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Quality Material (quality + material)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Dewetted growth of CdTe in microgravity (STS-95)

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2004
M. Fiederle
Abstract Two CdTe crystals had been grown in microgravity during the STS-95 mission. The growth configuration was dedicated to obtain dewetting of the crystals and to achieve high quality material. Background for the performed experiments was based on the theory of the dewetting and previous experience. The after flight characterization of the crystals has demonstrated existance of the dewetting areas of the crystals and their improved quality regarding the earth grown reference sample. The samples had been characterized by EDAX, Synchrotron X-ray topography, Photoluminescence and Optical and IR microscopy. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Hg(1-x)CdxTe from short to long wave infrared on Si substrates grown by MBE

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2010
M. F. Vilela
Abstract In this paper, we show the power of using molecular beam epitaxy (MBE) for the growth of the mercury cadmium telluride (HgCdTe) system. Abrupt composition profiles, changes in doping levels, or switching doping types are easily performed. It is shown that high quality material is achieved with Hg(1- x)CdxTe grown by MBE from a cadmium mole fraction of x =0.15 to x =0.72. Doping elements incorporation as low as 1015 cm -3 for both n-type and p-type material as well as high incorporation levels >1018cm -3 for both carrier types were achieved. Secondary ion mass spectrometry (SIMS) data, x-ray data, Hall data, the influence of doping incorporation with cadmium content and growth rate, etch pit density (EPD), composition uniformity determined from Fourier transform infrared (FTIR) transmission spectroscopy, and surface defect maps from low to high x values are presented to illustrate the versatility and quality of HgCdTe material grown by MBE. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Photonic circuits writing with UV pulsed laser

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2007
K. R. Kribich
Abstract Photonics technology is employed in a growing number of applications. Biological and chemical sensors (E. Udd, Fiber Optic Sensors: An Introduction for Engineers and Scientists, Wiley, New York, 1991 [1]) for health and environment demand an adaptable technology. Network development towards the end-user requires more interconnecting components. Vision, lighting, data processing in hostile environment (spatial, military) need specific technologies. A flexible and low-cost process using good quality material is necessary. The sol-gel process is a chemical method to fabricate glasses at ambient pressure and moderate temperature. Hybrid materials (H.K. Schmidt et al., Proc. SPIE 3136, 220 (1997) [2]), mixing organic and inorganic parts, offer the advantages of polymer-like materials and glasses. We report on a new hybrid sol-gel technology to overcome the drawbacks of the formerly presented one (H. Krug, F. Teillantes, P.W. Oliviers, and H. Schmidt, Proc. SPIE 1758, 448 (1992) [3]). We present the material synthesis, an accurate and flexible fabrication process based on a pulsed UV laser lithography system and the characterisation of the optical waveguides and photonic circuits realised. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Quality Concepts for the Improved Use of Recycled Polymeric Materials: A Review

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2008
Francisco Vilaplana
Abstract Polymeric waste materials should be considered resources for the manufacture of new products through recycling processes, with a similar status to virgin fossil-based plastics and biopolymers from renewable resources. Several efforts can be made to achieve this qualitative quantum leap in plastics recycling, and consequently introduce recycled products, with competitive performance, to the market. Scientific knowledge about the degradation processes during the life cycle and the development of fast and reliable analytical methods for the quality assessment of recycled plastics are fundamental to guarantee their performance in new applications. Different strategies,restabilisation, rebuilding, compatibilisation, and addition of elastomers and fillers,can be used to upgrade the structure and properties of polymeric waste streams. This review discusses recent developments in the mechanical recycling of plastics, focusing on how to produce quality materials from waste streams and, thus, contribute to a sustainable management of resources and energy. [source]