Evaluation of InP/InGaAsP distributed Bragg reflectors grown by chemical-beam epitaxy

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

We have applied the sol-gel process to generate optical microstructures in glass using in-house developed sol-gel materials. The synthesis of our sol-gel glass materials is based on the formation of particles of controlled size from organo-metallic compounds. The overall shrinkage during annealing of the gel material is negligible and does not imply crack formation. Silica, titania and binary oxides of silica titania oxide sol-gel materials have been used. A two-step pattern transfer is employed to replicat

A transmission electron microscopy (TEM) study using weak-beam imaging has been addressed in order to assess the microstructure of NiAl (100) single-crystals subsequently to irradiation at room temperature with 700 keV nickel ions up to 10(15) cm(-2) or 1.5 dpa, namely, defect cluster formation and respective depth distribution. This work shows that the incoming ions undergo channeling along the [100] crystallographic direction and that the actual projected range is approximately 500 nm instead of the 250 n

Uniaxial fragmentation tests were carried out in situ in a scanning electron microscope (SEM) on 10-nm-thick silicon oxide coatings deposited by plasma enhanced chemical vapor deposition on poly(ethylene terephthalate). In order to prevent charging effects due to the isolating nature of the oxide surface, an additional conductive gold layer was sputtered onto the coating prior to its tensile loading in the SEM chamber. The gold layer was shown not to affect initiation of tensile failure of the oxide coating

The first part of this laboratory study deals with heterogeneous reactions of bromine- and chlorine-containing species relevant to the atmosphere with solid model alkali salt substrates. The second part of this work treats the heterogeneous interaction of acidic compounds with various mineral dust substrates. The aim of this study is to investigate the role of adsorbed water, H2O(a) and the influence of defect surface sites on the reactions. Furthermore, reaction mechanisms are proposed for the different in

Innovative structured catalysts based on nanoparticles of gold supported on activated carbon fibers (ACF) in the form of woven fabrics are presented for low-temperature CO oxidation. Gold was deposited by adsorption from aqueous solution of ethylenediamine complex [Au(en)2]Cl3 followed by reduction in hydrogen. The catalysts were studied under transient reaction conditions and characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray energy dispersive analysis (EDS). HRTEM-EDS show

A large CdTe-based tomographic system has been installed two years ago on the TORE SUPRA tokamak, for a detailed investigation of the dynamics of fast electrons generated by radio-frequency waves in Fusion plasmas, as a function of time, space and energy. With 59 chords and 8 energy channels per line-of-sight, this diagnostic is the largest in the fusion community dedicated to hard X-ray studies emitted by the plasma between 20 and 200 keV. A description of the tomography as well as its performance in the a

Using time-resolved photoluminescence, we have investigated the radiative behavior of neutral and negatively charged excitons in CdTe-based quantum wells. We find that the photoluminescence of negatively charged excitons can be well reproduced by a model of delocalized and thermalized three-particle complexes. A large radiative zone in k-space results from the transfer of the charged exciton momentum to the remaining electron (recoil effect). On the other hand, the photoluminescence decay of excitons is not

Nickel-aluminium intermetallics constitute interesting systems for the study of irradiation-induced phase transformations (order → disorder, amorphization) and production of defects. Irradiation of ordered intermetallics may induce disorder or amorphization depending on the projectile characteristics, irradiation conditions and chemical and physical properties of the target. The behavior of the various intermetallic compounds of the nickel-aluminium system with respect to electron and ion irradiation has be

In YBa2Cu3O6+x the tetragonal to orthorhombic transition occurs around x equals 0.3, followed by a continuum variation of lattice parameters. Hence both, the structural and superconducting properties, depend upon the oxygen content in CuO chains. Conversely, the epitaxial stress, exerted by the substrate on YBCO films, modified the lattice parameters, influencing the oxygen stability in the chains. The understanding of this mechanism is essential when growing epitaxial films for in-situ photoemission studie

Space charge effects (so-called negative-mass instability) as the reason for electron energy spread developing in the region of the electron drift between the cathode and the cavity of a gyrotron are discussed. The quasioptical gyrotron working at third harmonic that is developed at Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, is used to demonstrate the expected efficiency degradation.

Over almost 50 years of its development, the science of immunology has become an indispensable tool for the understanding of the histology of tissues. Antibodies are highly specific probes, so that tissue structure can be interpreted not just by morphological considerations but by association with a wide variety of physiological molecular antigens. The simple concept of an antibody linked to a microscopically dense marker remains constant in each application of the technique, such as the use of fluorescent

Transparent single crystals of Pb(Zn-1/3, Nb-2/3)O-3-PbTiO3 (PZN-PT) perovskite have been grown by the slow cooling method in a temperature gradient furnace. The optimization of growth techniques to crystallize PZN-PT with a cubic habitus is described in details. The growth temperature range and cooling rates was carried out in different lead fluxes, Crystal recovery from the residual flux was obtained by different techniques based on liquid flux elimination at the end of the growth process. The best transp

Evaluation of InP/InGaAsP distributed Bragg reflectors grown by chemical-beam epitaxy

Chat with Graph Search

The sol-gel process for realisation of optical micro-structures in glass

Channeling effects in heavy-ion irradiated NiAl(100) single-crystals: a TEM assessment in cross-section geometry using weak-beam imaging

Mechanical analysis of ultrathin oxide coatings on polymer substrates in-situ in a scanning electron microscope

Heterogeneous reactions of tropospheric trace-gases on solid model aerosol surface : a laboratory study

Structured Au/FeOx/C catalysts for low temperature CO oxidation

Hard X-ray CdTe tomography of tokamak fusion plasmas

Negatively charged excitons in CdTe-based quantum wells: A time-resolved study

The order-disorder transformation and microstructure evolution in nickel-aluminium intermetallics after heavy-ion irradiation

Structural properties of strained YBa2Cu3O6+x superconducting films grown by pulsed laser deposition

Space charge effects as a source of electron energy spread and efficiency degradation in gyrotrons

Immunohistochemistry for the MEPHISTO X-PEEM

Growth and properties of transparent Pb(Zn-1/3, Nb-2/3)O-3-PbTiO3 single crystals with a cubic habitus