The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
N Holonyak - One of the best experts on this subject based on the ideXlab platform.
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Tunneling modulation of a quantum-well transistor laser
Journal of Applied Physics, 2016Co-Authors: Milton Feng, Curtis Wang, N HolonyakAbstract:Different than the Bardeen and Brattain transistor (1947) with the current gain depending on the ratio of the base carrier spontaneous Recombination lifetime to the emitter-collector transit time, the Feng and Holonyak transistor laser current gain depends upon the base electron-hole (e-h) Stimulated Recombination, the base dielectric relaxation transport, and the collector Stimulated tunneling. For the n-p-n transistor laser tunneling operation, the electron–hole pairs are generated at the collector junction under the influence of intra-cavity photon-assisted tunneling, with electrons drifting to the collector and holes drifting to the base. The excess charge in the base lowers the emitter junction energy barrier, allowing emitter electron injection into the base and satisfying charge neutrality via base dielectric relaxation transport (∼femtoseconds). The excess electrons near the collector junction undergo Stimulated Recombination at the base quantum-well or transport to the collector, thus supporting ...
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intra cavity photon assisted tunneling collector base voltage mediated electron hole spontaneous Stimulated Recombination transistor laser
Journal of Applied Physics, 2016Co-Authors: Milton Feng, Curtis Wang, N HolonyakAbstract:Optical absorption in a p-n junction diode for a direct-gap semiconductor can be enhanced by photon-assisted tunneling in the presence of a static or dynamic electrical field. In the transistor laser, the coherent photons generated at the base quantum-well interact with the collector field and “assist” optical cavity electron tunneling from the valence band of the base to the conduction band states of the collector. In the present work, we study the cavity coherent photon intensity effect on intra-cavity photon-assisted tunneling (ICPAT) in the transistor laser and realize photon-field enhanced optical absorption. This ICPAT in a transistor laser is the unique property of voltage (field) modulation and the basis for ultrahigh speed direct laser modulation and switching.
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Optical bandwidth enhancement of heterojunction bipolar transistor laser operation with an auxiliary base signal
Applied Physics Letters, 2008Co-Authors: Han Wui Then, Milton Feng, Gabriel Walter, N HolonyakAbstract:We report the improvement, from 10.5to22GHz, in the optical modulation bandwidth of a quantum-well (QW) heterojunction bipolar transistor laser (TL) by the use of an ac auxiliary base signal. Because of the three-terminal form of the TL, an auxiliary signal can be used to peak the photon output, e.g., Stimulated Recombination which simultaneously reduces the operating current gain, β(=ICO∕IBO), and increases the laser differential gain. A shorter effective base carrier lifetime, τ, owing to the increased QW Recombination rate (Stimulated Recombination), enhanced carrier transport to the “faster” QW collector (reduced β) and differential gain, result in a higher 3dB bandwidth (f3dB=1∕2πτ).
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collector current map of gain and Stimulated Recombination on the base quantum well transitions of a transistor laser
Applied Physics Letters, 2006Co-Authors: R Chan, Milton Feng, N Holonyak, A James, G WalterAbstract:Data are presented showing significant structure in the collector I-V characteristics of a transistor laser, a decrease (“compression”) in the common-emitter gain (β≡ΔIC∕ΔIB), that can be mapped in some detail and related to quantum well (QW) carrier Recombination. The change in gain (β) and laser wavelength corresponding to Stimulated Recombination (Stimulated emission) on QW transitions, which is compared with operation in spontaneous Recombination (cavity Q spoiled), is used with conventional transistor charge analysis to reveal the dynamic properties of the transistor laser.
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enhanced hot carrier spontaneous and Stimulated Recombination in a photopumped vertical cavity alxga1 xas gaas quantum well heterostructure with multiple top and bottom native oxide mirrors
Applied Physics Letters, 1995Co-Authors: T A Richard, N Holonyak, S A Maranowski, E I Chen, M J Ries, J G Neff, P A Grudowski, R D DupuisAbstract:Data (300 and 77 K) are presented on the photopumped laser operation of AlxGa1−xAs–GaAs vertical cavity quantum well heterostructure crystals that exhibit enhanced hot‐carrier Recombination. The mirrors defining the vertical cavity are formed by selective lateral oxidation (H2O+N2, 425 °C, 30 min) of quadruple AlAs layers separated by lower composition AlxGa1−xAs ‘‘stop’’ layers in order to create upper and lower high‐index‐step oxide‐semiconductor distributed Bragg reflector mirrors. The Q of the compact vertical‐cavity (a microcavity) enhances the spontaneous and Stimulated Recombination of hot carriers, making possible single mode laser operation at an energy corresponding to the second state of the quantum well. The laser operation can be shifted to the first state by cooling to 77 K and shifting the energy gap towards the vertical cavity resonance.
R D Dupuis - One of the best experts on this subject based on the ideXlab platform.
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enhanced hot carrier spontaneous and Stimulated Recombination in a photopumped vertical cavity alxga1 xas gaas quantum well heterostructure with multiple top and bottom native oxide mirrors
Applied Physics Letters, 1995Co-Authors: T A Richard, N Holonyak, S A Maranowski, E I Chen, M J Ries, J G Neff, P A Grudowski, R D DupuisAbstract:Data (300 and 77 K) are presented on the photopumped laser operation of AlxGa1−xAs–GaAs vertical cavity quantum well heterostructure crystals that exhibit enhanced hot‐carrier Recombination. The mirrors defining the vertical cavity are formed by selective lateral oxidation (H2O+N2, 425 °C, 30 min) of quadruple AlAs layers separated by lower composition AlxGa1−xAs ‘‘stop’’ layers in order to create upper and lower high‐index‐step oxide‐semiconductor distributed Bragg reflector mirrors. The Q of the compact vertical‐cavity (a microcavity) enhances the spontaneous and Stimulated Recombination of hot carriers, making possible single mode laser operation at an energy corresponding to the second state of the quantum well. The laser operation can be shifted to the first state by cooling to 77 K and shifting the energy gap towards the vertical cavity resonance.
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Enhanced hot‐carrier spontaneous and Stimulated Recombination in a photopumped vertical cavity AlxGa1−xAs–GaAs quantum well heterostructure with multiple top and bottom native oxide mirrors
Applied Physics Letters, 1995Co-Authors: T A Richard, N Holonyak, S A Maranowski, E I Chen, M J Ries, J G Neff, P A Grudowski, R D DupuisAbstract:Data (300 and 77 K) are presented on the photopumped laser operation of AlxGa1−xAs–GaAs vertical cavity quantum well heterostructure crystals that exhibit enhanced hot‐carrier Recombination. The mirrors defining the vertical cavity are formed by selective lateral oxidation (H2O+N2, 425 °C, 30 min) of quadruple AlAs layers separated by lower composition AlxGa1−xAs ‘‘stop’’ layers in order to create upper and lower high‐index‐step oxide‐semiconductor distributed Bragg reflector mirrors. The Q of the compact vertical‐cavity (a microcavity) enhances the spontaneous and Stimulated Recombination of hot carriers, making possible single mode laser operation at an energy corresponding to the second state of the quantum well. The laser operation can be shifted to the first state by cooling to 77 K and shifting the energy gap towards the vertical cavity resonance.
T A Richard - One of the best experts on this subject based on the ideXlab platform.
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enhanced hot carrier spontaneous and Stimulated Recombination in a photopumped vertical cavity alxga1 xas gaas quantum well heterostructure with multiple top and bottom native oxide mirrors
Applied Physics Letters, 1995Co-Authors: T A Richard, N Holonyak, S A Maranowski, E I Chen, M J Ries, J G Neff, P A Grudowski, R D DupuisAbstract:Data (300 and 77 K) are presented on the photopumped laser operation of AlxGa1−xAs–GaAs vertical cavity quantum well heterostructure crystals that exhibit enhanced hot‐carrier Recombination. The mirrors defining the vertical cavity are formed by selective lateral oxidation (H2O+N2, 425 °C, 30 min) of quadruple AlAs layers separated by lower composition AlxGa1−xAs ‘‘stop’’ layers in order to create upper and lower high‐index‐step oxide‐semiconductor distributed Bragg reflector mirrors. The Q of the compact vertical‐cavity (a microcavity) enhances the spontaneous and Stimulated Recombination of hot carriers, making possible single mode laser operation at an energy corresponding to the second state of the quantum well. The laser operation can be shifted to the first state by cooling to 77 K and shifting the energy gap towards the vertical cavity resonance.
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Enhanced hot‐carrier spontaneous and Stimulated Recombination in a photopumped vertical cavity AlxGa1−xAs–GaAs quantum well heterostructure with multiple top and bottom native oxide mirrors
Applied Physics Letters, 1995Co-Authors: T A Richard, N Holonyak, S A Maranowski, E I Chen, M J Ries, J G Neff, P A Grudowski, R D DupuisAbstract:Data (300 and 77 K) are presented on the photopumped laser operation of AlxGa1−xAs–GaAs vertical cavity quantum well heterostructure crystals that exhibit enhanced hot‐carrier Recombination. The mirrors defining the vertical cavity are formed by selective lateral oxidation (H2O+N2, 425 °C, 30 min) of quadruple AlAs layers separated by lower composition AlxGa1−xAs ‘‘stop’’ layers in order to create upper and lower high‐index‐step oxide‐semiconductor distributed Bragg reflector mirrors. The Q of the compact vertical‐cavity (a microcavity) enhances the spontaneous and Stimulated Recombination of hot carriers, making possible single mode laser operation at an energy corresponding to the second state of the quantum well. The laser operation can be shifted to the first state by cooling to 77 K and shifting the energy gap towards the vertical cavity resonance.
A Wolf - One of the best experts on this subject based on the ideXlab platform.
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Electron‐ion Recombination in merged beams
AIP Conference Proceedings, 2008Co-Authors: A Wolf, D. Habs, A. Lampert, Reinhard Neumann, Ulrich Schramm, T. Schüssler, D SchwalmAbstract:Detailed studies of Recombination processes between electrons and highly charged ions have become possible by recent improvements of merged‐beams experiments. We discuss in particular measurements with stored cooled ion beams at the Test Storage Ring (TSR) in Heidelberg. The cross section of dielectronic Recombination was measured with high energy resolution for few‐electron systems up to the nuclear charge of Cu at a relative energy up to 2.6 keV. At low energy (≊0.1 eV) total Recombination rates of several ions were measured and compared with calculated radiative Recombination rates. Laser‐Stimulated Recombination of protons and of C6+ ions was investigated as a function of the photon energy using visible radiation. Both the total Recombination rates and the Stimulated Recombination spectra indicate that in spite of the short interaction time in merged beams, also collisional capture of electrons into weakly bound levels (related to three‐body Recombination) could be important.
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laser Stimulated Recombination spectroscopy in highly charged rydberg ions
Bulletin of the American Physical Society, 1996Co-Authors: G Uhlenberg, T Schuessler, U Schramm, D Schwalm, A WolfAbstract:The high-angular-momentum Rydberg state structure of berylliumlike N3+ has been measured using laser-Stimulated two-step Recombination spectroscopy. A 65 MeV beam of N4+ ions from the MPI tandem accelerator is stored in the heavy-ion storage ring TSR and is velocity-matched with a colinear electron beam in the electron cooler section of the ring. Intense pulsed lasers stimulate selective electron capture into a high Rydberg state, followed by de-excitation to a specific lower Rydberg level. Results will be reported for weakly-perturbed high angular momentum components of the n=13-8 and n=13-7 transitions in N3+. Comparisons will be presented with previous measurements of low-n Rydberg transitions, with polarization model predictions, and with atomic structure calculations. The extension of the measurements to strongly-perturbed angular momentum states will be discussed.
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laser Stimulated Recombination spectroscopy for the study of long range interactions in highly charged rydberg ions
Physical Review Letters, 1995Co-Authors: T. Schüssler, U Schramm, D Schwalm, D. Habs, T Ruter, C Broude, M Grieser, A WolfAbstract:The energy shifts of high-angular-momentum Rydberg states in berylliumlike O{sup 4+}, due to long-range interactions of the Rydberg electron with the ionic core, are measured by laser spectroscopy, using Stimulated two-step Recombination of free electrons with O{sup 5+} ions. The comparison of the accurate experimental results with theoretical shifts from the core polarization model and from {ital ab} {ital initio} atomic structure calculations shows considerable disagreement, demonstrating the need for an efficient method to include configuration interaction in a long-range interaction model.
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Laser-Stimulated formation and stabilization of antihydrogen atoms
Hyperfine Interactions, 1993Co-Authors: A WolfAbstract:Laser-Stimulated radiative transitions from states close to the ionization threshold to low-lying atomic levels are considered for protons (antiprotons) in a cold electron (positron) plasma and estimates for the resulting formation rate of hydrogen (antihydrogen) atoms in the ground state are given. The estimates apply to both laser-Stimulated Recombination and induced radiative stabilization of high Rydberg levels. First experiments concerning laser-Stimulated Recombination in merged beams of electrons and protons are discussed, which have confirmed the rate predictions for this process. In view of antihydrogen formation in a cold trapped positron plasma, the use of two successive Stimulated transitions is considered for obtaining a high formation rate of ground-state atoms at relatively low radiation intensity.
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laser Stimulated radiative Recombination
1992Co-Authors: A WolfAbstract:In this paper, we shall discuss the effect of laser-Stimulated transitions on the rate of radiative electron-ion Recombination, considering in particular merged beams of electrons and protons or highly charged ions. We shall present theoretical predictions concerning the spontaneous and Stimulated Recombination rates and discuss the limitation of the Stimulated rate by photoionization. The emphasis in this discussion will be on transitions into Rydberg states, which play an important role especially for Recombination involving highly charged ions. Recent experiments demonstrating laser-Stimulated Recombination in merged electron and proton beams will be reviewed and a perspective of future experiments will be given.
Susan M Rosenberg - One of the best experts on this subject based on the ideXlab platform.
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evidence for both 3 and 5 single strand dna ends in intermediates in chi Stimulated Recombination in vivo
Genetics, 1996Co-Authors: Haide Razavy, Susan K Szigety, Susan M RosenbergAbstract:This paper focuses on elucidation of the structures of intermediates in Recombination Stimulated by Chi Recombination hotspots in vivo. We report that null mutations in genes encoding single-strand exonucleases of 3’ polarity, Exonuclease I (Exo I), of 5’ polarity, RecJ, and of both polarities, Exo VII, alter the ability of Chi sites to promote Recombination, and diminish the frequency of Recombination. Maximal effects occur when single-strand exonucleases of both polarities are eliminated. These data imply that 3’ and 5’ single-strand DNA ends, the substrates for these exonucleases, exist in bona fide , product-generating intermediates in Chi-Stimulated Recombination in vivo. These results also identify three new proteins not known previously to affect RecBCD-mediated Recombination.
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evidence for both 3 prime and 5 prime single strand dna ends in intermediates in chi Stimulated Recombination in vivo
Genetics, 1996Co-Authors: Haide Razavy, Susan K Szigety, Susan M RosenbergAbstract:This paper focuses on elucidation of the structures of intermediates in Recombination Stimulated by Chi Recombination hotspots in vivo. We report that null mutations in genes encoding single-strand exonucleases of 3{prime} polarity, Exonuclease I (Exo I), of 5{prime} polarity, RecJ, and of both polarities, Exo VII, alter the ability of Chi sites to promote Recombination, and diminish the frequency of Recombination. Maximal effects occur when single-strand exonucleases of both polarities are eliminated. These data imply that 3{prime} and 5{prime} single-strand DNA ends, the substrates for these exonucleases, exist in bona fide, product-generating intermediates in Chi-Stimulated Recombination in vivo. These results also identify three new proteins not known previously to affect RecBCD-mediated Recombination. 37 refs., 5 figs., 2 tabs.