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Author: Jianhua Zhu Publisher: ISBN: Category : Languages : en Pages : 124
Book Description
High quality [mu]c-SiGe:H is a very promising alternative for high efficiency photovoltaic device. The preparation of this material requires very high hydrogen dilution ratio in PECVD system. The deposition rate was greatly limited by this high hydrogen ratio. In this work, ECR PECVD technique is used to deposit [mu]c-SiGe:H material. The growth rate can be greatly enhanced by taking advantage of the high plasma density and low ion energy features of ECR and extremely high hydrogen dilution ratios are no longer necessary for [mu]c-SiGe:H growth. Films with good crystallinity were prepared at hydrogen dilution ratio as low as 1:15. An intensive study has been completed for the [mu]c-SiGe:H with 0 to over 75% Ge incorporated. The optical bandgap shrinks with the incorporation of Ge into the material. Raman spectra and the increase of activation energy and photosensitivity indicates the deterioration of crystallinity by adding Ge to the Si structure. Solar cell devices using [mu]c-SiGe:H as the active layer were deposited on stainless steel substrates. Fill factors over 55% were achieved for [mu]c-SiGe devices with less than 35% Ge. An [mu]c-Si buffer layer between n+ and[mu]c-SiGe:H n layer was used in the device design and this buffer layer revealed to be very beneficial to the device performance and the growth rate of [mu]c-SiGe:H active layer. C-V measurements showed that the accidental oxygen leakage can raise the doping level to the order of 1E17cm−3. ppm level TMB can be mixed in the source gas to very effectively reduce the N-type doping brought by oxygen. Short circuit current was increased by the TMB counter doping. The minority carrier diffusion length was estimated from reversed bias QE and C-V measurements. In the [mu]c-SiGe:H devices fabricated by ECR PECVD, the hole diffusion length is several tenth micrometers. The accidental doping in the [mu]c-SiGe:H deteriorates the device performance by decreasing the minority carrier diffusion length. Compensating doping of TMB can increase minority carrier diffusion length L[subscript p] and improve short circuit current, and hence improve the conversion efficiency of solar cell device.
Author: Jianhua Zhu Publisher: ISBN: Category : Languages : en Pages : 124
Book Description
High quality [mu]c-SiGe:H is a very promising alternative for high efficiency photovoltaic device. The preparation of this material requires very high hydrogen dilution ratio in PECVD system. The deposition rate was greatly limited by this high hydrogen ratio. In this work, ECR PECVD technique is used to deposit [mu]c-SiGe:H material. The growth rate can be greatly enhanced by taking advantage of the high plasma density and low ion energy features of ECR and extremely high hydrogen dilution ratios are no longer necessary for [mu]c-SiGe:H growth. Films with good crystallinity were prepared at hydrogen dilution ratio as low as 1:15. An intensive study has been completed for the [mu]c-SiGe:H with 0 to over 75% Ge incorporated. The optical bandgap shrinks with the incorporation of Ge into the material. Raman spectra and the increase of activation energy and photosensitivity indicates the deterioration of crystallinity by adding Ge to the Si structure. Solar cell devices using [mu]c-SiGe:H as the active layer were deposited on stainless steel substrates. Fill factors over 55% were achieved for [mu]c-SiGe devices with less than 35% Ge. An [mu]c-Si buffer layer between n+ and[mu]c-SiGe:H n layer was used in the device design and this buffer layer revealed to be very beneficial to the device performance and the growth rate of [mu]c-SiGe:H active layer. C-V measurements showed that the accidental oxygen leakage can raise the doping level to the order of 1E17cm−3. ppm level TMB can be mixed in the source gas to very effectively reduce the N-type doping brought by oxygen. Short circuit current was increased by the TMB counter doping. The minority carrier diffusion length was estimated from reversed bias QE and C-V measurements. In the [mu]c-SiGe:H devices fabricated by ECR PECVD, the hole diffusion length is several tenth micrometers. The accidental doping in the [mu]c-SiGe:H deteriorates the device performance by decreasing the minority carrier diffusion length. Compensating doping of TMB can increase minority carrier diffusion length L[subscript p] and improve short circuit current, and hence improve the conversion efficiency of solar cell device.
Author: Xuejun Niu Publisher: ISBN: Category : Languages : en Pages : 180
Book Description
Germanium, with its almost direct gap band structure, is an attractive material for photovoltaic applications. Carbon is added to the germanium lattice to increase the band gap. Since germanium and carbon are not soluble in equilibrium, only a metastable process can be used for growth. In this research, we used a remote, low pressure electron cyclotron resonance plasma enhanced chemical vapor deposition system (ECR-PECVD) to deposit nanocrystalline Ge and Ge[subscript l -x]C[subscript x] films. Nanocrystalline germanium:H films were grown on glass and stainless steel substrates from a mixture of germane and hydrogen. X-ray diffraction spectra revealed a predominant 220 orientation in the films. Raman spectra showed a sharp peak at 300 cm−1. The grain size in the films could be controlled by hydrogen dilution during growth, with higher dilutions leading to a smaller grain size. Grain size varied between 15 nm and 74 nm. Hall measurements showed that as-grown films were always n type, with carrier concentrations in the 1016/cm3 range. The mobility of electrons was shown to increase with increasing grain size, with the highest mobility being 5.4 cm2/V-sec at 300 K. Mobility and carrier concentration both increased with increasing temperature, the latter observation implying that there is a distribution of deep states in the material. p+nn+ devices were made with nanocrystalline germanium base layer and they showed significant increase in short-circuit current compared to nanocrystalline silicon devices. This is attributed to the higher absorption of the material down to the infrared region as shown by the quantum efficiency (QE) measurement. Defect density measured by C-V measurement was in the 1017 cm−3 range. Diffusion length was measured using QE vs voltage techniques and was estimated to be [Difference]0.5 [Mu]m. To add C into the lattice CH4 or C2H4 gas was added to the stock gas mixture. Absorption curve shifts to higher energy with higher C content. Incorporation of C atoms into the Ge lattice was shown to noticeably degrade the material on both mobility and crystallinity. However device performance is still reasonable and the QE curve shifts to higher energy, thus showing the photovoltaic potential of the material.
Author: Jef Poortmans Publisher: John Wiley & Sons ISBN: 0470091266 Category : Science Languages : en Pages : 504
Book Description
Thin-film solar cells are either emerging or about to emerge from the research laboratory to become commercially available devices finding practical various applications. Currently no textbook outlining the basic theoretical background, methods of fabrication and applications currently exist. Thus, this book aims to present for the first time an in-depth overview of this topic covering a broad range of thin-film solar cell technologies including both organic and inorganic materials, presented in a systematic fashion, by the scientific leaders in the respective domains. It covers a broad range of related topics, from physical principles to design, fabrication, characterization, and applications of novel photovoltaic devices.
Author: S.D. Brotherton Publisher: Springer Science & Business Media ISBN: 3319000020 Category : Technology & Engineering Languages : en Pages : 467
Book Description
Introduction to Thin Film Transistors reviews the operation, application and technology of the main classes of thin film transistor (TFT) of current interest for large area electronics. The TFT materials covered include hydrogenated amorphous silicon (a-Si:H), poly-crystalline silicon (poly-Si), transparent amorphous oxide semiconductors (AOS), and organic semiconductors. The large scale manufacturing of a-Si:H TFTs forms the basis of the active matrix flat panel display industry. Poly-Si TFTs facilitate the integration of electronic circuits into portable active matrix liquid crystal displays, and are increasingly used in active matrix organic light emitting diode (AMOLED) displays for smart phones. The recently developed AOS TFTs are seen as an alternative option to poly-Si and a-Si:H for AMOLED TV and large AMLCD TV applications, respectively. The organic TFTs are regarded as a cost effective route into flexible electronics. As well as treating the highly divergent preparation and properties of these materials, the physics of the devices fabricated from them is also covered, with emphasis on performance features such as carrier mobility limitations, leakage currents and instability mechanisms. The thin film transistors implemented with these materials are the conventional, insulated gate field effect transistors, and a further chapter describes a new thin film transistor structure: the source gated transistor, SGT. The driving force behind much of the development of TFTs has been their application to AMLCDs, and there is a chapter dealing with the operation of these displays, as well as of AMOLED and electrophoretic displays. A discussion of TFT and pixel layout issues is also included. For students and new-comers to the field, introductory chapters deal with basic semiconductor surface physics, and with classical MOSFET operation. These topics are handled analytically, so that the underlying device physics is clearly revealed. These treatments are then used as a reference point, from which the impact of additional band-gap states on TFT behaviour can be readily appreciated. This reference book, covering all the major TFT technologies, will be of interest to a wide range of scientists and engineers in the large area electronics industry. It will also be a broad introduction for research students and other scientists entering the field, as well as providing an accessible and comprehensive overview for undergraduate and postgraduate teaching programmes.
Author: Joseph M. Marshall Publisher: Springer Science & Business Media ISBN: 9401006326 Category : Technology & Engineering Languages : en Pages : 361
Book Description
The primary objective of this NATO Advanced Study Institute (ASI) was to present an up-to-date overview of various current areas of interest in the field of photovoltaic and related photoactive materials. This is a wide-ranging subject area, of significant commercial and environmental interest, and involves major contributions from the disciplines of physics, chemistry, materials, electrical and instrumentation engineering, commercial realisation etc. Therefore, we sought to adopt an inter disciplinary approach, bringing together recognised experts in the various fields while retaining a level of treatment accessible to those active in specific individual areas of research and development. The lecture programme commenced with overviews of the present relevance and historical development of the subject area, plus an introduction to various underlying physical principles of importance to the materials and devices to be addressed in later lectures. Building upon this, the ASI then progressed to more detailed aspects of the subject area. We were also fortunately able to obtain a contribution from Thierry Langlois d'Estaintot of the European Commission Directorate, describing present and future EC support for activities in this field. In addition, poster sessions were held throughout the meeting, to allow participants to present and discuss their current activities. These were supported by what proved to be very effective feedback sessions (special thanks to Martin Stutzmann), prior to which groups of participants enthusiastically met (often in the bar) to identify and agree topics of common interest.
Author: Pietro Mandracci Publisher: BoD – Books on Demand ISBN: 9535124455 Category : Technology & Engineering Languages : en Pages : 186
Book Description
The structural properties of materials play a fundamental role in the determination of their suitability for a specific application. This book is intended as a contribution to the efforts to increase the knowledge of the influence exerted on the properties of materials by their crystalline or amorphous structure. To this aim, some of the materials that are most promising for their use in different technological fields have been studied, namely graphene, titanium oxide, several types of functional metal oxides, porphyrinic crystalline solids, plasma deposited polymers, amorphous silicon, as well as hydrogenated amorphous carbon. These materials have been presented by the authors for their use in different applications, including microelectronics, photonics, and biomedicine.
Author: Antonio Luque Publisher: John Wiley & Sons ISBN: 0470721693 Category : Technology & Engineering Languages : en Pages : 1172
Book Description
The most comprehensive, authoritative and widely cited reference on photovoltaic solar energy Fully revised and updated, the Handbook of Photovoltaic Science and Engineering, Second Edition incorporates the substantial technological advances and research developments in photovoltaics since its previous release. All topics relating to the photovoltaic (PV) industry are discussed with contributions by distinguished international experts in the field. Significant new coverage includes: three completely new chapters and six chapters with new authors device structures, processing, and manufacturing options for the three major thin film PV technologies high performance approaches for multijunction, concentrator, and space applications new types of organic polymer and dye-sensitized solar cells economic analysis of various policy options to stimulate PV growth including effect of public and private investment Detailed treatment covers: scientific basis of the photovoltaic effect and solar cell operation the production of solar silicon and of silicon-based solar cells and modules how choice of semiconductor materials and their production influence costs and performance making measurements on solar cells and modules and how to relate results under standardised test conditions to real outdoor performance photovoltaic system installation and operation of components such as inverters and batteries. architectural applications of building-integrated PV Each chapter is structured to be partially accessible to beginners while providing detailed information of the physics and technology for experts. Encompassing a review of past work and the fundamentals in solar electric science, this is a leading reference and invaluable resource for all practitioners, consultants, researchers and students in the PV industry.
Author: Jianhua Zhu
Author: Jianhua Zhu![Growth and Properties of Nanocrystalline Ge and Ge1-[subscript X]C[subscript X] Films and Photovoltaic Devices PDF](https://books.google.com/books/content/images/frontcover/HKbpNwAACAAJ?fife=w80-h100)
Author: Xuejun Niu
Author: Iowa State University
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Author: Jef Poortmans
Author: S.D. Brotherton
Author: Joseph M. Marshall
Author: Pietro Mandracci
Author: Antonio Luque