Author: Philipp KarzelPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Hydrogen Passivation and Phosphorous Gettering at Different Grain Boundary Types in Multicrystalline Silicon
Author: Philipp KarzelDependence of Phosphorus Gettering and Hydrogen Passivation Efficacy on Grain Boundary Type on Multicrystalline Silicon
Author: Philipp KarzelGrain Boundary Passivation of Multicrystalline Silicon Using Hydrogen Sulfide as a Sulfur Source
Author: Arunodoy SahaPublisher:
ISBN:
Category : Grain boundaries
Languages : en
Pages : 56
Book Description
Hydrogen sulfide (H2S) has been identified as a potential ingredient for grain boundary passivation of multicrystalline silicon. Sulfur is already established as a good surface passivation material for crystalline silicon (c-Si). Sulfur can be used both from solution and hydrogen sulfide gas. For multicrystalline silicon (mc-Si) solar cells, increasing efficiency is a major challenge because passivation of mc-Si wafers is more difficult due to its randomly orientated crystal grains and the principal source of recombination is contributed by the defects in the bulk of the wafer and surface. In this work, a new technique for grain boundary passivation for multicrystalline silicon using hydrogen sulfide has been developed which is accompanied by a compatible Aluminum oxide (Al2O3) surface passivation. Minority carrier lifetime measurement of the passivated samples has been performed and the analysis shows that success has been achieved in terms of passivation and compared to already existing hydrogen passivation, hydrogen sulfide passivation is actually better. Also the surface passivation by Al2O3 helps to increase the lifetime even more after post-annealing and this helps to attain stability for the bulk passivated samples. Minority carrier lifetime is directly related to the internal quantum efficiency of solar cells. Incorporation of this technique in making mc-Si solar cells is supposed to result in higher efficiency cells. Additional research is required in this field for the use of this technique in commercial solar cells.
Advanced Silicon & Semiconducting Silicon-Alloy Based Materials & Devices
Author: Jo NijsPublisher: CRC Press
ISBN: 1000445062
Category : Science
Languages : en
Pages : 488
Book Description
One of the first books to cover advanced silicon-based technologies, Advanced Silicon and Semiconducting Silicon Alloy-Based Materials and Devices presents important directions for research into silicon, its alloy-based semiconducting devices, and its development in commercial applications. The first section deals with single/mono crystalline silicon, focusing on the effects of heavy doping; the structure and electronic properties of defects and their impact on devices; the MBE of silicon, silicon alloys, and metals; CVD techniques for silicon and silicon germanium; the material properties of silicon germanium strained layers; silicon germanium heterojunction bipolar applications; FETs, IR detectors, and resonant tunneling devices in silicon, silicon germanium, and d-doped silicon; and the fascinating properties of crystalline silicon carbide and its applications. The second section explores polycrystalline silicon. It examines large grain polysilicon substrates for solar cells; the properties, analysis, and modeling of polysilicon TFTs; the technology of polysilicon TFTs in LCD displays; and the use of polycrystalline silicon and its alloys in VLSI applications. With contributors from leading academic and industrial research centers, this book provides wide coverage of fabrication techniques, material properties, and device applications.
Hydrogen in Semiconductors
Author: M. StutzmannPublisher: Elsevier
ISBN: 0444598839
Category : Science
Languages : en
Pages : 598
Book Description
Hydrogen on semiconductor surfaces has been an area of considerable activity over the last two decades. Structural, thermal, and dynamical properties of hydrogen chemisorbed on crystalline silicon and other semiconductors have been studied in great detail. These properties serve as a reference for related, but more complex systems such as hydrogen at multiple vacancies in crystalline semiconductors or at microvoids in amorphous samples. Interesting from a surface physics point of view is the fact that hydrogen as a monovalent element is an ideal terminator for unsaturated bonds on surfaces and therefore tends to have a large influence on surface reconstruction. A related phenomenon with large technological impact (for example in low cost solar cells) is the passivation of grain boundaries in microcrystalline semiconductors. Finally, hydrogenated semiconductor surfaces always appear as a boundary layer during low-energy hydrogenation of bulk semiconductors, so that a complete description of hydrogen uptake or desorption necessarily has to take these surfaces into account. This collection of invited and contributed papers has been carefully balanced to deal with amorphous and crystalline semiconductors and surfaces and presents basic and experimental work (basic and applied) as well as theory. The resulting volume presents a summary of the state-of-the-art in the field of hydrogen in semiconductors and will hopefully stimulate future work in this area.
Fundamental Studies of Grain Boundary Passivation in Polycrystalline Silicon with Application to Improved Photovoltaic Devices. A Final Research Report Covering Work Completed from February-December 1979
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Several aspects of the electrical properties of silicon grain boundaries have been studied. The temperature dependence of the zero-bias conductance and capacitance of single boundaries has been measured and shown to be in good agreement with a simple double depletion layer/thermal emission (DDL/TE) model developed to predict the transport properties of such structures. In addition, it has been shown that deconvolution of the I-V properties of some boundaries via a deconvolution scheme suggested by Pike and Seager yields effective one-electron densities of trapping states which are in good agreement with estimates obtained by low temperature electron emission measurements. Experiments have also been performed which indicate that diffusion of atomic hydrogen into silicon grain boundaries greatly reduces this density of trapping states. In properly prepared, large grained polycrystalline samples all measurable traces of grain boundary potential barriers can be removed to substantial penetration depths after several hours exposure to a hydrogen plasma at elevated temperatures. Initial experiments on prototype polysilicon solar cells have shown that this passivation process can improve AM1 efficiencies. In order to more fully understand and develop this process for improving practical multigrained cells, several device research efforts with other DOE/SERI funded contractors have been initiated.
Precipitation and Hydrogenation of Iron in Multicrystalline Silicon
Author: Anyao LiuPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This thesis studies the precipitation and the hydrogenation of dissolved iron in multicrystalline silicon (mc-Si). Photoluminescence imaging is used to obtain both the concentration and the spatial distribution of interstitial iron across mc-Si wafers, with an image resolution of 25 micrometres. In the first part, as-cut mc-Si wafers were examined in order to better understand the internal gettering of iron that occurs during the mc-Si ingot directional solidification process. A simple one-dimensional diffusion-capture model was developed to quantify the gettering process. Relaxation gettering by the grain boundaries was found to be present during ingot cooling, and results indicate that iron must have been super-saturated before the onset of precipitation. A systematic study of the precipitation kinetics of iron in mc-Si was then performed, with respect to the annealing temperature, time, iron super-saturation level, and different types and densities of precipitation sites in mc-Si. Annealing temperatures in the range of 400 - 700C (Celsius degree) were examined in detail. The precipitation of iron approximately follows an exponential decay, which is consistent with the classical Ham's precipitation model. However, the precipitation kinetics were found to demonstrate an increasing dependence on the level of the initial iron super-saturation as the super-saturation level decreases. A higher level of initial iron super-saturation was shown to result in a faster precipitation process. The degree of super-saturation only becomes irrelevant for a high level well above 1000. The dependence of the precipitation kinetics on the initial super-saturation level is likely related to the chemical energy required to initiate the precipitation process. Precipitation of iron was found to occur both at some of the grain boundaries and also at the intra-grain dislocations. The precipitation of iron, at temperatures where the dissolved iron is super-saturated, results in a significant reduction of the interstitial iron concentration by 1 - 2 orders of magnitude. However, the process is inefficient compared to the external gettering of iron via phosphorous diffusion. More importantly, annealing at elevated temperatures leads to a degradation of the mc-Si material quality, which offsets the benefit of the reduced dissolved iron concentration. The last section investigates the impact of hydrogen incorporation on the changes in the interstitial iron concentration and distribution in mc-Si wafers. Hydrogen was introduced into the silicon bulk by annealing wafers with plasma-enhanced chemical vapour deposited silicon nitride films, at 400 - 900C and for minutes to hours. Effective hydrogenation of the interstitial iron was observed. The concentration of interstitial iron was shown to reduce by more than 90% after a 30-minute anneal at 600 - 900C with silicon nitride films. The most effective hydrogenation of iron was found to take place at 700C, where more than 99% of iron was hydrogenated after 30 minutes. Results indicate that the observed reduction in interstitial iron concentration is not caused by an enhanced internal gettering of iron, as some authors suggested. The hydrogenation process is conjectured to be the pairing of positively charged iron with negatively charged hydrogen, forming less recombination active Fe-H complexes in silicon.
Proceedings of the Workshop on Materials Science and Physics of Non-Conventional Energy Sources
Author: Handbook of Photovoltaic Silicon
Author: Deren YangPublisher: Springer
ISBN: 9783662564714
Category : Technology & Engineering
Languages : en
Pages : 0
Book Description
The utilization of sun light is one of the hottest topics in sustainable energy research. To efficiently convert sun power into a reliable energy – electricity – for consumption and storage, silicon and its derivatives have been widely studied and applied in solar cell systems. This handbook covers the photovoltaics of silicon materials and devices, providing a comprehensive summary of the state of the art of photovoltaic silicon sciences and technologies. This work is divided into various areas including but not limited to fundamental principles, design methodologies, wafering techniques/fabrications, characterizations, applications, current research trends and challenges. It offers the most updated and self-explanatory reference to all levels of students and acts as a quick reference to the experts from the fields of chemistry, material science, physics, chemical engineering, electrical engineering, solar energy, etc..
Tenth E.C. Photovoltaic Solar Energy Conference
Author: A. LuquePublisher: Springer
ISBN: 940113622X
Category : Technology & Engineering
Languages : en
Pages : 1437
Book Description
I have great pleasure in presenting the Proceedings of the 10th European Photovoltaic Solar Energy Conference held in Lisbon from 8 to 12 April 1991. These Proceedings contain all the scientific papers delivered at the Conference. The following is a short summary of the Conference activities. The Conference was opened by the Minister of Industry and Energy of Portugal, Eng. Luis Mira do Amaral. At the opening ceremony the Becquerel Prize, created by the Commission of the European Communities, was awarded to Professor Werner Bloss of the University of Stuttgart, and presented by Professor Philippe Bourdeau, Director at the Directorate-General for Science, Research and Development. The Becquerellecture delivered by Professor Bloss constituted the scientific opening to the conference. About 760 delegates from 53 countries presented around 350 contributions, 50 of them as plenary lectures; the contributions were selected among the many papers submitted, this time more strictly than ever before. Also a selected group of scientists were invited to deliver 15 review lectures, to provide an adequate context to the contributions to the Conference. A Symposium on Photovoltaics in Developing Countries, which was very well attended, took place as a parallel event. The Symposium provided an opportunity to hear not only experts of the industrialized countries, but also speakers from the countries where photovoltaics provides services of paramount value.