Author: Carmen Ocal

Influence of twinned structure on the morphology of CdTe(111) layers grown by MOCVD on GaAs(100) substrates

2003

Abstract The morphology and structure of CdTe(1 1 1) layers grown on GaAs(1 0 0) by MOCVD have been studied by atomic force microscopy (AFM) and X-ray texture analysis. Growth conditions have been chosen so that mirror-like CdTe layers are obtained. Layers whose growth times vary between 10 s and 2 h have been investigated. The X-ray texture analysis shows that the CdTe layers grown on GaAs substrates that were thermally treated at 580°C for 30 min in a H 2 atmosphere exhibit a (1 1 1) preferential orientation and are twinned. This twinned structure of the (1 1 1)CdTe layer which is observed as 60° rotated triangular crystallites in the AFM images strongly influences the surface morphology.…

Inorganic ChemistryCrystallographyChemistryMaterials ChemistryHeterojunctionCrystalliteMetalorganic vapour phase epitaxyTexture (crystalline)Chemical vapor depositionThin filmCondensed Matter PhysicsCrystal twinningCadmium telluride photovoltaicsJournal of Crystal Growth

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Structural analysis of CdO layers grown on r-plane sapphire (011¯2) by metalorganic vapor-phase epitaxy

2004

Abstract High-quality fully relaxed CdO layers have been grown directly on r -plane sapphire by metalorganic vapor-phase epitaxy. The crystalline structure has been analyzed by high-resolution X-ray diffraction. The structural quality of the (0 0 1) oriented layers degrades as the growth temperature decreases, process which is accompanied by the appearance of pyramidal grains as revealed by scanning force microscopy. The lattice parameters, perpendicular and parallel to the sample surface, have been determined by means of reciprocal space maps taken on asymmetrical reflections and measurements of symmetrical reflections at different azimuths. The epitaxial relationships between the CdO laye…

Diffractionbusiness.industryChemistryCrystal structureCondensed Matter PhysicsEpitaxyInorganic ChemistryReciprocal latticeCrystallographyLattice (order)Materials ChemistryPerpendicularSapphireOptoelectronicsThin filmbusinessJournal of Crystal Growth

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Morphology of ZnO grown by MOCVD on sapphire substrates

2004

A quantitative roughness and microstructural analysis of ZnO grown on sapphire by atmospheric metalorganic chemical vapor deposition (MOCVD) is presented. In order to investigate the influence of the substrate on the morphology, different sapphire orientations have been employed. Scanning force microscopy data have been analyzed for a variety of thicknesses to elucidate, if possible, the growth mechanisms involved in the growth process. Our study reveals significant differences between morphologies depending on whether the substrate surface exhibits steps (misoriented a-, c- and r-planes) or not (m-plane); however, no major differences on the calculated roughness coefficients have been foun…

Morphology (linguistics)ChemistryMineralogySurface finishSubstrate (electronics)Chemical vapor depositionCondensed Matter PhysicsMicrostructureInorganic ChemistryChemical engineeringMaterials ChemistrySapphireMetalorganic vapour phase epitaxyThin filmJournal of Crystal Growth

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Twin coarsening in CdTe(111) films grown on GaAs(100)

2006

Abstract We present a scanning force microscopy study of twin coarsening in CdTe(1 1 1) films grown on GaAs(1 0 0). Two types of CdTe(1 1 1) twins grow epitaxially and with equal probability on the long-range wavy surface structure developed by previous in situ annealing of the GaAs(1 0 0) substrate. Due to this initial substrate wavy structure, the grain coarsening during film growth leads to a quasi-one-dimensional rippled pattern. We propose a coarsening mechanism between twins driven by the formation of stacking faults.

Materials sciencePolymers and PlasticsCondensed matter physicsAnnealing (metallurgy)business.industryMetals and AlloysStackingEpitaxyMicrostructureCadmium telluride photovoltaicsElectronic Optical and Magnetic MaterialsCrystallographySemiconductorCeramics and CompositesCrystal twinningbusinessStacking faultActa Materialia

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Nanosession: Valence Change Memories - A Look Inside

2013

Materials scienceCondensed matter physicsValence (psychology)

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Faceting and structural anisotropy of nanopatterned CdO(110) layers

2005

CdO(110) layers with a self-organized surface structure have been grown on (10math0) sapphire (m plane) substrates by metal-organic vapor phase epitaxy. The epitaxial relationships between layer and substrate have been determined and a crystallographic model that accounts for the CdO in-plane orientation, which results in a reduced lattice mismatch when the CdO[001] direction is perpendicular to the sapphire c axis, has been proposed. Although the measured lattice parameters indicate that the layers are almost fully relaxed, an anisotropic mosaicity is detected with symmetrical rocking curves attaining minimum values when measured along the CdO[math10] direction. The layer morphology consis…

Materials scienceGeneral Physics and AstronomySemiconductor growthEpitaxyMosaicityVapour phase epitaxial growthCadmium compound ; Semiconductor epitaxial layers ; II-VI semiconductors ; Semiconductor growth ; Vapour phase epitaxial growth ; MOCVD ; Nanopatterning ; Self-assembly ; Lattice constants ; Mosaic structure ; Surface morphologyLattice constant:FÍSICA [UNESCO]PerpendicularMetalorganic vapour phase epitaxyAnisotropyCondensed matter physicsUNESCO::FÍSICASemiconductor epitaxial layersLattice constantsNanopatterningII-VI semiconductorsSelf-assemblyFacetingCrystallographyCadmium compoundMOCVDSapphireSurface morphologyMosaic structure

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Electron Accumulative Molecules.

2018

With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B–N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B–N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C2B9H11)(C2B9H10)-NC5H4-…

010405 organic chemistryChemistryelectronsViologenmolekyylitGeneral ChemistryElectron010402 general chemistryelektronit01 natural sciencesBiochemistryChemical synthesisCatalysis0104 chemical sciencesCrystallographySingle electronColloid and Surface ChemistryElectrophileCluster (physics)medicineMoleculemoleculesta116Chemical decompositionmedicine.drugJournal of the American Chemical Society

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