Download or read book Semiconducting Aromatic Boron Carbide Films for Neutron Detection and Photovoltaic Applications written by Adeola O. Oyelade and published by . This book was released on 2019 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting aromatic-boron carbide composite/alloyed films formed by plasma enhanced chemical vapor deposition from carborane and aromatic precursors have been demonstrated to be excellent detectors for thermal neutrons because of the large 10B cross section. The electronic properties of these films derived from XPS show that the properties of boron carbide can be tuned by co-deposition of aromatic compounds and carborane. Aromatic doping results in narrower indirect band gaps (1.1 - 1.7 eV vs ̃3 eV for orthocarborane-derived boron carbide without aromatics) and average charge transport lifetimes (as long as 2.5 ms for benzene-orthocarborane and 1.5 - 2.5 ms for indole-orthocarborane) that are superior to those of boron carbide (35 μs). The films also show enhanced electron-hole separation that is also superior to those of boron carbide where the states at the top of the valence band is made of aromatic components while states at the bottom of the conduction band is a combination of aromatic and carborane moeities. These properties result in greatly enhanced (̃850%) charge collection, relative to films without aromatic content, in thermal neutron exposures at zero-bias, and are gamma-blind. Such films are therefore excellent candidates for zero-bias neutron detector applications. These properties also show little variation with increasing aromatic content beyond a critical concentration, indicating that at some point, excess aromatic results in the formation of regions of polymerized aromatic within the film, rather than in additional carborane/aromatic linkages. While previous studies on these aromatic-boron carbide materials indicate the potential for neutron detection due to the narrowed band gap, enhanced electron-hole separation and charge transport lifetimes compared to the boron carbide counterpart, the mechanisms of charge transport and photoconductivity (important for photovoltaic applications) of these materials have remained unexplored. Properties such as narrowed band gap, efficient electron-hole separation and long charge transport lifetimes, are also desirable in photovoltaic applications. This, plus ease of fabrication and environmental robustness makes aromatic-boron carbide films promising candidates for photovoltaic applications. Plasma enhanced chemical vapor deposition (PECVD) has been used to synthesize these aromatic-boron carbide composite films by co-deposition of pyridine, aniline or indole with orthocarborane/metacarborane. Film chemical composition and bonding were characterized by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), variable angle spectroscopic ellipsometry (VASE) and (in collaboration with Dowben Group at UNL) charge transport and photoconductivity measurements. Results show narrowed band gaps (indirect) where the top of the valence band is made up of the aromatic moiety and the conduction band minimum us made of aromatic and carborane moeities, improved charge carrier mobilities that is stoichiometry and frequency dependent (aniline-orthocarborane films). Photoconductivity measurement results obtained from ̃2.6:1 indole-orthocarborane film show fourth quadrant conductivity. I(V) curves indicate a photocurrent of 2.36 μA at zero bias, with an appreciable open-circuit voltage of 1V. The ability for these aromatic-boron carbide films to operate at zero bias for both neutron detection and photovoltaic applications is an excellent advantage that indicates low cost of operation of these materials.
Download or read book Optical Properties of Semiconducting Boron Carbide for Neutron Detection Applications written by Ravi B. Billa and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Semiconducting Boron Carbide written by Andrew D. Harken and published by . This book was released on 2002 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phase Evolution of Boron Nitride and Carbide during Chemical Vapor Deposition written by Sachin Sharma and published by Linköping University Electronic Press. This book was released on 2024-05-02 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin films of Boron Nitride (BN) and Boron Carbide (BC) possess properties that make them attractive for various applications. Epitaxially grown BN exhibits potential for optoelectronic devices, as piezoelectric materials, and graphene technology. Epitaxial BC is a semiconductor that could allow bandgap tuning and has potential applications in thermoelectric and optoelectronic devices. Both BN and BC material systems, generally deposited using chemical vapour deposition (CVD), are limited by the lack of control in depositing epitaxial films. In my thesis work, I have studied the evolution of various crystal phases of BN and BC and the factors that affect them during their CVD processes. I deposited and compared the growth of BN on Al2O3 (0001), (11 2 over bar 0), (1 1 over bar 02) and (10 1 over bar 0) substrates and used two organoboranes as boron precursors. Only Al2O3(11 2 over bar 0) and Al2O3 (0001) rendered crystalline films while the BN growth on the remaining substrates was X-ray amorphous. Furthermore, the less investigated Al2O3(11 2 over bar 0) had better crystalline quality versus the commonly used Al2O3 (0001). To further understand this, I studied crystalline BN thin films on an atomic scale and with a time evolution approach, uncovering the influence of carbon on hexagonal BN (h-BN). I showed that h-BN nucleates on both substrates but then either polytype transforms to rhombohedral-BN (r-BN) in stages, turns to less ordered turbostratic-BN or is terminated. An increase in local carbon content is the cause of these changes in epitaxial BN films during CVD. From the time evolution, we studied the effect of Al2O3 modification on h-BN nucleation during CVD. The interaction between boron and carbon during BN growth motivated studies also on the BxC materials. BxC was deposited using CVD at different temperatures on 4H-SiC(0001) (Si-face) and 4H-SiC(000 1 over bar) (C-face) substrates. Epitaxial rhombohedral-B4C (r-B4C) grew at 1300 °C on the C-face while the films deposited on the Si-face were polycrystalline. Comparing the initial nucleation layers on both 4H-SiC substrates on an atomic scale we showed that no interface phenomena are affecting epitaxial r-B4C growth conditions. We suggest that the difference in surface energy on the two substrate surfaces is the most plausible reason for the differences in epitaxial r-B4C growth conditions. In this thesis work, I identify the challenges and propose alternative routes to synthesise epitaxial BN and B4C materials using CVD. This fundamental materials science work enhances the understanding of growing these material systems epitaxially and in doing so furthers their development.
Download or read book Boron Carbide Films and Diodes written by Peter B. Welsch and published by . This book was released on 2002 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Semiconducting Boron Carbide Thin Films Structure Processing and Diode Applications written by Ruqiang Bao and published by . This book was released on 2010 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Novel Carborane Derived Semiconducting Thin Films for Neutron Detection and Device Applications written by Robinson James and published by . This book was released on 2015 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boron Carbide Devices for Neutron Detection Applications written by Ellen Edwina Day and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boron Rich Solids written by David Emin and published by AIP Conference Proceedings (Nu. This book was released on 1991 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1969 with total page 1502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Chemically Deposited Nanocrystalline Metal Oxide Thin Films written by Fabian I. Ezema and published by Springer Nature. This book was released on 2021-06-26 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book guides beginners in the areas of thin film preparation, characterization, and device making, while providing insight into these areas for experts. As chemically deposited metal oxides are currently gaining attention in development of devices such as solar cells, supercapacitors, batteries, sensors, etc., the book illustrates how the chemical deposition route is emerging as a relatively inexpensive, simple, and convenient solution for large area deposition. The advancement in the nanostructured materials for the development of devices is fully discussed.
Download or read book Evolution of Thin Film Morphology written by Matthew Pelliccione and published by Springer Science & Business Media. This book was released on 2008-01-29 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this book is on modeling and simulations used in research on the morphological evolution during film growth. The authors emphasize the detailed mathematical formulation of the problem. The book will enable readers themselves to set up a computational program to investigate specific topics of interest in thin film deposition. It will benefit those working in any discipline that requires an understanding of thin film growth processes.
Download or read book Handbook of Carbon Graphite Diamonds and Fullerenes written by Hugh O. Pierson and published by William Andrew. This book was released on 2012-12-02 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a review of the science and technology of the element carbon and its allotropes: graphite, diamond and the fullerenes. This field has expanded greatly in the last three decades stimulated by many major discoveries such as carbon fibers, low-pressure diamond, and the fullerenes. The need for such a book has been felt for some time. These carbon materials are very different in structure and properties. Some are very old (charcoal), others brand new (the fullerenes). They have different applications and markets and are produced by different segments of the industry.Few studies are available that attempt to review the entire field of carbon as a whole discipline. Moreover these studies were written several decades ago and a generally outdated since the development of the technology is moving very rapidly and scope of applications is constantly expanding and reaching into new fields such as aerospace, automotive, semiconductors, optics, and electronics. In this book the author provides a valuable, up-to-date account of both the newer and traditional forms of carbon, both naturally occurring and man-made. This volume will be a valuable resource for both specialists in, and occasional users of carbon materials.
Download or read book Two Dimensional Nanostructures written by Mahmood Aliofkhazraei and published by CRC Press. This book was released on 2012-05-02 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: After the 2010 Nobel Prize in Physics was awarded to Andre Geim and Konstantin Novoselov "for groundbreaking experiments regarding the two-dimensional material graphene," even more research and development efforts have been focused on two-dimensional nanostructures. Illustrating the importance of this area in future applications, Two-Dimensional Nanostructures covers the fabrication methods and properties of these materials. The authors begin with discussions on the properties, size effect, applications, classification groups, and growth of nanostructures. They then describe various characterization and fabrication methods, such as spectrometry, low-energy electron diffraction, physical and chemical vapor deposition, and molecular beam epitaxy. The remainder of the text focuses on mechanical, chemical, and physical properties and fabrication methods, including a new mechanical method for fabricating graphene layers and a model for relating the features and structures of nanostructured thin films. With companies already demonstrating the capabilities of graphene in a flexible touch-screen and a 150 GHz transistor, nanostructures are on their way to replacing silicon as the materials of choice in electronics and other areas. This book aids you in understanding the current chemical, mechanical, and physical processes for producing these "miracle materials."
Download or read book X Ray Diffraction by Polycrystalline Materials written by René Guinebretière and published by John Wiley & Sons. This book was released on 2013-03-01 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a physical approach to the diffraction phenomenon and its applications in materials science. An historical background to the discovery of X-ray diffraction is first outlined. Next, Part 1 gives a description of the physical phenomenon of X-ray diffraction on perfect and imperfect crystals. Part 2 then provides a detailed analysis of the instruments used for the characterization of powdered materials or thin films. The description of the processing of measured signals and their results is also covered, as are recent developments relating to quantitative microstructural analysis of powders or epitaxial thin films on the basis of X-ray diffraction. Given the comprehensive coverage offered by this title, anyone involved in the field of X-ray diffraction and its applications will find this of great use.
Download or read book Handbook of X ray Photoelectron Spectroscopy written by John F. Moulder and published by . This book was released on 1995 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Silicon written by Paul Siffert and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: With topics ranging from epitaxy through lattice defects and doping to quantum computation, this book provides a personalized survey of the development and use of silicon, the basis for the revolutionary changes in our lives sometimes called "The Silicon Age." Beginning with the very first developments more than 50 years ago, this reports on all aspects of silicon and silicon technology up to its use in exciting new technologies, including a glance at possible future developments.
