Download or read book Growth and Characterization of Self assembled Quantum Dots for Intermediate Band Solar Cells written by Meng Sun and published by . This book was released on 2013 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, Molecular Beam Epitaxy technology is presented in detail and several powerful characterization techniques such as XRD, AFM, TEM, PL are also reviewed. SAQDs are discussed to be applied in IBSCs application due to the formation of intermediate band which helps to absorb sub-band gap photons. We investigate how the structural and optical properties of InAs self-assembled quantum dots buried in AlAs0.56Sb0.44 barriers can be controlled through the use of thin GaAs1xSbx cladding layers. Structural and optical properties of the SAQDs are studied, and the characteristics we demonstrate for this quantum dot system show great potential for application in intermediate band solar cells.
Download or read book Self Assembled Quantum Dots written by Zhiming M Wang and published by Springer Science & Business Media. This book was released on 2007-11-29 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multidisciplinary book provides up-to-date coverage of carrier and spin dynamics and energy transfer and structural interaction among nanostructures. Coverage also includes current device applications such as quantum dot lasers and detectors, as well as future applications to quantum information processing. The book will serve as a reference for anyone working with or planning to work with quantum dots.
Download or read book The Role of Quantum Dot Size on the Performance of Intermediate Band Solar Cells written by Najla A. Alnami and published by . This book was released on 2014 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this thesis is to understand possible mechanisms for the reported decrease of the open circuit voltage and solar cell efficiency in quantum dot (QD) intermediate band solar cells (IBSCs). More specifically, the effect of indium arsenide (InAs) QD height on the open circuit voltage and solar cell efficiency was studied in a systematic way. To explore this effect in QD solar cells, several solar cells (SCs) were grown with varying InAs QD heights. All experimental characteristics of the QD solar cells were compared to a reference structure without QDs. All samples were grown by Molecular Beam Epitaxy (MBE), and self-assembled InAs QDs were formed using the Stranski-Krastanov (SK) growth method. Using a QD truncation technique, the height of the QDs was accurately varied between 2 nm and 5 nm, while maintaining both lateral size and areal density of the QDs. The intermediate band (IB) of each solar cell was constructed from 10 layers of InAs QDs of the same size and density. All samples were fabricated as solar cell devices using standard optical photolithography, for electrical characterization and solar cell efficiency studies. Optical and structural characterization was done for all samples. The following characterizations were performed: Transmission Electron Microscopy (TEM), Low Temperature Photoluminescence (PL), Power Dependent PL, External Quantum Efficiency (EQE), Temperature Dependent Solar Power Conversion Efficiency, and Current-Voltage measurements. The efficiency measurements demonstrate the critical role of QD size on the performance of QD IBSCs. The EQE measurement indicates a change in the position of the band edge, due to carrier confinement, consistent with a QD size variation as verified by TEM and PL. Measurements demonstrate that the EQE in the NIR range of the spectrum is enhanced in the QD IBSCs devices due to light absorption by the QDs. This work also demonstrates that open circuit voltage (Voc) decreases with an increase of the QD height, which leads to significant degradation of the solar cell conversion efficiency for QD sizes above 3 nm. In addition, for samples with QD heights of 4 nm and above, the EQE spectra in the GaAs region decreases, indicating a loss of photocurrent, most likely due to traps introduced by the large QDs. These experimental results suggest that the open circuit voltage in QD IBSCs degrades with the increase of QD height as a result of (i) a decrease of the effective band gap of the absorber media and (ii) enhanced Shockley-Read-Hall recombination in the presence of traps in the solar cell space charge region.
Download or read book Epitaxial Growth and Real Time Characterization of Self assembled Quantum Dots Using Reflection High Energy Electron Diffraction written by Chandani P.K. Rajapaksha and published by . This book was released on 2010 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Self Assembled Quantum Dots written by Zhiming M. Wang and published by Springer. This book was released on 2008-11-01 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: This multidisciplinary book provides up-to-date coverage of carrier and spin dynamics and energy transfer and structural interaction among nanostructures. Coverage also includes current device applications such as quantum dot lasers and detectors, as well as future applications to quantum information processing. The book will serve as a reference for anyone working with or planning to work with quantum dots.
Download or read book Quantum Dot Intermediate Band Solar Cells written by Steven Evans Jenks and published by . This book was released on 2012 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advisor: Robert Gilmore.
Download or read book Growth and Spectroscopic Characterization of Self assembled Lateral Quantum Dot Molecules written by Lijuan Wang and published by . This book was released on 2009 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Growth Characterization and Intermixing of Self assembled InAs InP Quantum Dot Structures written by Satyanarayan Barik and published by . This book was released on 2007 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Dot Solar Cells written by Jiang Wu and published by Springer Science & Business Media. This book was released on 2013-09-28 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of various quantum dot solar cell designs, including quantum dot intermediate band solar cells, hot electron quantum dot solar cells, quantum-dot sensitized solar cells, colloidal quantum dot solar cells, hybrid polymer-quantum dot solar cells, and MEG quantum dot solar cells. Both theoretical and experimental approaches are described. Quantum Dot Solar Cells helps to connect the fundamental laws of physics and the chemistry of materials with advances in device design and performance. The book can be recommended for a broad audience of chemists, electrical engineers, and materials scientists, and is suitable for use in courses on materials and device design for advanced and future optoelectronics.
Download or read book Quantum Dots written by Ameenah Al-Ahmadi and published by BoD – Books on Demand. This book was released on 2012-04-04 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book “Quantum dots: A variety of a new applications” provides some collections of practical applications of quantum dots. This book is divided into four sections. In section 1 a review of the thermo-optical characterization of CdSe/ZnS core-shell nanocrystal solutions was performed. The Thermal Lens (TL) technique was used, and the thermal self-phase Modulation (TSPM) technique was adopted as the simplest alternative method. Section 2 includes five chapters where novel optical and lasing application are discussed. In section 3 four examples of quantum dot system for different applications in electronics are given. Section 4 provides three examples of using quantum dot system for biological applications. This is a collaborative book sharing and providing fundamental research such as the one conducted in Physics, Chemistry, Biology, Material Science, Medicine with a base text that could serve as a reference in research by presenting up-to-date research work on the field of quantum dot systems.
Download or read book Quantum Dot Enhanced Epitaxial Lift off Solar Cells written by Mitchell F. Bennett and published by . This book was released on 2013 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Embedded nanostructures such as quantum dots (QDs) have been studied for many applications in solar cells including enhanced mini-band absorption in intermediate-band solar cells and current matching in multi junction cells. The major drawbacks of using such techniques to decrease intrinsic solar cell loss mechanisms are twofold: first, it is difficult to maintain partially populated states using QDs due to a quick thermal extraction of carriers; second, QDs have a weak absorption which necessitates a near-perfect control of QD growth mechanisms to carefully ensure a balance between dot size and density. One avenue for improving absorption into QDs is to utilize a thin cell with a back surface reflector in order to increase the effective optical path length (OPL) of light through the QD region, which has the potential to increase absorption into QD states. One method for the processing of thin solar cells that has been experimentally demonstrated on large 4-6" wafers is epitaxial lift-off, which takes advantage of an inverted growth and a wet chemical etch of a sacrificial release layer to remove the substrate. In this thesis, 0.25 cm2 InAs/GaAs QD cells were grown on 4" wafers, fabricated, and processed by epitaxial lift off, creating thin and flexible devices. Materials and optical characterization techniques such as atomic force microscopy and photoluminescence were used on test structures prior to and following ELO, and analysis indicated that QD optical coherence and material quality after ELO processing were preserved, although non-uniform. This was concluded to be caused by the radial thermal profile of the growth reactor, through which spatial dependence led to local variations in QD quality and size across the 4" wafer, indicative of the high temperature sensitivity of QDs. Transmission electron microscopy measurements were used to investigate defects and dislocations throughout the QD device structure that would impact performance, and showed a higher concentration of defects in regions of the wafer subject to a higher temperature during growth. A similar pattern of radial dependence was observed in solar cell devices by electrical characterization. Current-voltage measurements under one-sun AM0 illumination were taken on several cells around the wafer, showing a statistical variation in solar cell device metrics dependent on wafer position. Spectral responsivity measurements show an established cavity mode pattern in sub-host bandgap wavelengths, which is discussed as an enhancement due to the thinning of the device. Integrated external quantum efficiency shows a QD contribution to the short circuit current density of 0.23 mA/cm2. In addition to optical, materials, and electrical characterization, QD and baseline ELO devices were exposed to alpha radiation to gauge the effects of a harmful environment on cell performance. The QD device exhibited a remaining factor increase of 2 % (absolute) in conversion efficiency over the baseline device at an end of life alpha particle fluence of 5x109[alpha]/cm2/s. In addition, linear temperature coefficients for solar cell figures of merit were extracted as a function of increasing [alpha] fluence. At a fluence of 5x108[alpha]/cm2/s, the QD device showed an efficiency temperature coefficient 0.2 %/°C higher (absolute) than the baseline, indicating that the inclusion of QDs could improve the radiation and temperature tolerance of solar cell devices used for space applications."--Abstract.
Download or read book Colloidal Quantum Dot Optoelectronics and Photovoltaics written by Gerasimos Konstantatos and published by Cambridge University Press. This book was released on 2013-11-07 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Captures the most up-to-date research in the field, written in an accessible style by the world's leading experts.
Download or read book Self Assembled InGaAs GaAs Quantum Dots written by and published by Academic Press. This book was released on 1999-03-29 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is concerned with the crystal growth, optical properties, and optical device application of the self-formed quantum dot, which is one of the major current subjects in the semiconductor research field.The atom-like density of states in quantum dots is expected to drastically improve semiconductor laser performance, and to develop new optical devices. However, since the first theoretical prediction for its great possibilities was presented in 1982, due to the difficulty of their fabrication process. Recently, the advent of self-organized quantum dots has made it possible to apply the results in important optical devices, and further progress is expected in the near future.The authors, working for Fujitsu Laboratories, are leading this quantum-dot research field. In this volume, they describe the state of the art in the entire field, with particular emphasis on practical applications.
Download or read book VLSI Micro and Nanophotonics written by El-Hang Lee and published by CRC Press. This book was released on 2018-09-03 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Addressing the growing demand for larger capacity in information technology, VLSI Micro- and Nanophotonics: Science, Technology, and Applications explores issues of science and technology of micro/nano-scale photonics and integration for broad-scale and chip-scale Very Large Scale Integration photonics. This book is a game-changer in the sense that it is quite possibly the first to focus on "VLSI Photonics". Very little effort has been made to develop integration technologies for micro/nanoscale photonic devices and applications, so this reference is an important and necessary early-stage perspective on this field. New demand for VLSI photonics brings into play various technological and scientific issues, as well as evolutionary and revolutionary challenges—all of which are discussed in this book. These include topics such as miniaturization, interconnection, and integration of photonic devices at micron, submicron, and nanometer scales. With its "disruptive creativity" and unparalleled coverage of the photonics revolution in information technology, this book should greatly impact the future of micro/nano-photonics and IT as a whole. It offers a comprehensive overview of the science and engineering of micro/nanophotonics and photonic integration. Many books on micro/nanophotonics focus on understanding the properties of individual devices and their related characteristics. However, this book offers a full perspective from the point of view of integration, covering all aspects of benefits and advantages of VLSI-scale photonic integration—the key technical concept in developing a platform to make individual devices and components useful and practical for various applications.
Download or read book Quantum Dot Molecules written by Jiang Wu and published by Springer Science & Business Media. This book was released on 2013-10-28 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantum dot molecule (QDM) is composed of two or more closely spaced quantum dots or “artificial atoms.” In recent years, QDMs have received much attention as an emerging new artificial quantum system. The interesting and unique coupling and energy transfer processes between the “artificial atoms” could substantially extend the range of possible applications of quantum nanostructures. This book reviews recent advances in the exciting and rapidly growing field of QDMs via contributions from some of the most prominent researchers in this scientific community. The book explores many interesting topics such as the epitaxial growth of QDMs, spectroscopic characterization, and QDM transistors, and bridges between the fundamental physics of novel materials and device applications for future information technology. Both theoretical and experimental approaches are considered. Quantum Dot Molecules can be recommended for electrical engineering and materials science department courses on the science and design of advanced and future electronic and optoelectronic devices.
Download or read book Next Generation Photovoltaics written by A. Martí and published by CRC Press. This book was released on 2003-09-01 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although photovoltaics are regarded by many as the most likely candidate for long term sustainable energy production, their implementation has been restricted by the high costs involved. Nevertheless, the theoretical limit on photovoltaic energy conversion efficiency-above 85%-suggests that there is room for substantial improvement of current comme
Download or read book Bismuth Containing Alloys and Nanostructures written by Shumin Wang and published by Springer. This book was released on 2019-07-03 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on novel bismuth-containing alloys and nanostructures, covering a wide range of materials from semiconductors, topological insulators, silica optical fibers and to multiferroic materials. It provides a timely overview of bismuth alloys and nanostructures, from material synthesis and physical properties to device applications and also includes the latest research findings. Bismuth is considered to be a sustainable and environmentally friendly element, and has received increasing attention in a variety of innovative research areas in recent years. The book is intended as a reference resource and textbook for graduate students and researchers working in these fields.
