Download or read book Optical Studies in Semiconductor Nanowires Optical and Magneto optical Properties of III V Nanowires written by Marta De Luca and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in III V Semiconductor Nanowires and Nanodevices written by Jianye Li and published by Bentham Science Publishers. This book was released on 2011-09-09 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Semiconductor nanowires exhibit novel electronic and optical properties due to their unique one-dimensional structure and quantum confinement effects. In particular, III-V semiconductor nanowires have been of great scientific and technological interest fo"

Download or read book Magnetooptical properties of dilute nitride nanowires written by Mattias Jansson and published by Linköping University Electronic Press. This book was released on 2020-06-18 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured III-V semiconductors have emerged as one of the most promising materials systems for future optoelectronic applications. While planar III-V compounds are already at the center of the ongoing lighting revolution, where older light sources are replaced by modern white light LEDs, fabricating such materials in novel architectures, such as nanowires and quantum dots, creates new possibilities for optoelectronic applications. Not only do nanoscale structures allow the optically active III-V materials to be integrated with silicon microelectronics, but they also give rise to new fascinating properties inherent to the nanoscale. One of the key parameters considered when selecting materials for applications in light-emitting and photovoltaic devices is the band gap energy. While alloying of conventional III-V materials provides a certain degree of band gap tunability, a significantly enhanced possibility of band gap engineering is offered by so-called dilute nitrides, where incorporation of a small percentage of nitrogen into III-V compounds causes a dramatic down-shift of the conduction band edge. In addition, nitrogen-induced splitting of the conduction band in dilute nitrides can be utilized in intermediate band solar cells, belonging to the next generation of photovoltaic devices. For any material to be viable for optoelectronic applications, detailed knowledge of the electronic structure of the material, as well as a good understanding of carrier recombination processes is vital. For example, alloying may not only cause changes in the electronic structure but can also induce disorder. Disorder-induced potential fluctuations may alter charge carrier and exciton dynamics, and may even induce quantum confinement. Moreover, various defects in the material may introduce detrimental non-radiative (NR) states in the band gap deteriorating radiative efficiency. It is evident that, due to their different growth mechanisms, such properties could be markedly different in nanowires as compared to their planar counterparts. In this thesis, I aim to describe the electronic structure of dilute nitride nanowires, and its effects on the optical properties. Firstly, we investigate the electronic structure, and the structural and optical properties of novel GaNAsP nanowires, with a particular focus on the dominant recombination channels in the material. Secondly, we show how short-range fluctuations in the nitrogen content lead to the formation of quantum dots in dilute nitride nanowires, and investigate their electronic structure. Finally, we investigate the combined charge carrier and exciton dynamics of the quantum dots and effects of defects in their surroundings. Before considering individual sources of NR recombination, it is instructive to investigate the overall effects of nitrogen incorporation on the structural properties of the nanowires. In Paper I, we show that nitrogen incorporation up to 0.16% in Ga(N)AsP nanowires does not affect the overall structural quality of the material, nor does nitrogen degrade the good compositional uniformity of the nanowires. It is evident from our studies, however, that nitrogen incorporation has a strong and complex effect on recombination processes. We first show that nitrogen incorporation in GaNAsP nanowires reduces the NR recombination at room temperature as compared to the nitrogen-free nanowires (Paper I). This is in stark contrast to dilute nitride epilayers, where nitrogen incorporation enhances NR recombination. The reason for this difference is that in nanowires the surface recombination, rather than recombination via point defects, is the dominant NR recombination mechanism. We suggest that the nitrogen-induced suppression of the NR surface recombination in the nanowires is due to nitridation of the nanowire surface. Another NR recombination channel common in III-V nanowires is caused by the presence of structural defects, such as rotational twin planes and stacking faults. Interestingly, while nitrogen incorporation does not appear to affect the density of such structural defects, increasing nitrogen incorporation reduces the NR recombination via the structural defects (Paper II). This is explained by competing trapping of excited carriers/excitons to the localized states characteristic to dilute nitrides, and at nitrogen-induced NR defects. This effect is, however, only present at cryogenic temperatures, while at room temperature the NR recombination via the structural defects is not the dominant recombination channel. Importance of point defects in carrier recombination is highlighted in Paper III. Using the optically detected magnetic resonance technique, we show that gallium vacancies (VGa) that are formed within the nanowire volume act as efficient NR recombination centers, degrading optical efficiency of the Ga(N)AsP-based nanowires. Interestingly, while the defect formation is promoted by nitrogen incorporation, it is also readily present in ternary GaAsP nanowires. This contrasts with previous studies on planar structures, where VGa was not formed in the absence of nitrogen, unless subjected to irradiation by high-energy particles or heavy n-type doping. This, again, highlights how the defect formation is strikingly different in nanowires as compared to planar structures, likely due to the different growth processes. Potential fluctuations in the conduction band, caused by non-uniformity of the nitrogen incorporation, is characteristic to dilute nitrides and is known to cause exciton/carrier localization. We find that in dilute nitride nanowires, such fluctuations at the short range cause three-dimensional quantum confinement of excitons, resulting in optically active quantum dots with spectrally ultranarrow and highly polarized emission lines (Paper IV). A careful investigation of such quantum dots reveals that their properties are strongly dependent on the host material (Papers V, VI). While the principal quantization axis of the quantum dots formed in the ternary GaNAs nanowires is preferably oriented along the nanowire axis (Paper V), it switches to the direction perpendicular to the nanowire axis in the quaternary GaNAsP nanowires (Paper VI). Another aspect illustrating the influence of the host material on the quantum-dot properties is the electronic character of the captured hole. In both alloys, we show coexistence of quantum dots where the captured holes are of either a pure heavy-hole character or a mixed light-hole and heavy-hole character. In the GaNAs quantum dots, the main cause of the light- and heavy-hole splitting is uniaxial tensile strain induced by a combination of lattice mismatch with the nanowire core and local alloy fluctuations (Paper V). In the GaNAsP quantum dots, however, we suggest that the main mechanism for the light- and heavy-hole splitting is local fluctuations in the P/As ratio (Paper VI). Using time correlation single-photon counting, we show that the quantum dots in these dilute nitride nanowires behave as single photon emitters (Paper VI), confirming the three-dimensional quantum confinement of the emitters. Finally, since the quantum dots are formed by fluctuations mainly in the conduction band, only electrons are preferentially captured in the 0D confinement potential, whereas holes are expected to be mainly localized through the Coulomb interaction once an electron is captured by the quantum dot. In Paper VII, we investigate this rather peculiar capture mechanism, which we show to lead to unipolar, negative charging of the quantum dot. Moreover, we demonstrate that carrier capture by some quantum dots is strongly affected by the presence of defects in their local surroundings, which further alters the charge state of the quantum dot, where formation of the negatively charged exciton is promoted at the expense of its neutral counterpart. This underlines that the local surroundings of the quantum dots may greatly affect their properties and illustrates a possible way to exploit the defects for charge engineering of the quantum dots. In summary, in this thesis work, we identify several important non-radiative recombination processes in dilute nitride nanowires that can undermine the potential of these novel nanostructures for future optoelectronic applications. The gained knowledge could be found useful for designing strategies to mitigate these harmful processes, thereby improving the efficiency of future light-emitting and photovoltaic devices based on these nanowires. Furthermore, we uncover a set of optically bright quantum dot single-photon emitters embedded in the dilute nitride nanowires, and reveal their unusual electronic structure with strikingly different confinement potentials between electrons and holes. Our findings open a new pathway for charge engineering of the quantum dots in nanowires, attractive for applications in e.g. quantum computation and optical switching.

Download or read book Novel Compound Semiconductor Nanowires written by Fumitaro Ishikawa and published by CRC Press. This book was released on 2017-10-17 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: One dimensional electronic materials are expected to be key components owing to their potential applications in nanoscale electronics, optics, energy storage, and biology. Besides, compound semiconductors have been greatly developed as epitaxial growth crystal materials. Molecular beam and metalorganic vapor phase epitaxy approaches are representative techniques achieving 0D–2D quantum well, wire, and dot semiconductor III-V heterostructures with precise structural accuracy with atomic resolution. Based on the background of those epitaxial techniques, high-quality, single-crystalline III-V heterostructures have been achieved. III-V Nanowires have been proposed for the next generation of nanoscale optical and electrical devices such as nanowire light emitting diodes, lasers, photovoltaics, and transistors. Key issues for the realization of those devices involve the superior mobility and optical properties of III-V materials (i.e., nitride-, phosphide-, and arsenide-related heterostructure systems). Further, the developed epitaxial growth technique enables electronic carrier control through the formation of quantum structures and precise doping, which can be introduced into the nanowire system. The growth can extend the functions of the material systems through the introduction of elements with large miscibility gap, or, alternatively, by the formation of hybrid heterostructures between semiconductors and another material systems. This book reviews recent progresses of such novel III-V semiconductor nanowires, covering a wide range of aspects from the epitaxial growth to the device applications. Prospects of such advanced 1D structures for nanoscience and nanotechnology are also discussed.

Download or read book Investigation of the Optical and Mechanical Properties of III V Semiconductor Nanowires written by John Bradley and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wide Band Gap Semiconductor Nanowires 2 written by Vincent Consonni and published by John Wiley & Sons. This book was released on 2014-08-08 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, the second of two volumes, describes heterostructures and optoelectronic devices made from GaN and ZnO nanowires. Over the last decade, the number of publications on GaN and ZnO nanowires has grown exponentially, in particular for their potential optical applications in LEDs, lasers, UV detectors or solar cells. So far, such applications are still in their infancy, which we analyze as being mostly due to a lack of understanding and control of the growth of nanowires and related heterostructures. Furthermore, dealing with two different but related semiconductors such as ZnO and GaN, but also with different chemical and physical synthesis methods, will bring valuable comparisons in order to gain a general approach for the growth of wide band gap nanowires applied to optical devices.

Download or read book Optical Properties of Semiconductor Nanowires written by Gerald Brönstrup and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Semiconductor Nanowires I Growth and Theory written by and published by Academic Press. This book was released on 2015-11-26 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor Nanowires: Part A, Number 93 in the Semiconductor and Semimetals series, focuses on semiconductor nanowires. Contains comments from leading contributors in the field semiconductor nanowires Provides reviews of the most important recent literature Presents a broad view, including an examination of semiconductor nanowires Comprises up to date advancements in the technological development of nanowire devices and systems, and is comprehensive enough to be used as a reference book on nanowires as well as a graduate student text book

Download or read book BREAD written by Cesare Manetti and published by Sapienza Università Editrice. This book was released on 2017-05-01 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bread contains human knowledge: from knowledge concerning fertility of the land to farming methods harvesting, and seed processing, not to mention the different possibilities of consumption of cereals and the different ways in which they are cooked. In bread, we find all those components: the transformation of the natural landscape, technological and economic development which over the centuries have led to the building of a social organization, with a precise division and distribution of tasks and roles.

Download or read book Optical Properties of III V Nanowires and Their Application for Charge Transport and Single photon Emission written by Michael Møller and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Properties of III V Nanowires and Their Application for Charge Transport and Single photon Emission written by and published by . This book was released on 2012 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamental Properties of Semiconductor Nanowires written by Naoki Fukata and published by Springer Nature. This book was released on 2020-11-16 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers virtually all aspects of semiconductor nanowires, from growth to related applications, in detail. First, it addresses nanowires’ growth mechanism, one of the most important topics at the forefront of nanowire research. The focus then shifts to surface functionalization: nanowires have a high surface-to-volume ratio and thus are well-suited to surface modification, which effectively functionalizes them. The book also discusses the latest advances in the study of impurity doping, a crucial process in nanowires. In addition, considerable attention is paid to characterization techniques such as nanoscale and in situ methods, which are indispensable for understanding the novel properties of nanowires. Theoretical calculations are also essential to understanding nanowires’ characteristics, particularly those that derive directly from their special nature as one-dimensional nanoscale structures. In closing, the book considers future applications of nanowire structures in devices such as FETs and lasers.

Download or read book Semiconductor Nanowires written by J Arbiol and published by Elsevier. This book was released on 2015-03-31 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanowires promise to provide the building blocks for a new generation of nanoscale electronic and optoelectronic devices. Semiconductor Nanowires: Materials, Synthesis, Characterization and Applications covers advanced materials for nanowires, the growth and synthesis of semiconductor nanowires—including methods such as solution growth, MOVPE, MBE, and self-organization. Characterizing the properties of semiconductor nanowires is covered in chapters describing studies using TEM, SPM, and Raman scattering. Applications of semiconductor nanowires are discussed in chapters focusing on solar cells, battery electrodes, sensors, optoelectronics and biology. Explores a selection of advanced materials for semiconductor nanowires Outlines key techniques for the property assessment and characterization of semiconductor nanowires Covers a broad range of applications across a number of fields

Download or read book Optical properties of single semiconductor nanowires and nanowire ensembles written by Carsten Pfüller and published by . This book was released on 2011 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Present and Future of Jus Cogens written by Enzo Cannizzaro and published by Sapienza Università Editrice. This book was released on 2015-12-31 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the contributions presented to the first edition of the Gaetano Morelli Lectures, held in the Spring of 2014 on “the Present and Future of Jus Cogens”. The first two Chapters reproduce the two general courses by Christian Tomuschat and by Pierre-Marie Dupuy. Two short Chapters, by Enzo Cannizzaro and by Beatrice Bonafé, address topics dealt with in the final seminar class.

Download or read book Semiconductor Nanowires II Properties and Applications written by and published by Academic Press. This book was released on 2016-01-11 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor Nanowires: Part B, and Volume 94 in the Semiconductor and Semimetals series, focuses on semiconductor nanowires. Includes experts contributors who review the most important recent literature Contains a broad view, including examination of semiconductor nanowires

Download or read book Wide Band Gap Semiconductor Nanowires 1 written by Vincent Consonni and published by John Wiley & Sons. This book was released on 2014-08-08 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: GaN and ZnO nanowires can by grown using a wide variety of methods from physical vapor deposition to wet chemistry for optical devices. This book starts by presenting the similarities and differences between GaN and ZnO materials, as well as the assets and current limitations of nanowires for their use in optical devices, including feasibility and perspectives. It then focuses on the nucleation and growth mechanisms of ZnO and GaN nanowires, grown by various chemical and physical methods. Finally, it describes the formation of nanowire heterostructures applied to optical devices.