Homoepitaxial growth and characterization of 4H-SiC epilayers by low-pressure hot-wall chemical vapor deposition

Horizontal air-cooled low-pressure hot-wall CVD (LP-HWCVD) system is developed to get high quality 4H-SiC epilayers. Homoepitaxial growth of 4H-SiC on off-oriented Si-face (0001) 4H-SiC substrates purchased from Cree is performed at a typical temperature of 1500 degrees C with a pressure of 40 Torr by using SiH4+C2H4+H-2 gas system. The surface morphologies and structural and optical properties of 4H-SiC epilayers are characterized with Nomarski optical microscope, atomic force microscopy (AFM), x-ray diffraction, Raman scattering, and low temperature photoluminescence (LTPL). The background doping of 32 pm-thick sample has been reduced to 2-5 x 10(15) cm(-3). The FWHM of the rocking curve is 9-16 arcsec. Intentional N-doped and B-doped 4H-SiC epilayers are obtained by in-situ doping of NH3 and B2H6, respectively. Schottky barrier diodes with reverse blocking voltage of over 1000 V are achieved preliminarily.

Curs DOW-ETSEQ. Una experiència docent compartida entre la URV i l'empresa DOW

Presentació del curs DOW – ETSEQ, que té l’objectiu de formar en continguts, valors i actituds i aportar informació de última generació sobre seguretat, medi ambient i qualitat

Marginal deterioration of the silicone for facial prosthesis with pigments after effect of storage period and chemical disinfection

The failure of facial prostheses is caused by limitations in the properties of existing materials, especially flexibility and durability. Therefore, this study evaluated the marginal deterioration of a silicone used for fabrication of facial prostheses (Silastic MDX4-4210, Dow Corning Corporation, Midland, MI, USA) according to the influence of artificial aging, daily disinfection, and 2 types of pigmentation. Thirty specimens were fabricated and subdivided in 6 groups: without pigmentation, pigmented with make-up powder and iron oxide, and evaluated with and without the action of the disinfectant. Analysis of marginal deterioration was performed on a scanning electron microscope (magnification, ×5000) immediately 6 months and 1 year after fabrication of specimens, following the guidelines of ASTM International. After visual analysis of the photomicrographs, it was noticed that all groups presented marginal deterioration and alterations in surface texture with time. The use of disinfection did not contribute to the marginal deterioration of polymer (silicone), regardless of the pigmentation and artificial aging.

Environmental, health and safety cost benefit analysis in the United States chemical industry

The purpose of this research project is to determine whether there is a cost/benefit to allocating financial and other company-related resources to improve environmental, health and safety performance beyond that which is required by law. The issue of whether a company benefits from spending dollars to achieve environmental, health and safety performance beyond legal compliance is an important issue to the chemical manufacturing industry in the United States because of the voluminous and complex legal requirements impacting environmental, health and safety expenditures. The cost/benefit issue has practical significance because many U.S. chemical manufacturing companies base their environmental, health and safety management strategies on just achieving and maintaining compliance with legal requirements when in reality this strategy may actually be a higher cost way of managing environmental, health and safety practices. This difference in environmental, health and safety management strategy is being investigated to determine if managing environmental, health and safety to achieve performance beyond that which is required by law results in a greater benefit to companies in the U.S. chemical manufacturing sector.

Physico-chemical methods /

Includes tables.

The chemical and physical examination of Portland cement,

Mode of access: Internet.

A course in qualitative chemical analysis,

Mode of access: Internet.

Collision of Union Pacific Railroad train MHOTU-23 with BNSF Railway Company train MEAP-TUL-126-D with subsequent derailment and hazardous materials release, Macdona, Texas, June 28, 2004.

"PB2006-916303," "Notation 7675D."

Handbook of systematic urinary analysis, chemical and microscopical. For the use of physicians, medical students, and clinical assistants,

Microfilmed for preservation

Chemical kinetics in a reentry flow field, by M. H. Bortner.

At head of title: Space Sciences Laboratory. Aerophysics Section.

Chemical farming; its possibilities, and its mistakes. Illustrating the necessity and value of chemical elements, when rightly used, and the danger of them when the conditions are wrong; including also an examination of the Stockbridge formulas.

Mode of access: Internet.

A pronouncing chemical formula speller and contest guide,

Mode of access: Internet.

Innovative chemical supply contracts : a source of competitive advantage /

"September 1997."

A brief introduction to qualitative analysis: for use in instruction in chemical laboratories.

Translation of Einleitung indie chemische analyse