Author: Eric G. Barbagiovanni
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
In nanostructures (NSs), to acquire a fundamental understanding of the electronic states by studying the optical properties is inherently complicated. A widely used simplification to this problem comes about by developing a model for a small scale representation of types of NSs and applying it to a hierarchy of fabrication methods. However, this methodology fails to account for structural differences incurred by the fabrication method that lead to differences in the optical properties. Proper modelling is realized by first considering the proper range of experimental parameters individually as inputs to a theoretical model and applying the correct parameters to the corresponding fabrication method. This thesis studies the connection between the structural and optical properties of NSs as a function of the fabrication method, using, principally, x-ray photoemission, Rutherford backscattering, photoluminesence, and Raman spectroscopy. Ion implanted Si and Ge quantum dots (QDs) in dielectric matrix were prepared to study the optical and structural properties, and compared against several other preparation methods. Ge QDs are known to exhibit a high concentration of defect states. The cause of these states was studied for QDs in a sapphire matrix and attributed to diffusion and desorption of Ge during annealing. Optical studies of Si QDs fabricated using an implantation mask revealed that state-filling and excitation transfer are important parameters in densely packed QD arrays. Structural analysis of Si QDs in silica revealed a well defined interface composed of Si$_2$O$_3$ and no stress was detected. Furthermore, the valence level was pinned at its bulk position possibly due to interface states. This information was used to refine our theoretical model of QDs and then compared with a range of crystalline and amorphous Si and Ge NSs. Stronger confinement effects were observed in amorphous Si and Ge NSs, possibly due to the nature of the interface or re-normalization of the effective mass as a function of NS size. These results establish a framework for proper parameter control in theoretical modelling.
Author: Arjun Mandal
Publisher: Springer
ISBN: 9811043345
Category : Technology & Engineering
Languages : en
Pages : 84
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Book Description
This book looks at the effects of ion implantation as an effective post-growth technique to improve the material properties, and ultimately, the device performance of In(Ga)As/GaAs quantum dot (QD) heterostructures. Over the past two decades, In(Ga)As/GaAs-based QD heterostructures have marked their superiority, particularly for application in lasers and photodetectors. Several in-situ and ex-situ techniques that improve material quality and device performance have already been reported. These techniques are necessary to maintain dot density and dot size uniformity in QD heterostructures and also to improve the material quality of heterostructures by removing defects from the system. While rapid thermal annealing, pulsed laser annealing and the hydrogen passivation technique have been popular as post-growth methods, ion implantation had not been explored largely as a post-growth method for improving the material properties of In(Ga)As/GaAs QD heterostructures. This work attempts to remedy this gap in the literature. The work also looks at introduction of a capping layer of quaternary alloy InAlGaAs over these In(Ga)As/GaAs QDs to achieve better QD characteristics. The contents of this volume will prove useful to researchers and professionals involved in the study of QDs and QD-based devices.
Author: Ladislaus Alexander Banyai
Publisher: World Scientific
ISBN: 9814504238
Category : Science
Languages : en
Pages : 264
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Book Description
Semiconductor Quantum Dots presents an overview of the background and recent developments in the rapidly growing field of ultrasmall semiconductor microcrystallites, in which the carrier confinement is sufficiently strong to allow only quantized states of the electrons and holes. The main emphasis of this book is the theoretical analysis of the confinement induced modifications of the optical and electronic properties of quantum dots in comparison with extended materials. The book develops the theoretical background material for the analysis of carrier quantum-confinement effects, introduces the different confinement regimes for relative or center-of-mass motion quantization of the electron-hole-pairs, and gives an overview of the best approximation schemes for each regime. A detailed discussion of the carrier states in quantum dots is presented and surface polarization instabilities are analyzed, leading to the self-trapping of carriers near the surface of the dots. The influence of spin-orbit coupling on the quantum-confined carrier states is discussed. The linear and nonlinear optical properties of small and large quantum dots are studied in detail and the influence of the quantum-dot size distribution in many realistic samples is outlined. Phonons in quantum dots as well as the influence of external electric or magnetic fields are also discussed. Last but not least the recent developments dealing with regular systems of quantum dots are also reviewed. All things included, this is an important piece of work on semiconductor quantum dots not to be dismissed by serious researchers and physicists.
Author: Saumya Sengupta
Publisher: Springer
ISBN: 9811057028
Category : Technology & Engineering
Languages : en
Pages : 77
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Book Description
This book explores the effects of growth pause or ripening time on the properties of quantum dots(QDs). It covers the effects of post-growth rapid thermal annealing (RTA) treatment on properties of single layer QDs. The effects of post-growth rapid thermal annealing (RTA) treatment on properties of single layer QDs are discussed. The book offers insight into InAs/GaAs bilayer QD heterostructures with very thin spacer layers and discusses minimum spacer thickness required to grow electronically coupled bilayer QD heterostructures. These techniques make bilayer QD heterostructures a better choice over the single layer and uncoupled multilayer QD heterostructure. Finally, the book discusses sub-monolayer (SML) growth technique to grow QDs. This recent technique has been proven to improve the device performance significantly. The contents of this monograph will prove useful to researchers and professionals alike.
Author: Xin Tong
Publisher: Springer Nature
ISBN: 3030742709
Category : Technology & Engineering
Languages : en
Pages : 319
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Book Description
This book presents a comprehensive overview of state-of-the-art quantum dot photodetectors, including device fabrication technologies, optical engineering/manipulation strategies, and emerging photodetectors with building blocks of novel quantum dots (e.g. perovskite) as well as their hybrid structured (e.g. 0D/2D) materials. Semiconductor quantum dots have attracted much attention due to their unique quantum confinement effect, which allows for the facile tuning of optical properties that are promising for next-generation optoelectronic applications. Among these remarkable properties are large absorption coefficient, high photosensitivity, and tunable optical spectrum from ultraviolet/visible to infrared region, all of which are very attractive and favorable for photodetection applications. The book covers both fundamental and frontier research in order to stimulate readers' interests in developing novel ideas for semiconductor photodetectors at the center of future developments in materials science, nanofabrication technology and device commercialization. The book provides a knowledge sharing platform and can be used as a reference for researchers working in the fields of photonics, materials science, and nanodevices.
Author: Dieter Bimberg
Publisher: John Wiley & Sons
ISBN: 9780471973881
Category : Science
Languages : en
Pages : 350
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Book Description
Da die Nachfrage nach immer schnelleren und kleineren Halbleiterbauelementen stetig wächst, sind Quanten-Dots und -Pyramiden rasant in den Mittelpunkt der Halbleiterforschung gerückt. Dieses Buch vermittelt einen umfassenden Überblick über den aktuellen Forschungsstand auf diesem Gebiet. Behandelt werden u.a. Fragen, wie Strukturen aufgebaut, wie sie charakterisiert werden und wie sie die Leistungsfähigkeit der Bauelemente bestimmen. (11/98)
Author: Aleksey Andreev
Publisher: World Scientific Publishing Company Incorporated
ISBN: 9789812568816
Category : Technology & Engineering
Languages : en
Pages : 400
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Book Description
Semiconductor structures containing zero-dimensional objects — quantum dots — are the subject of intensive research worldwide. This monograph describes a detailed theory of the electronic band structure and optical properties of semiconductor quantum dots.The author provides a comprehensive description of an original approach based on a combination of the Fourier transform, the Green's function and plane-wave expansion techniques in the framework of multiband 8x8 kp theory. The calculated band structure, optical properties and device applications are analyzed in line with available experiments for a large number of realistic quantum dot structures and various combinations of materials, such as InGaN, GaN/AlN, ZnSe, InGaAs (including dots-in-the-well), ZnSe/CdSe, and lead salts.
Author: Elena Borovitskaya
Publisher: World Scientific
ISBN: 9814488798
Category : Technology & Engineering
Languages : en
Pages : 214
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Book Description
In this book, leading experts on quantum dot theory and technology provide comprehensive reviews of all aspects of quantum dot systems. The following topics are covered: (1) energy states in quantum dots, including the effects of strain and many-body effects; (2) self-assembly and self-ordering of quantum dots in semiconductor systems; (3) growth, structures, and optical properties of III-nitride quantum dots; (4) quantum dot lasers.
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 782
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Book Description
Author: Inamuddin
Publisher: Materials Research Forum LLC
ISBN: 1644901250
Category : Technology & Engineering
Languages : en
Pages : 360
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Book Description
The book provides a thorough survey of current research in quantum dots synthesis, properties, and applications. The unique properties of these new nanomaterials offer multifunctional applications in such fields as photovoltaics, light-emitting diodes, field-effect transistors, lasers, photodetectors, solar cells, biomedical diagnostics and quantum computing. Keywords: Quantum Dots (QD), Photovoltaics, Light-emitting Diodes, Field-effect Transistors, Lasers, Photodetectors, Solar Cells, Biomedical Diagnostics, Quantum Computing, QD Synthesis, Carbon QDs, Graphene QDs, QD Sensors, Supercapacitors, Magnetic Quantum Dots, Cellular/Molecular Separation, Chromatographic Separation Column, Photostability, Luminescence of Carbon QDs, QD Materials for Water Treatment, Semiconductor Quantum Dots, QD Drug Delivery, Antibacterial Quantum Dots.
