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3 Jan 2000

Volume 76, Issue 1, pp. 1-128

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Time-resolved photoluminescence in self-assembled InAs/GaAs quantum dots under strictly resonant excitation

M. Paillard, X. Marie, E. Vanelle, T. Amand, V. K. Kalevich, A. R. Kovsh, A. E. Zhukov, and V. M. Ustinov

Appl. Phys. Lett. 76, 76 (2000); http://dx.doi.org/10.1063/1.125661 (3 pages) | Cited 44 times

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We investigate the carrier dynamics in self-assembled InAs/GaAs quantum dots under strictly resonant excitation of the ground state. The spectral selectivity of the resonant excitation allows us to study the physical properties of a class of dots characterized by an energy distribution comparable to the excitation laser spectrum. We detect no Stokes shift of the photoluminescence (PL) line. The PL decay time yields a straightforward determination of the radiative recombination time. © 2000 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.47.-p Spectroscopy of solid state dynamics

Piezoelectric field and confinement effects on the dielectric function spectrum of InGaN/GaN quantum wells

A. Ramakrishnan, J. Wagner, M. Kunzer, H. Obloh, K. Köhler, and B. Johs

Appl. Phys. Lett. 76, 79 (2000); http://dx.doi.org/10.1063/1.125662 (3 pages) | Cited 7 times

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In0.13Ga0.87N/GaN double heterostructures and quantum wells (QWs) have been studied by room-temperature photoluminescence (PL) and spectroscopic ellipsometry (SE). PL revealed the presence of strong piezoelectric fields, which strongly influence the luminescence properties for InGaN QW widths in the 3–12 nm range. The pseudodielectric function spectrum derived from the SE measurements were analyzed using a multilayer approach, describing the dielectric function of the individual layers by a parametric oscillator model. The fundamental band-gap resonance in the InGaN dielectric-function spectrum was found to broaden for an InGaN layer width of 12 nm, as compared to bulk-like InGaN layers, due to piezoelectric field effects. For a much narrower QW width of 1.7 nm, however, quantum confinement was found to dominate over piezoelectric-field effects, resulting in a much sharper band-gap resonance shifted to higher energies and an increased oscillator strength. © 2000 American Institute of Physics.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.66.Fd III-V semiconductors
77.65.Ly Strain-induced piezoelectric fields
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
78.55.Cr III-V semiconductors

High-frequency-induced phase-dependent dc current by Bloch oscillator non-ohmicity

K. Seeger

Appl. Phys. Lett. 76, 82 (2000); http://dx.doi.org/10.1063/1.125663 (3 pages) | Cited 6 times

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A calculation is presented for the phase-dependent dc current induced in a semiconductor superlattice by the simultaneous application of an ac field and its phase-shifted second harmonic. The dc current is a result of the Esaki–Tsu non-ohmicity of the superlattice for the case where it Bloch oscillates. The effect provides a tool for a determination of the relaxation time of the electrons. © 2000 American Institute of Physics.
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73.50.Mx High-frequency effects; plasma effects
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Fq High-field and nonlinear effects
73.61.-r Electrical properties of specific thin films

Magnetic study of texture in multifilamentary (Bi, Pb)2Sr2Ca2Cu3O10+x tapes: Evidence for anisotropic orientation

M. R. Cimberle, C. Ferdeghini, G. Grasso, I. Pallecchi, M. Putti, and A. S. Siri

Appl. Phys. Lett. 76, 85 (2000); http://dx.doi.org/10.1063/1.125664 (3 pages) | Cited 5 times

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We present a simple method allowing the determination of the degree of texture of superconducting grains inside Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3O10+x tapes from a set of magnetic measurements. This procedure is based on the considerable anisotropy existing between the in-plane and out-of-plane critical current densities of individual crystallites in Bi-based superconducting compounds. By this method, we have monitored the evolution of the precursor Bi2Sr2CaCu2O8+y grain texturing in unreacted multifilamentary tapes in the course of the cold rolling deformation process. Evidence for anisotropic texturing, i.e., different longitudinal and transversal angle with respect to the rolling direction, has been observed. The accuracy of the method is discussed and the results compared with the current literature. © 2000 American Institute of Physics.
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74.81.Bd Granular, melt-textured, amorphous, and composite superconductors
74.72.-h Cuprate superconductors
74.25.Sv Critical currents
84.71.Mn Superconducting wires, fibers, and tapes
74.25.Ha Magnetic properties including vortex structures and related phenomena
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

Electro-optical examination of the band structure of ordered InGaAs

J. Spieler, T. Kippenberg, J. Krauß, P. Kiesel, G. H. Döhler, P. Velling, W. Prost, and F. J. Tegude

Appl. Phys. Lett. 76, 88 (2000); http://dx.doi.org/10.1063/1.125665 (3 pages)

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Using electroabsorption measurements, we have studied the effects of atomic superlattice ordering on the electronic band structure of InGaAs for different growth parameters. We have observed ordering-induced polarization anisotropy, valence-band splitting and band gap reduction strongest for 550 °C growth and 2°[111]B tilted substrates. Back-folded conduction-band states show an ordering dependent energy shift. The position of the split-off valence-band, however, is almost unaffected. An extension to extremely low growth temperatures exhibits ordering also for 450 °C growth. Atomic force microscopy measurements reveal a temperature-dependent change of InGaAs surface from step-like to island formation. © 2000 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
73.20.At Surface states, band structure, electron density of states
68.35.B- Structure of clean surfaces (and surface reconstruction)
78.20.Jq Electro-optical effects
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