Author: Nagarajan SridharPublisher:
ISBN:
Category :
Languages : en
Pages : 252
Book Description
Crystallization and Hydrogen Evolution Studies of Hydrogenated Amorphous Silicon Thick Films for Low Cost Solar Cells
High-rate growth of hydrogenated amorphous and microcrystalline silicon for thin-film silicon solar cells using dynamic very-high frequency plasma-enhanced chemical vapor deposition
Author: Thomas ZimmermannPublisher: Forschungszentrum Jülich
ISBN: 3893368922
Category :
Languages : en
Pages : 143
Book Description
Hydrogen Evolution and Crystallization in Hydrogenated Amorphous Silicon Films
Author: Nagarajan SridharHydrogen Evolution and Crystallization in Hydrogenated Amorphous Silicon Films
Author: Nagarajan SridharSilicon Heterojunction Solar Cells
Author: W.R. FahrnerPublisher: Trans Tech Publications Ltd
ISBN: 3038131024
Category : Technology & Engineering
Languages : en
Pages : 208
Book Description
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.
High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si, Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are reduced; (3) surface hydrogen removal--heavier and more energetic helium ions break the Si-H much easier than hydrogen ions. The preferential attachment of Si-H to Ge-H is reduced. They also found that with the small amount of hydrogen put into the plasma, the superior properties of a-(Si, Ge):H made from pure hydrogen dilution plasma were still maintained. These hydrogen ions help to remove the subsurface weakly bonded hydrogen and buried hydrogen. They also help to passivate the Ge-dangling bond.
Masters Theses in the Pure and Applied Sciences
Author: W. H. ShaferPublisher: Springer Science & Business Media
ISBN: 9780306447112
Category : Education
Languages : en
Pages : 410
Book Description
Volume 37 (thesis year 1992) reports a total of 12,549 thesis titles from 25 Canadian and 153 US universities (theses submitted in previous years but only now reported are indicated by the thesis year shown in parenthesis). The organization, like that of past years, consists of thesis titles arrange
High Growth Rate Deposition of Hydrogenated Amorphous Silicon-germanium Films and Devices Using ECR-PECVD
Author: Yong LiuPublisher:
ISBN:
Category :
Languages : en
Pages : 170
Book Description
Hydrogenated amorphous silicon germanium (a-SiGe:H) films and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, and quantum efficiency were characterized during the process of pursuing good materials. High-quality material was successfully fabricated with the ECR-PECVD technique at high growth rates. The device we made with 1.47 eV band gap has a fill factor of 64.5%. With the graded band gap and graded doping techniques, 70% fill factor was achieved when the band gap was graded from 1.75 to 1.47 eV. We also got 68% fill factor with the band gap graded form 1.75 to 1.38 eV.
Amorphous Silicon And Related Materials (In 2 Parts)
Author: Hellmut FritzschePublisher: World Scientific
ISBN: 981453191X
Category : Science
Languages : en
Pages : 1153
Book Description
This book presents the most recent important ideas and developments in the field of Hydrogenated Amorphous Silicon and related materials. Each contribution is authored by an outstanding expert in that particular area.
Amorphous and Nanocrystalline Silicon-Based Films - 2003: Volume 762
Author: Materials Research Society. MeetingPublisher:
ISBN:
Category : Science
Languages : en
Pages : 824
Book Description
Amorphous silicon technology has been the subject of symposia every year since 1984. This remarkable longevity is due to the continuous emergence of new scientific questions and new technological challenges for silicon thin films. Earlier there was a strong emphasis on methods to achieve high deposition rates using plasma or hot-wire chemical vapor deposition, and on the properties and applications of nanocrystalline silicon films, which for example have been incorporated into stacked a-Si:H/nc-Si:H solar cells. The papers appearing in this book are sorted under six chapter headings on the basis of subject matter. Chapter I is concerned with amorphous network structures, electronic metastability, defects, and photoluminescence. Chapter II focuses on thin-film transistors and imager arrays. Chapter III covers solar cells. Chapter IV addresses growth mechanisms, hot-filament CVD, and nc-Si:H growth. Chapter V contains all remaining topics in film growth, especially those related to devices. Finally, Chapter VI focuses on crystallized film.