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Dynamics Of Electrons At Intersubband Excitation In Asymmetric Tunnel Coupled Quantum Well Structure
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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 Quantum Well Intersubband Transition Physics and Devices by : Hui C. Liu
Download or read book Quantum Well Intersubband Transition Physics and Devices written by Hui C. Liu and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intersubband transitions in quantum wells have attracted tremendous attention in recent years, mainly due to the promise of applications in the mid and far-infrared regions (2--20 mum). Many of the papers presented in Quantum Well Intersubband Transition Physics and Devices are on the basic linear intersubband transition processes, detector physics and detector application, reflecting the current state of understanding and detector applications, where highly uniform, large focal plane arrays have been demonstrated. Other areas are still in their early stages, including infrared modulation, harmonic generation and emission.
Book Synopsis Kinetics of Intersubband Optical Excitation and Photoinduced Electron Transfer in an Asymmetric Double Quantum Well by :
Download or read book Kinetics of Intersubband Optical Excitation and Photoinduced Electron Transfer in an Asymmetric Double Quantum Well written by and published by . This book was released on 1992 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical excitation of electrons in an asymmetric double quantum well is theoretically examined. The well is biased to align the excited levels and permit resonant electron tunneling. Emphasis is made on the photoinduced transfer of electrons counter to the bias electric field force. Systems with a weak polarization relaxation (dephasing), are studied using the conventional technique of the Schrodinger equation. A density matrix approach is developed to describe optical excitations in the presence of an arbitrary dephasing. Quantum beats, which follow a short-pulse excitation of the double well, are shown to crucially depend on the dephasing. The excitation profiles obtained for cases of different dephasing reveal the full range of tunneling coupling between the wells from completely coherent to incoherent (stepwise).
Book Synopsis Intersubband Transitions in Quantum Wells: Physics and Devices by : Sheng S. Li
Download or read book Intersubband Transitions in Quantum Wells: Physics and Devices written by Sheng S. Li and published by Springer. This book was released on 1998-07-31 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of Intersubband Transitions in Quantum Wells: Physics and Devices is to facilitate the presentation and discussion of the recent results in theoretical, experimental, and applied aspects of intersubband transitions in quantum wells and dots. This reference work is based on the International Workshop that was held at National Cheng Kung University in Tainan, Taiwan in December 15-18, 1997. Intersubband transitions in quantum wells and quantum dots have attracted considerable attention in recent years, mainly due to the promise of various applications in the mid- and far-infrared regions (2-30 mum). Over 40 invited and contributed papers were presented in this four-day workshop, with topics covering most aspects of the intersubband transition phenomena including: the basic intersubband transition process, multiquantum well infrared photodetector (QWIP) physics, large format (640×480) GaAs QWIP (with 9.0 mum cutoff) focal plane arrays (FPAs) for IR imaging camera applications, infrared modulation, intersubband emission including mid- and long-wavelength quantum cascade (QC) lasers such as short (lambda = 3.4 mum) and long (lambda = 11.5 mum) wavelength room temperature QC lasers, quantum fountain intersubband laser at 15.5 mum wavelength in GaAs/AIGaAs quantum well, harmonic generation and nonlinear effects, ultra-fast phenomena such as terahertz (THz) intersubband emission and detection. Intersubband Transitions in Quantum Wells: Physics and Devices will be of interest to researchers from universities and industrial laboratories working on physics and devices of nanostructures, and researchers in the infrared (IR) community.
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 1992 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some 30 lectures consider phenomena associated with electrical charges passing through very thin (less than 15 nm) layers of semiconductor material. The optical nonlinearities that result have application in the electronic-devices industry, and provide a real-life example of theoretical one-dimensio"
Book Synopsis Photoinduced Electron Transfer Counter to the Bias Field in Coupled Quantum Wells by :
Download or read book Photoinduced Electron Transfer Counter to the Bias Field in Coupled Quantum Wells written by and published by . This book was released on 1992 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical excitation of electrons in an asymmetric double quantum well is theoretically examined. The well is biased to align the excited levels and permit resonant electron tunneling. Emphasis is made on the photoinduced transfer of electrons counter to the bias electric field force. A density- matrix approach is developed to describe optical excitations in the presence of an arbitrary dephasing. The excitation profiles obtained for cases of different dephasing reveal the full range of tunneling coupling between the wells from completely coherent to incoherent (stepwise).
Book Synopsis Hot Carriers in Semiconductors by : Karl Hess
Download or read book Hot Carriers in Semiconductors written by Karl Hess and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 575 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains invited and contributed papers of the Ninth International Conference on Hot Carriers in Semiconductors (HCIS-9), held July 3 I-August 4, 1995 in Chicago, Illinois. In all, the conference featured 15 invited oral presentations, 60 contributed oral presentations, and 105 poster presentations, and an international contingent of 170 scientists. As in recent conferences, the main themes of the conference were related to nonlinear transport in semiconductor heterojunctions and included Bloch oscillations, laser diode structures, and femtosecond spectroscopy. Interesting questions related to nonlinear transport, size quantization, and intersubband scattering were addressed that are relevant to the new quantum cascade laser. Many lectures were geared toward quantum wires and dots and toward nanostructures and mesoscopic systems in general. It is expected that such research will open new horizons to nonlinear transport studies. An attempt was made by the program committee to increase the number of presen tations related directly to devices. The richness of nonlocal hot electron effects that were discussed as a result, in our opinion, suggests that future conferences should further encourage reports on such device research. On behalf of the Program and International Advisory Committees, we thank the participants, who made the conference a successful and pleasant experience, and the support of the Army Research Office, the Office of Naval Research, and the Beckman Institute of the University of Illinois at Urbana-Champaign. We are also indebted to Mrs. Sara Starkey and Mrs.
Book Synopsis Proceedings of the 2nd International Conference on Electronic Engineering and Renewable Energy Systems by : Bekkay Hajji
Download or read book Proceedings of the 2nd International Conference on Electronic Engineering and Renewable Energy Systems written by Bekkay Hajji and published by Springer Nature. This book was released on 2020-08-14 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book includes papers presented at the Second International Conference on Electronic Engineering and Renewable Energy (ICEERE 2020), which focus on the application of artificial intelligence techniques, emerging technology and the Internet of things in electrical and renewable energy systems, including hybrid systems, micro-grids, networking, smart health applications, smart grid, mechatronics and electric vehicles. It particularly focuses on new renewable energy technologies for agricultural and rural areas to promote the development of the Euro-Mediterranean region. Given its scope, the book is of interest to graduate students, researchers and practicing engineers working in the fields of electronic engineering and renewable energy.
Book Synopsis Electrical & Electronics Abstracts by :
Download or read book Electrical & Electronics Abstracts written by and published by . This book was released on 1997 with total page 2240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theoretical Studies of Electron Dynamics and Relaxation in Photoexcited Quantum Well Structures by : James Louis Educato
Download or read book Theoretical Studies of Electron Dynamics and Relaxation in Photoexcited Quantum Well Structures written by James Louis Educato and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The III-V compound semiconductor devices employing quantum well (QW) structures play an essential role in the field of optoelectronics. This thesis focuses on the quantum mechanical aspects of electron dynamics and relaxation (or capture) in QW structures with particular attention paid to understanding and interpreting the results from the various optical experiments performed on QW structures. First, the transfer matrix technique used to calculate the electronic properties of QW structures is described. Next, a general discussion of the electron-phonon interactions important for QW structures is made, stressing the role of confined polar optical phonons including the electron-phonon coupling for confined slab and interface phonons. In addition, optical deformation potential phonon-electron coupling pertaining to intervalley scattering is discussed. Then, a rate equation formulation for electron and phonon dynamics in QW systems is derived. Finally, a detailed discussion describing electron dynamics and relaxation in various QW structures begins with undoped QW structures. This development is followed by a discussion of electron capture in modulation-doped QW structures. Finally, intersubband transitions in asymmetric QW structures stressing the role of interface phonon modes is presented.
Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Intersubband Dynamics in Semiconductor Quantum Wells by : Inès Waldmüller
Download or read book Intersubband Dynamics in Semiconductor Quantum Wells written by Inès Waldmüller and published by . This book was released on 2005 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Asymmetric Quantum Well Structures for Enhanced Infrared Photon Absorption by : Mehjabeen Akhtar Khan
Download or read book Asymmetric Quantum Well Structures for Enhanced Infrared Photon Absorption written by Mehjabeen Akhtar Khan and published by . This book was released on 2013 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compared to inter-band transition for photon absorption in a quantum wells, intra-band (or inter-subband) transitions in heterojunction (GaAs/InP) quantum wells can provide access to a broader range of wavelengths for detector design, specifically detectors operating in the mid infrared region of spectrum (4-12 [micro]m) and beyond is possible. These quantum wells not only provide great flexibility in optimizing the Eigen energy levels or wavefunctions, and inter-subband optical matrix elements determining the corresponding transition probability, but also allow controlling electron-phonon scattering rates and thus electron lifetime. The research presented in this dissertation investigates asymmetric quantum well structures formed through III-V semiconductor material system such as AlGaAs/ InxGa(1-x)As/InyGa(1-y) As/AlGaAs that can further improve the responsivity through higher carrier mobility. Asymmetry is introduced by using multiple materials to form the well region. The advantage of exploring stepped quantum well structure stems from experimental evidence that such structures are capable of absorbing normal incidence and thus eliminates the requirement of incorporating additional optical coupling schemes such as grating structures. An important contribution of this research is the development of an analytical model to analyze single or multiple quantum well structures to quantify photon absorption. The physical model developed in this work is based on non-equilibrium Green's function (NEGF), Fermi's golden rule and quantum mechanical wave impedance concept. The approach has two distinct advantages. First, it is accurate, easily programmable and yet computationally efficient. Second, it facilitates quantifying the broadening of states resulting from both photon absorption and tunneling, which provides important insight for improving detection efficiency. Instead of being presented through calculations, such broadening has been simply assumed in previously reported works. The method developed in this research provides an efficient methodology to quantify the absorption rate of photons with different polarizations. The study looks into the design and analysis of the wells to enhance infrared radiation detection, and suggests mechanisms to optimize the structures in terms of material choice, composition, structural geometry and applied voltages. The high electron mobility and hence drift velocity in InGaAs ( >5×106cm/s), along with low carrier recapture lifetime, is expected to improve the detection speed of the device. Unlike GaAs/AlGaAs, the lattice mismatch at InGaAs/AlGaAs interface is likely to introduce strain in the structure. The effect of such strain as well as the layer thickness is taken into account in this work. Also, a methodology for achieving voltage tenability, i.e. the ability to detect different wavelengths at different bias voltages has been investigated. Although both n-type and p-type systems have potential for optoelectronic devices, n-type quantum wells are more advantageous because of their nearly parabolic sub-band structure. As for material consideration, direct band gap material based systems, such as AlGaAs/InGaAs and AlGaAs/GaAs, have been found to be particularly suitable for n-type QWIP photodetectors. The reason being that the electrons in such materials occupy states around the [gamma]valley where the effective mass is smaller and therefore mobility is higher; a condition which leads to higher photoresponsivity. Moreover such systems allow the possibility of highly stable device operation owing to the insensitivity of intra-band transition energies to temperature fluctuation and reduced influence of Auger recombination.
Download or read book Semiconductors written by and published by . This book was released on 2005 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Intersubband Optical Absorption of Electrons in Double Parabolic Quantum Wells of AlxGa1−xAs/AlyGa1−yAs *Project Supported by the National Natural Science Foundation of China (Grant No. 61274098). by :
Download or read book Intersubband Optical Absorption of Electrons in Double Parabolic Quantum Wells of AlxGa1−xAs/AlyGa1−yAs *Project Supported by the National Natural Science Foundation of China (Grant No. 61274098). written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Some realizable structures of double parabolic quantum wells (DPQWs) consisting of Al x Ga1− x As/Al y Ga1− y As are constructed to discuss theoretically the optical absorption due to the intersubband transition of electrons for both symmetric and asymmetric cases with three energy levels of conduction bands. The electronic states in these structures are obtained using a finite element difference method. Based on a compact density matrix approach, the optical absorption induced by intersubband transition of electrons at room temperature is discussed. The results reveal that the peak positions and heights of intersubband optical absorption coefficients (IOACs) of DPQWs are sensitive to the barrier thickness, depending on Al component. Furthermore, external electric fields result in the decrease of peak, and play an important role in the blue shifts of absorption spectra due to electrons excited from ground state to the first and second excited states. It is found that the peaks of IOACs are smaller in asymmetric DPQWs than in symmetric ones. The results also indicate that the adjustable extent of incident photon energy for DPQW is larger than for a square one of a similar size. Our results are helpful in experiments and device fabrication.
Download or read book Acta Physica Polonica written by and published by . This book was released on 2005 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Applied Science & Technology Index by :
Download or read book Applied Science & Technology Index written by and published by . This book was released on 2000 with total page 1688 pages. Available in PDF, EPUB and Kindle. Book excerpt:
