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Time Resolved Studies Of Electron And Hole Spin Dynamics In Modulation Doped Gaas Algaas Quantum Wells Elektronisk Resurs
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Book Synopsis Time-resolved Studies of Electron and Hole Spin Dynamics in Modulation-doped GaAs/AlGaAs Quantum Wells [Elektronisk Resurs] by : Tobias Korn
Download or read book Time-resolved Studies of Electron and Hole Spin Dynamics in Modulation-doped GaAs/AlGaAs Quantum Wells [Elektronisk Resurs] written by Tobias Korn and published by . This book was released on 2010 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin dynamics in semiconductors have gained much interest in the past years due to the emerging field of semiconductor spintronics. This review is focussed on the observation and control of electron and hole spin dynamics in modulation-doped heterostructures based on the GaAs/AlGaAs material system. Modulation doping allows for the creation of two-dimensional electron and hole systems with high carrier mobility. By confining carriers to a two-dimensional sheet, the spin-orbit interaction is modified significantly. In addition to this, it can be further modified by changing the symmetry of the system, for example by externally applied or built-in electric fields along the growth direction. Our recent experimental results on spin dynamics in two dimensions are reviewed and discussed in connection with theoretical considerations. A brief overview of the current research challenges in this field is given.
Book Synopsis Electrical Control of the Electron Spin Dynamics in [111]-oriented GaAs/AGaAs Quantum Wells by : Quang ha Duong
Download or read book Electrical Control of the Electron Spin Dynamics in [111]-oriented GaAs/AGaAs Quantum Wells written by Quang ha Duong and published by . This book was released on 2013 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have studied the electron spin dynamics in 111-oriented GaAs/AlGaAs quantum wells grown on 111-substrate by time-resolved photoluminescence spectroscopy. By applying an external electric field about 50 kV/cm along growth direction, we observed the spectacular increase of electron spin which can attain values greater than 30 ns. This phenomenon comes from the electrical control of spin-orbit interaction in conduction band that make the Rashba term compensate exactly with the Dresselhaus term. The cancellation effect of these two terms results in the suppression of electron spin relaxation induced by D'yakonov-Perelmechanism which is dominant in undoped quantum wells and at the temperatures greater than 50K. The measurement under an external transverse magnetic field (Voigt configuration) demonstrates that the spin relaxation times in three spatial directions are also controlled simultaneously by electric field. The "total" control of electron spin relaxation can only be observed in 111-oriented quantum wells. Finally, we also develop the model to interpret the experimental measurement of spin relaxation anisotropy depending on electric field in 111-oriented quantum wells.
Book Synopsis Electrons, Phonons and Their Interactions in Novel Modulation Doped GaAs/AlAs Based Quantum Wells by :
Download or read book Electrons, Phonons and Their Interactions in Novel Modulation Doped GaAs/AlAs Based Quantum Wells written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The lowest energy interband transitions in AlGaAs/AlAs quantum wells involve electrons localized in the AlAs x-valleys and holes confined in the AlGaAs layers. These transitions are indirect in both real as well as in kappa-space and are accompanied by strong replicas of the GaAs and AlAs phonons. When a magnetic field is applied perpendicular to the layers a large reduction in the recombination intensity is observed. This reduction is attributed to magnetic field induced localization of the carriers which results in a reduction of the electron-hole wavefunction overlap. We have also studied photoluminescence spectra from type-II, n-type, modulation doped GaAs/AlAs quantum wells due to radiative recombination of electrons localized in the AlAs x-valleys with holes confined in the GaAs layers. In the presence of a magnetic field the emission spectra exhibit features associated with transitions among the AlAs x-valley Landau levels and photo-injected holes. The slopes of these transitions yield an effective mass m = 0.44 for the electrons.
Book Synopsis Optical time resolved spin dynamics in III-V semiconductor quantum wells by : Matthew Anthony Brand
Download or read book Optical time resolved spin dynamics in III-V semiconductor quantum wells written by Matthew Anthony Brand and published by . This book was released on 2003 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Physics of Quantum Well Devices by : B.R. Nag
Download or read book Physics of Quantum Well Devices written by B.R. Nag and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum well devices have been the objects of intensive research during the last two decades. Some of the devices have matured into commercially useful products and form part of modern electronic circuits. Some others require further dev- opment, but have the promise of being useful commercially in the near future. Study of the devices is, therefore, gradually becoming compulsory for electronics specialists. The functioning of the devices, however, involve aspects of physics which are not dealt with in the available text books on the physics of semicond- tor devices. There is, therefore, a need for a book to cover all these aspects at an introductory level. The present book has been written with the aim of meeting this need. In fact, the book grew out of introductory lectures given by the author to graduate students and researchers interested in this rapidly developing area of electron devices. The book covers the subjects of heterostructure growth techniques, band-offset theory and experiments, electron states, electron-photon interaction and related phenomena, electron transport and the operation of electronic, opto-electronic and photonic quantum well devices. The theory as well as the practical aspects of the devices are discussed at length. The aim of the book is to provide a comprehensive treatment of the physics underlying the various devices. A reader after going through the book should find himself equipped to deal with all kinds of quantum well devices.
Book Synopsis Intersubband Transitions in Quantum Wells by : Emmanuel Rosencher
Download or read book Intersubband Transitions in Quantum Wells written by Emmanuel Rosencher and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the lectures delivered at the NATO Advanced Research Workshop on the "Intersubband Transistions in Quantum Wells" held in Cargese, France, between the t 9 h and the 14th of September 1991. The urge for this Workshop was justified by the impressive growth of work dealing with this subject during the last two or three years. Indeed, thanks to recent progresses of epitaxial growth techniques, such as Molecular Beam Epitaxy, it is now possible to realize semiconductor layers ( e.g. GaAs) with thicknesses controlled within one atomic layer, sandwiched between insulating layers (e.g. AlGaAs). When the semiconducting layer is very thin, i.e. less than 15 nm, the energy of the carriers corresponding to their motion perpendicular to these layers is quantized, forming subbands of allowed energies. Because of the low effective masses in these semiconducting materials, the oscillator strengths corresponding to intersubband transitions are extremely large and quantum optical effects become giant in the 5 - 20 ~ range: photoionization, optical nonlinearities, ... Moreover, a great theoretical surprise is that - thanks to the robustness of the effective mass theory - these quantum wells are a real life materialization of our old text book one-dimensional quantum well ideal. Complex physical phenomena may then be investigated on a simple model system.
Book Synopsis Quantum Wells: Physics And Electronics Of Two-dimensional Systems by : Alexander Shik
Download or read book Quantum Wells: Physics And Electronics Of Two-dimensional Systems written by Alexander Shik and published by World Scientific. This book was released on 1998-01-09 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This invaluable book is devoted to the physics, technology and device applications of semiconductor structures with ultrathin layers where the electronic properties are governed by the quantum-mechanical laws. Such structures called quantum wells or structures with the two-dimensional electron gas, have become one of the most actively investigated objects in modern solid state physics. Electronic properties of quantum wells differ dramatically from those of bulk semiconductors, which allows one to observe new types of physical phenomena, such as the quantum Hall effect and many other so-far-unknown kinetic and optical effects. This, in turn, offers wide opportunities for creating semiconductor devices based on new principles, and it has give birth to the new branch of electronics called nanoelectronics.
Book Synopsis Measurement of Electron-hole Friction in an N-doped GaAs/AlGaAs Quantum Well Using Optical Transient-grating Spectroscopy by :
Download or read book Measurement of Electron-hole Friction in an N-doped GaAs/AlGaAs Quantum Well Using Optical Transient-grating Spectroscopy written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We use phase-resolved transient grating spectroscopy to measure the drift and diffusion of electron-hole density waves in a semiconductor quantum well. The unique aspects of this optical probe allow us to determine the frictional force between a two-dimensional Fermi liquid of electrons and a dilute gas of holes. Knowledge of electron-hole friction enables prediction of ambipolar dynamics in high-mobility electron systems.
Book Synopsis Dynamics of Electrons at Intersubband Excitation in Asymmetric Tunnel-Coupled Quantum Well Structure by : E. A. Zibik
Download or read book Dynamics of Electrons at Intersubband Excitation in Asymmetric Tunnel-Coupled Quantum Well Structure written by E. A. Zibik and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present investigations of the intersubband electron dynamics in asymmetric tunnel-coupled GaAs/AlGaAs quantum wells. The study is performed by time resolved pump and probe experiments. Temporal evolution of the bleaching signals has biexponential behaviour. In addition to the time of the relaxation into the ground state with LO-phonon emission a second long decay time depending on transition energy and temperature is observed. We associate the second recovery time with transitions between confined F-state of quantum wells and states in the barriers including Xz-states which appear due to high content of Al. The influence of the transitions between subbands with energy separation less than optical phonon energy on the relaxation processes is also discussed.
Book Synopsis Spin Dynamics of Carriers in Doped GaAs Quantum-well Systems by : Jaswinder Singh Sandhu
Download or read book Spin Dynamics of Carriers in Doped GaAs Quantum-well Systems written by Jaswinder Singh Sandhu and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamical Kerr Effect in a Quantum-Well AlGaAs/GaAs Structure Under Circular Optical Excitation by : A. V. Kimel
Download or read book Dynamical Kerr Effect in a Quantum-Well AlGaAs/GaAs Structure Under Circular Optical Excitation written by A. V. Kimel and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-resolved magneto-optical Kerr effect is used for studying the ultrafast spin dynamics in a semiconductor heterostructure AlGaAs/GaAs in the subpicosecond time range. Results are analyzed on the basis of the semiconductor Bloch equations.
Book Synopsis Physics and Applications of Quantum Wells and Superlattices by : E.E. Mendez
Download or read book Physics and Applications of Quantum Wells and Superlattices written by E.E. Mendez and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the lectures delivered at the NATO Advanced Study Institute on "Physics and Applications of Quantum Wells and Superlattices", held in Erice, Italy, on April 21-May 1, 1987. This course was the fourth one of the International School of Solid-State Device Research, which is under the auspices of the Ettore Majorana Center for Scientific Culture. In the last ten years, we have seen an enormous increase in re search in the field of Semiconductor Heterostructures, as evidenced by the large percentage of papers presented in recent international conferences on semiconductor physics. Undoubtfully, this expansion has been made possible by dramatic advances in materials preparation, mostly by molecular beam epitaxy and organometallic chemical vapor deposition. The emphasis on epitaxial growth that was prevalent at the beginning of the decade (thus, the second course of the School, held in 1983, was devoted to Molecular Beam Epitaxy and Heterostructures) has given way to a strong interest in new physical phenomena and new material structures, and to practical applications that are already emerging from them.
Book Synopsis Large Increase of Electron Mobility in a Modulation-Doped AlGaAs/GaAs/AlGaAs Quantum Well with an Inserted Thin AlAs Barrier by : K. Pozela
Download or read book Large Increase of Electron Mobility in a Modulation-Doped AlGaAs/GaAs/AlGaAs Quantum Well with an Inserted Thin AlAs Barrier written by K. Pozela and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electron (polar optical (PO)) phonon scattering mechanisms which determine the electron mobility in a Al(0.25)Ga(0.75) As/GaAs/Al(0.25) Ga(0.75). As quantum well (QW) with an inserted thin AlAs barrier are considered. It is shown that the decrease of the second subband electron scattering by PO-phonon emission is responsible for the large increase of the mobility in the QW with the inserted barrier.
Book Synopsis The Dynamics and Spin Relaxation of Excitons in Gaas/Algaas Quantum Wells by : Aviv Frommer
Download or read book The Dynamics and Spin Relaxation of Excitons in Gaas/Algaas Quantum Wells written by Aviv Frommer and published by . This book was released on 1993 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electron transmission through non-tunneling regime of GaAs-AlGaAs Coupled Quantum Wells by : Sujaul Chowdhury
Download or read book Electron transmission through non-tunneling regime of GaAs-AlGaAs Coupled Quantum Wells written by Sujaul Chowdhury and published by GRIN Verlag. This book was released on 2017-09-17 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research Paper (postgraduate) from the year 2017 in the subject Physics - Quantum Physics, grade: 4.00, Shahjalal University of Science and Technology, course: Nanostructure Physics, language: English, abstract: We have investigated electron transmission through non-tunneling regime of a semiconductor nanostructure called Coupled Quantum Well (CQW). Oscillatory transmission coefficient as a function of energy is found to show spectacular waxing and waning in amplitude. Corresponding features are expected to be observed in optical (Physical Review B 54 (1996) 1541) and quantum transport (Physical Review Letters 58 (1987) 816) experiments and hence the results besides verifying the Physics will have impact on future devices based on CQW.
Book Synopsis Optically Probing Electron and Hole Spin Dynamics in Quantum Dots by : Stefan Schäck
Download or read book Optically Probing Electron and Hole Spin Dynamics in Quantum Dots written by Stefan Schäck and published by . This book was released on 2006 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Time-Resolved Electronic Relaxation Processes in Self-Organized Quantum Dots by :
Download or read book Time-Resolved Electronic Relaxation Processes in Self-Organized Quantum Dots written by and published by . This book was released on 2005 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have performed a comprehensive set of experiments on the dynamics of electrons and holes in semiconductor quantum dots, and a complete picture of the dynamics as a function of carrier density and temperature has emerged. Specifically, they have used two- and three-pulse femtosecond differential transmission spectroscopy to study the dependence of quantum dot carrier dynamics on temperature. At low temperatures and densities, the rates for relaxation between the quantum dot confined states and for capture from the barrier region into the various dot levels could be directly determined. For electron-hole pairs generated directly in the quantum dot excited state, relaxation is dominated by electron-hole scattering, and occurs on a 5-ps time scale. Capture times from the barrier into the quantum dot are on the order of 2 ps (into the excited state) and 10 ps (into the ground state). The phonon bottleneck was clearly observed in low-density capture experiments, and the conditions for its observation (namely, the suppression of electron-hole scattering for non-geminately captured electrons) were determined. As temperature increases beyond about 100 K, the dynamics become dominated by the reemission of carriers from the lower dot levels due to the large density of states in the wetting layer and barrier region. Measurements of the gain dynamics show fast (130-fs) gain recovery due to intradot carrier-carrier scattering, and picosecond-scale capture. Direct measurement of the transparency density versus temperature shows the dramatic effect of carrier reemission for the quantum dots to thermally activated scattering. The carrier dynamics at elevated temperatures are thus strongly dominated by the high density of the high-energy continuum states relative to the dot-confined levels. Deleterious hot carrier effects can be suppressed in quantum dot lasers by resonant tunneling injection.
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