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We show how the height dispersion of self-organized InAs/InP(001) quantum islands emitting at 1.55 μm was reduced by optimizing the epitaxial growth parameters. Low height dispersion was obtained when the InAs deposit thickness was much greater than the critical thickness for two-dimensional/three-dimensional growth mode transition, and when adatom surface diffusion was favored by increasing the growth temperature or reducing the arsenic pressure during the InAs growth. When these growth conditions are not respected, the multicomponent photoluminescence spectrum obtained is explained through the common interpretation of island height varying with monolayer fluctuation. In optimized growth conditions, the multicomponent spectrum obtained is interpreted as emission from fundamental and excited levels of InAs islands with low height dispersion. Transmission electron microscopy (TEM) imaging shows that these InAs islands are stick-like, 50–100 nm in length and 22±1.2 nm in width. Cross-sectional TEM reveals flat islands, shaped like truncated pyramids, with a very homogeneous height measured at 2.4 nm. A fundamental level linewidth of 22 meV at 8 K is associated to this very narrow height distribution. Such low photoluminescence linewidth values are believed to be mainly due to the propensity of the InAs/InP(001) system to produce flat InAs islands with discrete height fluctuation. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have investigated light propagation through a single line-defect photonic crystal waveguide on a InP membrane. Modal analysis was performed using the finite-difference time-domain method. The fundamental mode has been found to be very close to the fundamental mode in a "refractive" waveguide but, in this case, it is inherently leaky. The propagation losses of this mode in the complete three-dimensional structure have been computed and measured to determine if its use could be of interest for practical applications. Propagation losses in the range of 0.1 dB/µm have been found numerically and experimentally for the fundamental mode whereas stronger out-of-plane losses have been observed for the other leaky mode within the band gap. The origins of the out-of-plane losses were then investigated and have clarified the inherent lower leakage of the fundamental mode. [ABSTRACT FROM AUTHOR]

InAs nanostructures were grown on In[sub 0.52]Al[sub 0.48]As alloy lattice matched on InP(001) substrates by molecular beam epitaxy using specific growth parameters in order to improve island self-organization. We show how the change in InAs surface reconstruction via growth temperature from (2 × 4) to (2 × 1) and/or the use of InAlAs initial buffer surface treatments improve the island shape homogeneity (either as quantum wires or as quantum dots). Differences in island shape and in carrier confinement are shown by atomic force microscopy and by photoluminescence measurements, respectively. We point out that such shape amendments induce drastic improvements to island size distribution and discernible changes in photoluminescence properties, in particular concerning polarization. [ABSTRACT FROM AUTHOR]

Presents a simulation study of the capacitance-voltage (C-V) characteristics of a single-quantum-well structure based on the self-consistent solution of the Schrödinger and Poisson equations. Numerical model of the C-V characteristics; Experimental details; Conclusion.

Investigates the effect of growth temperature and thermal treatments on the luminescence properties of SiGe/Si heterostructures grown by rapid thermal chemical-vapor deposition. Details on the experiment; Results and discussion; Conclusion.

Studies the admittance spectroscopy of InAlAs/InGaAs single-quantum-well (QW) structure with high concentration of electron traps in InAlAs layers. Factor that controls the perpendicular conductivity of the structure; Temperature dependence of the space-charge region width around the QW layer; Origin of the unusual behavior in the admittance spectra of the QW structure.

Presents information on a study which conducted optical and electrical measurements on rare earth erbium- and yttrium-doped gallium arsenide grown by molecular beam epitaxy. Methodology of the study; Results and discussion; Conclusion.

Presents a study which investigated the optical properties of ultrathin InAs/InP quantum wells grown by hydride vapor-phase epitaxy. Information on the epitaxial growth; Details of the photoluminescence investigation; Conclusion.

We have demonstrated experimentally and theoretically that losses in Tamm plasmon structures can be reduced by using a subwavelength structuration of the metal layer. The structures consist of a GaAs/Al0.95Ga0.05As Bragg reflector covered with a sub-wavelength silver grating. An active quantum dot layer is inserted to perform photoluminescence experiments. Experimental results show that the quality factor of the Tamm plasmon mode with grating increases substantially, with respect to the same structure without a grating. Moreover, a fine-tuning of the Tamm spectral position is obtained by changing the grating parameters. Finite element method simulations are in good agreement with the experimental values. Our results will promote the realization of lasing with the TP based devices at room temperature. [ABSTRACT FROM AUTHOR]

Examines the room-temperature photoreflectance (PR) of In[subx]Ga[sub1-x]As/In[sub0.52]Al[sub0.48]As single quantum wells. Process involved in growing the samples by molecular beam epitaxy; PR experimental setup; Factors attributed to peaks observed in the PR spectra; Determination of the origin of the various PR spectral features.

In the present paper, we propose an approach based on slow Bloch mode microcavity that enables the optical trapping of small nanoparticles over a broad surface. A specific design based on a double-period photonic crystal is presented. It enables an easy coupling using a wide free-space Gaussian beam and the cavity Q factor can be tuned at will. Moreover, the microcavity mode is mainly localized within the photonic crystal holes, meaning that each hole of the microcavity behaves as efficient nanotweezers. Experimental studies have shown that 200 nm and 100 nm particles can be trapped within the microcavity, in a spatial region that corresponds to the size of one hole (200 nm wide). The experimental trap stiffness has been extracted. It shows that this approach is among the most performant ones if we take into account the size of the cavity. [ABSTRACT FROM AUTHOR]

Results concerning a Bragg surface wave device based on porous silicon and intended for sensing application are reported. Existence of optical surface waves on Bragg structures is experimentally shown. Such device is expected to be very sensitive to the grafting of biological molecules. The authors demonstrate this sensing effect by grafting of amine chemical groups. The optical characterization using m-line spectroscopy shows that the increase of the coupling angle is about 20° after the amine grafting. The authors show that porosity is essential for reaching this high sensitivity. [ABSTRACT FROM AUTHOR]

Reports on the fabrication of InAs self-assembled quantum dots in InAlAs matrix grown on InP(001) substrates using Stranski-Krastanov growth mode. In-plane polarized intraband absorption observed in the 10.6-20 micrometer wavelength region; Oscillator strength of the intraband transition; Dependence of intraband absorption on carrier concentration.

Examines the electrical behavior of ytterbium (Yb) ion in p- and n-type indium phosphide grown by the synthesis method. Indication for the presence of two peaks in the conductance spectra at low temperature; Analysis on the activation energies of levels above the valence band; Attribution of conductance behavior to Yb ion.

Details an optical analysis of erbium (Er) doped gallium aluminum arsenide (GaAlAs) excited states. Growth of GaAlAs:Er sample by molecular beam epitaxy; Analysis on the temperature dependence of emissions from Er-doped GaAs; Detection of erbium excited states in GaAlAs.

Investigates the [sup 4]I[sub 13/2] --> [sup 4]I[sub 15/2] optical transition on erbium-doped Ga[sub 0.55]Al[sub 0.45]As, using time-resolved photoluminescence spectroscopy. Measured fluorescence lifetime; Indications of nonradiative transitions characterized by thermal activation; Existence of Auger losses during photoluminescence excitation; Model of excitation process.

Examines photoluminescence (PL) measurements of tensile strained In[sub 0.3]Ga[sub 0.7]As/In[sub 0.53]Ga[sub 0.7]As quantum well. Absence of intensity saturation for laser excitation in PL intensity; Decrease in PL lifetime for type I quantum well; Determination of the light holes band offset in the In[sub x]Ga[sub 1-x]As/In[sub y]Ga[sub 1-y]As quantum well.

Examines the band gap narrowing of heavy boron-doped silicon germanide (SiGe)(p[sup +])/silicon (Si)(p) heterostructures and Si(p [sup +])/Si(p) pseudoheterostructures. Growth of heterostructures by rapid thermal annealing; Use of the photoluminescence process; Observation on the energy band gap of the Si[sub 0.82]Ge[sub 0.18] alloy.

Describes observation of photoluminescence from InAs surface quantum wells grown on InP(100) by molecular beam epitaxy. Indication of the formation of InAs quantum wells on the InP surface.

GaAs and GaAlAs double-heterostructure light emitting diodes doped with erbium have been grown by molecular beam epitaxy. Both devices exhibit 1.54 μm electroluminescence (EL) at 300 K but the spectra obtained for GaAlAs:Er are much narrower than those of GaAs:Er. 1.54 μm EL has been detected for injection currents as low as 0.8 mA/cm2 and an external quantum efficiency of 10-6 has been found at 300 K. Preliminary data concerning the energy transfer from the injected carriers to the rare earth are provided. [ABSTRACT FROM AUTHOR]

We show the role played by the buffer surface morphology and by alloying effects on the size, shape and lateral distribution of InAs nanostructures grown on InP(001) substrates by molecular beam epitaxy. Three buffers, viz., In[sub 0.53]Ga[sub 0.47]As, In[sub 0.52]Al[sub 0.48]As, and InP lattice matched on InP have been studied. Differences in nanostructure morphology and in carrier confinement have been evaluated by atomic force microscopy and by low-temperature photoluminescence measurements, respectively. Alongside the classical relaxation mode through two-dimensional/three-dimensional surface morphology change, a chemical relaxation mode has to be introduced as a competitive mode of relaxation of strained layers. This chemical relaxation mode, due to alloying between the InAs deposit and the buffer, is thought to be responsible for most of the observed differences in the InAs nanostructure properties. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]