Author: Darius Jamsheed Choksy Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Semiconductors have proven themselves to be an excellent platform for both the development of new technologies and the study of fundamental physics. Various semiconductor materials provide us the ability to control and study the bulk system behavior, electronic behavior, and light matter interactions. Of particular interest to this paper is the study of a quasi-particle that can form in semiconductors known as an exciton. Made from an electron and hole, it also has very useful photonic properties. In our work we study excitons created by photoexcitation, where a laser excites an electron from the lattice, creating an electron and hole, the electrons and holes created can then form a bound state known as an exciton. Excitons can transform into photons via radiative recombination. Our experiments typically deal with a system of quantum wells, engineered to keep the electrons and holes spatially separated, a bound pair of an electron and hole with the electron and hole in different quantum wells is known as an indirect exciton. Some of the properties of indirect excitons are an electric dipole moment, energy controlled by voltage, long lifetimes, macroscopic transport, and they are bosons. These properties as well as their interaction with light allow for systems to be created that act as proof-of-concept prototypes for excitonic devices, as well as a platform to study fundamental physics of cold bosons. The work in this dissertation is primarily focused on dipole-dipole attraction and the formation of a Fermi edge singularity in these systems. These works give us new insights into the interactions of bosons and formation of new states of matter.
Author: Matthew W. Hasling Publisher: ISBN: Category : Languages : en Pages : 62
Book Description
Indirect excitons are bosonic quasiparticles composed of an electron and a hole confined to spatially separated quantum wells. Many properties of excitons, such as their low effective mass, long lifetime, tunable energy, and optically active nature, make them an ideal system for studying condensed matter phenomena. This dissertation explores the transport properties associated with indirect excitons in various environments. In this dissertation, exciton transport is studied in multiple devices, created by carefully patterned electrodes, which create a varied potential energy landscape for the excitons. The first device is used to trap large amounts of excitons, which can be used to study the properties of dense exciton gases. The second device is used as a stirring potential for indirect excitons, and can give excitons angular momentum while they collect to the center of the device. In addition, a record high quality single quantum well structure is characterized, which may prove to be a new platform for studying indirect excitons. Measurements of this new sample show large transport and a record high diffusion coefficient for indirect excitons.
Author: Lewis H. Fowler-Gerace Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Spatially indirect excitons (IXs), also known as interlayer excitons, are bound pairs of an electron and a hole in spatially separated layers. IXs can propagate over long distances before they recombine into light, and they can cool down below the temperature of quantum degeneracy within their lifetimes, which can be controlled by gate voltage up to microseconds and beyond. These properties make IXs a promising platform for studying fundamental physics phenomena and as the medium for highly efficient signal processing devices. IXs were originally studied in gallium arsenide (GaAs) heterostructures, where IXs have shown evidence for Bose-Einstein condensation, and proof of principle has been demonstrated for excitonic transistors and excitonic integrated circuits. IXs only exist at low temperatures in GaAs systems due to the low IX binding energy on the order of 10 meV. In the transition-metal dichalcogenide (TMD) heterostructure system, the IX binding energy is predicted to be more than two orders of magnitude higher, making IXs stable at room temperature and allowing for the possibility of high temperature IX superfluidity. To date, observation of some of the key IX behaviors, namely the long-range IX transport and evidence of IX condensation, has remained elusive in the TMD system. This dissertation characterizes the IX spectrum in a MoSe2/WSe2 heterostructure, demonstrates the realization and control of long-range IX propagation using a new mechanism beyond the know mechanism for IX control in GaAs heterostructures, and separately identifies a quantum origin for the propagation of IXs generated by resonant excitation in the TMD heterostructure.
Author: Jason Leonard Publisher: Springer ISBN: 3319697331 Category : Technology & Engineering Languages : en Pages : 67
Book Description
This thesis presents results crucial to the emerging field of indirect excitons. These specially designed quasiparticles give the unique opportunity to study fundamental properties of quantum degenerate Bose gases in semiconductors. Furthermore, indirect excitons allow for the creation of novel optoelectronic devices where excitons are used in place of electrons. Excitonic devices are explored for the development of advanced signal processing seamlessly coupled with optical communication. The thesis presents and describes the author's imaging experiments that led to the discovery of spin transport of excitons. The many firsts presented herein include the first studies of an excitonic conveyer, leading to the discovery of the dynamical localization-delocalization transition for excitons, and the first excitonic ramp and excitonic diode with no energy-dissipating voltage gradient.
Author: Yuliya Yevgenyevna Kuznetsova Publisher: ISBN: 9781321451900 Category : Languages : en Pages : 67
Book Description
This dissertation explores studies of transport of indirect excitons (bosonic quasiparticles composed of bound pairs of an electron and a hole confined to spatially separated layers) in GaAs coupled quantum wells. The small mass and long lifetime of indirect excitons result in a relatively high quantum degeneracy temperature and efficient cooling, making indirect excitons a model system for studies of physics of cold bosons. In addition, indirect excitons are optically active, electronically controllable and have long enough lifetimes that their transport distances can be accommodated by lithography. These properties make indirect excitons a promising system for creating excitonic devices. The direction of the research presented in this dissertation is thus twofold: studying fundamental physics of excitons, including transport, thermalization, coherence, spin currents, and properties in high magnetic fields, and realization of optical excitonic devices, such as traps and transistors.
Author: Kikuo Cho Publisher: World Scientific ISBN: 9814491306 Category : Technology & Engineering Languages : en Pages : 496
Book Description
At Yamada Conference LIII, papers on many novel materials and on novel phenomena in condensed matter physics were presented — for instance, the achievement of simultaneous creation of excitons and free-electron-hole pairs in rare gas solids, and a low frequency fluctuation of the spectral shift of indirect excitons in GaAs coupled quantum wells. Single molecule spectroscopy is a powerful tool for studying molecules including biological systems; the study of delocalization of excitons in the photosynthetic light harvesting antenna system was also reported. The proceedings thus contain many excellent papers dealing with current research topics on the excitonic processes in bulk, quantum wells, quantum dots and other confined systems. This book will serve as an excellent source of recent references and reviews for a wide range of researchers in physics, chemistry, engineering and biological sciences.The proceedings have been selected for coverage in:• Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)
Author: Nick P Proukakis Publisher: World Scientific ISBN: 1908979704 Category : Science Languages : en Pages : 579
Book Description
The 1995 observation of Bose-Einstein condensation in dilute atomic vapours spawned the field of ultracold, degenerate quantum gases. Unprecedented developments in experimental design and precision control have led to quantum gases becoming the preferred playground for designer quantum many-body systems.This self-contained volume provides a broad overview of the principal theoretical techniques applied to non-equilibrium and finite temperature quantum gases. Covering Bose-Einstein condensates, degenerate Fermi gases, and the more recently realised exciton-polariton condensates, it fills a gap by linking between different methods with origins in condensed matter physics, quantum field theory, quantum optics, atomic physics, and statistical mechanics. Thematically organised chapters on different methodologies, contributed by key researchers using a unified notation, provide the first integrated view of the relative merits of individual approaches, aided by pertinent introductory chapters and the guidance of editorial notes.Both graduate students and established researchers wishing to understand the state of the art will greatly benefit from this comprehensive and up-to-date review of non-equilibrium and finite temperature techniques in the exciting and expanding field of quantum gases and liquids./a
Author: Alexei L. Ivanov Publisher: OUP Oxford ISBN: 019152882X Category : Science Languages : en Pages : 372
Book Description
This book is dedicated to Professor Leonid V Keldysh. His brilliant contributions to condensed matter physics include the Franz-Keldysh effect, an electron-hole liquid, the nonequilibrium (Keldysh) diagram technique, Bose-Einstein condensation (of excitons) and a ``metal-dielectric'' transition, acoustically-induced superlattices, multi-photon transitions and impact ionization in solids. In many respects, his work influenced and formed the paradigm of modern condensed matter physics. As a result, many famous researchers in the field have enthusiastically provided unique contributions to the book.
Author: Publisher: Elsevier ISBN: 0443193932 Category : Science Languages : en Pages : 270
Book Description
Semiconductors and Semimetals series, highlights new advances in the field, with this new volume presenting interesting chapters. Each chapter is written by an international board of authors. - Provides the latest information on cancer research - Offers outstanding and original reviews on a range of cancer research topics - Serves as an indispensable reference for researchers and students alike
Author: Darius Jamsheed Choksy
Author: Matthew W. Hasling
Author: Lewis H. Fowler-Gerace
Author: Jason Leonard
Author: Chih-Wei Eddy Lai
Author: Yuliya Yevgenyevna Kuznetsova
Author: Kikuo Cho
Author: Nick P Proukakis
Author: Alexei L. Ivanov
Author: