Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 7 of 7
Full-Text Articles in Engineering
Tunneling Spectroscopy Of Hole Plasmons In A Valence-Band Quantum Well , B. R. Neves, T. J. Foster, L. Eaves, P. C. Main, M. Henini, D. J. Fisher, M. L. Lerch, A. D. Martin, C. Zhang
Tunneling Spectroscopy Of Hole Plasmons In A Valence-Band Quantum Well , B. R. Neves, T. J. Foster, L. Eaves, P. C. Main, M. Henini, D. J. Fisher, M. L. Lerch, A. D. Martin, C. Zhang
Faculty of Engineering - Papers (Archive)
We investigate the current-voltage characteristics of a p-doped resonant tunneling diode. In the voltage range slightly above the bias corresponding to resonant tunneling of holes into the first light-hole subband of the quantum well, we observe two satellite peaks which we attribute to plasmon-assisted tunneling transitions. A theoretical model is presented to account for these peaks. The model is based on the excitation of intrasubband and intersubband heavy-hole plasmons in the quantum well by hot holes injected close to the energy of the first light-hole subband. We also study the behavior of the satellites when a magnetic field is applied …
Dome-Shaped Space Trusses Formed By Means Of Posttensioning, G. Dehdashti, L. C. Schmidt
Dome-Shaped Space Trusses Formed By Means Of Posttensioning, G. Dehdashti, L. C. Schmidt
Faculty of Engineering - Papers (Archive)
Dome-shaped space trusses can be derived from a flat configuration by means of posttensioning. The structure considered here is devised to be a near mechanism initially and during the posttensioning operation. It is a near mechanism as only the flexural stiffness of the continuous top chords provides any resistance to deformation. Therefore, no appreciable force is induced in the members of the structure during the shape formation process. The results of experimental and theoretical work on the shape formation of a dome-shaped space truss by means of posttensioning are presented herein. An analytical procedure that includes both geometric and material …
Magneto-Photon-Phonon Resonances In Two-Dimensional Semiconductor Systems Driven By Terahertz Electromagnetic Fields, W. Xu, C. Zhang
Magneto-Photon-Phonon Resonances In Two-Dimensional Semiconductor Systems Driven By Terahertz Electromagnetic Fields, W. Xu, C. Zhang
Faculty of Engineering - Papers (Archive)
In this paper, we propose to study the magneto-photon-phonon resonance effects observed in terahertz (THz)-driven two-dimensional electron gases in strong magnetic fields. The photon energy of the THz electromagnetic radiations is on the scale of the cyclotron energy (induced by strong magnetic fields) and the LO-phonon energy so that (i) THz radiations will modify strongly the process of electron energy relaxation in the device structure; (ii) electrons can gain the energy from ac and dc driving fields through, e.g., absorption of the photons and lose the energy through, e.g., emission of the LO phonons; and (iii) resonant scattering will occur …
Emission Of Acoustic And Optical Phonons By Hot Electrons In A Two-Dimensional Electron System In Parallel Magnetic Fields, W. Xu
Faculty of Engineering - Papers (Archive)
In this paper, we present a detailed theoretical study on acoustic- and optical-phonon emission by hot electrons in AlxGa1-xAs parabolic quantum wells in parallel magnetic fields. We consider the situation where the phonon generation is detected by phonon emission experiments. The dependence of phonon emission on the magnetic field, excitation power, and phonon emission angle has been studied through calculating the electron energy loss rate in this configuration. The main results obtained from the present theoretical study are the following. (i) In low-, intermediate-, and high-energy excitations, phonon generation is mainly through electron-phonon interaction via piezoelectric, deformation-potential, and polar-optical coupling, …
Spectroscopy And Piezospectroscopy Of The Lyman Transitions And Fano Resonances Of Indium In Silicon, G. Piao, R. A. Lewis, P. Fisher
Spectroscopy And Piezospectroscopy Of The Lyman Transitions And Fano Resonances Of Indium In Silicon, G. Piao, R. A. Lewis, P. Fisher
Faculty of Engineering - Papers (Archive)
A spectroscopic investigation has been made of the p3/2 and p1/2 transitions and the bound hole associated Fano resonances of indium in silicon. Accurate values have been obtained for the transition energies of many lines. The parameters characterizing the Fano resonances have been determined and the behavior of the Fano resonances under uniaxial stress has been studied. The Fano resonances show a stress splitting similar to that of their p3/2 counterparts. Detailed piezospectroscopic data for the lines 1, 2, 3, 4, 4A, 2p, and 3p under 111, 110, and 100 compression permit a more accurate determination of deformation potential constants …
Energy States Of Be In Gaas, R. A. Lewis, T. S. Cheng, M. Henini, J. M. Chamberlain
Energy States Of Be In Gaas, R. A. Lewis, T. S. Cheng, M. Henini, J. M. Chamberlain
Faculty of Engineering - Papers (Archive)
Far-infrared absorption due to Lyman transitions of the Be acceptor in GaAs has been measured in bulk molecular-beam-epitaxy-grown samples at various temperatures and under different illumination conditions. Sharp lines of energy at 1.9 K of 134.420.06, 166.760.05, and 182.300.05 cm1 are observed, being the G, D, and C lines, respectively. Fiorentini’s recent calculation Phys. Rev. B 51, 10 161 1995 of the acceptor energy spectrum in GaAs is in good agreement with these results. At 1.9 K the G, D, and C linewidths are 1.060.14, 1.160.04, and 1.860.05 cm1, respectively, and the integrated intensities are in the ratio 11.55.6:100:57.69.8. External …
Effect Of Stress Change On Water Inflows To Underground Excavations, Buddhima Indraratna, J Wang
Effect Of Stress Change On Water Inflows To Underground Excavations, Buddhima Indraratna, J Wang
Faculty of Engineering - Papers (Archive)
The change in ground stresses in a rock mass has a significant influence on the aperture of rock joints, and therefore, on the water inflow to mining excavations. In this . paper, the distinct element code UDEC (Itasca Consulting Group, 1993) has been applied to simulate water flow through simplified joint geometries, considering appropriate joint apertures and in-situ stress ratios. For a rectangular excavation, a fully coupled hydro-mechanical analysis has been conducted. where joint conductivity is dependent on the change in apertures under applied stress, and conversely, the domain water pressures affect the deformation behaviour of the rock mass around …