable of excellent surface passivation, comparable to remote-plasma results in literature and higher than previously published for LF PECVD. The achieved surface passivation quality is sufficient for dielectric rear-surface passivation without an underlying diffused back surface field. It is also shown that the purity grade of precursor gases used for film deposition can be lowered significantly without affecting cell efficiency and long-term stability on the module level, allowing for further cost reduction
Download or read book Surface Passivation of Crystalline Silicon by Amorphous Silicon Carbide Films for Photovoltaic Applications written by Rafel Ferré Tomàs and published by . This book was released on 2008 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Passivation of Crystalline Silicon Solar Cells by Amorphous Silicon Films written by Heiko Plagwitz and published by . This book was released on 2007 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Thin Films for Solar cell Applications written by RCA Laboratories and published by . This book was released on 1979 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Silicon Carbide Passivating Layers for Crystalline silicon based Heterojunction Solar Cells written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.
Download or read book Silicon surface passivation by plasma enhanced chemical vapor deposited amorphous silicon carbide films written by Isidro Martín García and published by . This book was released on 2003 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Silicon Compound Films for Surface Passivation and Antireflection Coating of Crystalline Silicon Solar Cells written by Roman Petres and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Silicon Carbide Solar Cells Fabricated Using ECR PECVD written by Vu Anh Vu and published by . This book was released on 2000 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report also studies the variation of these properties as functions of the growth conditions, such as substrate temperature, microwave power, chamber pressure, gas ratios, and doping levels. Then we applied the best growth conditions for making intrinsic and doped amorphous silicon carbide materials to produce good p-i-n solar cells. We found that a deposition pressure of 10 mTorr, a substrate temperatures of 300 to 350°C, and CH4/(CH4+SiH4) flows of 0.6 to 0.7 can produce very good amorphous silicon carbide solar cells. These solar cells have an open-circuit voltage of 0.96 V, and a fill factor of 0.71. We also found that our materials have superior quality compared to materials reported previously in the literature.
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 Surface Passivation of Crystalline Silicon by Dual Layer Amorphous Silicon Films written by Dmitri S. Stepanov and published by . This book was released on 2011 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Response Surface Methodology is used in this work to optimize the deposition conditions of SiNx. Optimization of the response surface function yielded deposition conditions that materialized in a surface recombination velocity of less than 4cm/s. The BACH (Back Amorphous Crystalline silicon Heterojunction) cell concept makes use of this dual layer a-Si:H/SiN x stack to form a high efficiency photovoltaic device. The high quality passivating structure can result in the BACH solar cell device with more than 20% conversion efficiency.The probability of recombination of photogenerated electron hole pairs in crystalline silicon is governed by the density of surface defect states and the density of charge carriers. Depositions of intrinsic hydrogenated amorphous silicon (a-Si:H) in dc saddle field (DCSF) PECVD system and hydrogenated amorphous silicon nitride (SiNx) in rf PECVD system forms a dual layer stack on c-Si, which results in an excellent passivation of the surface and an anti-reflection coating.
Download or read book Sputtered Aluminium Oxide and Amorphous Silicon for Silicon Solar Cells written by Xinyu Zhang and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-efficiency silicon solar cells have been attracting an increased interest in recent years. Surface passivation is essential for various types of high-performance solar cells, particularly when thinner silicon wafers are used to reduce the material cost. Passivating dielectric thin films have been widely studied and used in solar cells designs, these include atomic-layer deposited (ALD) aluminium oxide, plasma-enhanced chemical vapour deposited (PECVD) silicon nitride and PECVD intrinsic amorphous silicon. The aim of this thesis is to develop and optimise an alternative deposition method for surface passivating films: sputtering. Sputtering is especially attractive for industrial production, due to its high throughput, easy and safe operation and global cost-effectiveness. This thesis has focussed on optimising the reactive sputtering of aluminium oxide, using an aluminium target, and the non-reactive sputtering of amorphous silicon, using a silicon target. A key innovation has been the addition of hydrogen to the mix of gasses that form the plasma, which permits to incorporate hydrogen into the films, leading to a significantly improved surface passivation quality compared to non-hydrogenated films. We have achieved the best surface passivation results by sputtered aluminium oxide to date, with an effective surface recombination velocity of 1 cm/s on 1.5 ohm-cm n-type silicon. This result is similar to the SRV of 0.9 cm/s measured on aluminium oxide films deposited by PA-ALD on the same substrates. Good passivation was also achieved on p-type silicon. The investigations into the reactive sputtering process have shown that the film properties are closely related to the oxidation level of the aluminium target, which can be controlled by adjusting process parameters. It has also been found that the presence of hydrogen in the plasma is beneficial for establishing the optimum conditions of the deposition; not only does the surface passivation quality improve, but the reactive sputtering process becomes easier to control as well.We have also shown - for the first time - that intrinsic amorphous silicon (a-Si:H) films by sputtering deposition are capable of providing an excellent passivation of crystalline silicon surfaces. A SRV of 1.5 cm/s on 1.5 ohm-cm n-type silicon and SRV of 9 cm/s on 1 ohm-cm p-type silicon have been achieved, which are comparable to the commonly used PECVD deposited a-Si:H films. After investigating the film properties using Fourier Transform Infrared Spectroscopy (FTIR), we observe that our sputtered a-Si:H films have a characteristic signature in terms of chemical bonding configurations, where several types of silicon-hydrogen bonds exist. From those measurements we have estimated that there is approximately a 4% hydrogen concentration in the films, sufficient to achieve excellent surface passivation. Finally, the thesis also presents initial attempts at developing doped amorphous silicon films, which could enable the development of an all-sputtered silicon heterojunction solar cell technology. Lightly doped a-Si:H films were deposited using a 1% boron doped silicon target and a 0.01% phosphorus doped silicon target. We have found an appropriate way to avoid surface passivation degradation caused by the doped layer deposition onto an intrinsic a-Si:H layer.
Download or read book Amorphous and Microcrystalline Silicon Applied in Very Thin Tandem Solar Cells written by Sandra Schicho and published by Forschungszentrum Jülich. This book was released on 2011 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrogenated Amorphous Silicon Carbide Prepared Using DC Saddle Field PECVD for Photovoltaic Applications written by Cheng-Chieh Yang and published by . This book was released on 2011 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenated amorphous silicon carbide (a-SiC:H) can provide exceptional surface passivation essential for high-efficiency crystalline silicon solar cells. This thesis reports on the fundamental study of a-SiC:H films deposited using a novel deposition technique, DC saddle field PECVD, in contrast to the conventional industrial use of RF-PECVD. The growth conditions were optimized and correlated with passivating, structural, and optical characteristics. The lifetime has a strong dependency on deposition temperature and improves by over two orders of magnitude as the temperature increases; the maximum lifetime achieved in this work reached 0.5 ms. In addition, the Tauc optical gap can be increased from 1.7 eV to 2.3 eV by varying the precursor gas mixture ratio. Post-deposition annealing experiments demonstrate thermal stability of the samples deposited at 250 °C and in some instances shows improvement in passivation quality by a factor of two with a one-step annealing treatment at 300 °C for 15 minutes.
Download or read book Properties of Intrinsic and Co sputtered Hydrogenated Amorphous Silicon Films and Schottky Photovoltaic Devices written by Mark Gordon Thompson and published by . This book was released on 1980 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Amorphous Silicon Carbide for Photovoltaic Applications written by Stefan Janz and published by . This book was released on 2007 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt:
