Microstructural Characterization of GaAs Substrates

AbstractThe defect microstructures of GaAs substrates have been investigated in a multi-technique approach including integral cathodoluminescence (CL), scanning electron acoustic microscopy (SEAM), double crystal x-ray topography (XRT), and defect delineation etch. The XRT, CL, and SEAM studies are of identical areas on <100> SI GaAs(Cr) grown by the liquid encapsulated Czochralski (LEC) method and by the horizontal Bridgman (HB) method. Correlation was made to the defect structure revealed by defect delineation etching. The samples were also characterized by Fourier transform photoluminescence (FTPL) to qualitatively identify the major transitions contributing to the CL images. The CL, SEAM, XRT, and defect delineation etch images of each material are compared and their different perspectives are discussed.

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SEM Characterization of Silicon Layers Grown on Carbon Foil

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.156-158.473 ◽

2009 ◽

Vol 156-158 ◽

pp. 473-476 ◽

Cited By ~ 1

Author(s):

Sergei K. Brantov ◽

A.V. Eltzov ◽

Olga V. Feklisova ◽

Eugene B. Yakimov

Keyword(s):

Dislocation Density ◽

Defect Structure ◽

Growth Direction ◽

Carbon Foil ◽

Twin Boundaries ◽

X Ray ◽

Electron Backscattering Diffraction ◽

Silicon Ribbon ◽

Selective Chemical

Characterization of defect structure in silicon ribbon grown on carbon foil has been carried out. The structure of grown Si layers and a dislocation density in these layers have been studied using selective chemical etching and the Electron Backscattering Diffraction. It is observed that the layers consist of rather large grains, the majority of which is elongated along the growth direction with a similar surface orientation and with a misorientation angle between neighboring grains of 60º. This means that such grains are separated by the (111) twin boundaries. The dislocation density in different grains is found to vary from 102 to 107cm-2. The energy dispersive X-Ray microanalysis has shown that some twin boundaries are enriched with carbon.

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Influence of the Residue of Casting by Lost Wax in the Modulus of Elasticity and Porosity of Concretes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.805.343 ◽

2014 ◽

Vol 805 ◽

pp. 343-349

Author(s):

Carine F. Machado ◽

Weber G. Moravia

Keyword(s):

Construction Industry ◽

Modulus Of Elasticity ◽

Chemical Characterization ◽

Microstructural Characterization ◽

Cement Matrix ◽

X Ray Diffraction ◽

X Ray ◽

Hardened State ◽

Material Powder

This work evaluated the influence of additions of the ceramic shell residue (CSR), from the industries of Lost Wax Casting, in the modulus of elasticity and porosity of concrete. The CSR was ground and underwent a physical, chemical, and microstructural characterization. It was also analyzed, the environmental risk of the residue. In the physical characterization of the residue were analyzed, the surface area, and particle size distribution. In chemical characterization, the material powder was subjected to testing of X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The residue was utilized like addition by substitution of cement in concrete in the percentages of 10% and 15% by weight of Portland cement. It was evaluated properties of concrete in the fresh and hardened state, such as compressive strength, modulus of elasticity, absorption of water by total immersion and by capillarity. The results showed that the residue can be used in cement matrix and improve some properties of concrete. Thus, the CSR may contribute to improved sustainability and benefit the construction industry.

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