On the role of interface properties in the degradation of metalorganic vapor phase epitaxially grown Fe profiles in InP

Fe doping profiles in InP layers grown by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) were investigated by secondary ion mass spectroscopy. Different pre-treatments of the InP substrates proved to have substantially different effects on the Fe profiles which strongly indicate the relevance of underlying interfaces to dopant diffusion in subsequent layers, at least in the case of dopants occupying the group-III sublattice. We attribute the degradation of Fe profiles observed for some kinds of treatment to the emission of In interstitials from surfaces covered by oxides or other residues which are incompletely removed during the MOVPE preheat cycle. A favorable substrate preparation method for avoiding Fe profile degradation relies on etching by 5:1:1 H₂SO₄:H₂O₂:H₂O at room temperature followed by 30 min deionized water rinsing.     

Bücherschau

Ohne Zusammenfassung VDI     

Spurenstoffabtrennung mit keramischen Nanofiltrationsmembranen als Rotationsscheibenfilter

Reducing micropollutant pollution of water bodies is an important objective of water management and an integral part of environmental policy. Ceramic nanofiltration membranes were developed as multichannel membranes of increased membrane area and rotating disk filters. The membranes developed show retention of over 80 % for PEG 400. The membranes are currently being tested for the separation of micropollutants from wastewater contaminated with pharmaceuticals. With the help of a downstream oxidative process, the trace substances remaining in the permeate are degraded.     

Water-core waveguide for pollution measurements in the deep ultraviolet

A fiber optic system for water analysis with high transparency in the deep-UV region (lambda >/= 190 nm) is presented. The system consists of special UV-improved silica fibers and a liquid-core waveguide (LCW) as an optical cell. The apertures of both light guides, the silica fiber and the LCW, are matched. The optical losses of the device are investigated experimentally and compared with theory, especially with a standard free-space geometry. The performance of the system with respect to UV absorption spectroscopy is demonstrated for nitrate and chlorine pollution in pure water. For a 203-mm-long LCW the detection limits have been determined to be as low as 22 mug/L for nitrate and 26 mug/L for chlorine.     

Slanted Stixels: A Way to Represent Steep Streets

International Journal of Computer Vision - This work presents and evaluates a novel compact scene representation based on Stixels that infers geometric and semantic information. Our approach...     

Photoinduced reversible refractive index changes in doped poly(methyl methacrylate) lightguides

Planar polymer lightguides of poly(methyl methacrylate)(PMMA) doped with the azo dye, N,N-dihexyl-4-amino-4′-nitro-azobenzene (DHANA) were fabricated on a suitable glass substrate or on one surface of a regular prism. The absorption of this azo dye is strong in the green spectral region. With the red light of a HeNe laser (633 nm) these polymer films may be used as lightguides. However, in this spectral region, the guided light influences the waveguiding properties of the polymer film, making this combination a possible candidate for an all optical device material. The observed refractive index changes are intensity dependent and the response time is of the order of 100ms.     

Bücherschau

Ohne Zusammenfassung VDI     

The politics of co-design in ICT for sustainable development

ABSTRACT

In this paper, we discuss an approach to co-design in ICT for sustainable development. We first set out to consider sustainable development as incorporate a concern for resilience, adaptability, and autonomy. We then draw on an ongoing participatory design project to illustrate how co-design projects can be configured, along with the political choices that this entails, to support such development.