MOVPE mit alternativen Quellen zur Darstellung von opto-elektronischen Bauelementen Schlussbericht

Results of atmospheric and low pressure MOVPE growth of AIAs, GaAs, InAs, GaP, InP, (AIGa)As and (AIGaIn)P structures using alternative column-III-precursors are presented. This is the first report of MOVPE growth studies for the newly developed sources: Bis-(N-Allylaminodimethylgallium), (C_1_0H_2_4N_2Ga_2); Dimethylaminopropyldimethylindium (DADI); Dimethylaminopropylalan (DAAIH_2); Trimethylaminonomethylalan, 1-(3-Diethylaminopropyl)-1-diisopropylaluminium; 1-(3-Dimehtylaminopropyl)-1-ala-cyclohexan. Electrical and optical characterization of (AIGa)As layers revealed the intramolecular alane (DAAIH-2) as an interesting group-III-precursor. In this work we have investigated the MOVPE growth of lattice matched (AIGaIn)P using standard sources, too. The influence of the growth conditions on the properties of the grown layers such as lattice mismatch, photoluminescence wavelength, FWHM of PL-peaks and the atomic ordering is discussed. A study of the MOVPE growth mode of highly strained InAs/GaAs heterostructures and InAs monolayers embedded in the bulklike GaAs is reported. (orig.)Available from TIB Hannover: F95B1378+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Nutzung externer Datenbanken durch die Hochschulen in den neuen Bundeslaendern Schlussbericht

SIGLEAvailable from TIB Hannover: DtF QN1(34,39) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Study of surface phenomena in flotation: new methods and reagents Final report

Available from TIB Hannover: DtF QN1(47,48) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

MOVPE mit neuartigen Quellen zur Darstellung von Halbleiterlasern. Teilbereich: Schichtstrukturen fuer Emitter Schlussbericht

The main task of this project has been the test of novel As- and P-precursors with lower toxicity and reduced hazardous potential for the MOVPE (metal-organic vapour phase epitaxy) of (GaIn)(PAs) and (AlGaIn)P. The investigation has been concentrated on the systematic replacement of AsH_3 and PH_3 by the compounds with lower number of As-H- and/or P-H-bonds, as tertiarybutylarsane (TBAs), ditertiarybutylarsame (DitBAs), diethyltertiarybutylarsane (DEtBAs), tertiarybutylphosphane (TBP), and ditertiarybutylphosphane (DitBuPH). (GaIn)/(PAs)/InP: The electrical and optical properties of the expitaxial (GaIn)(PAs) material have proved that the novel sources are effective and equivalent substitutes for the highly toxic AsH_3 and PH_3. Only the growth parameter window is constricted to a certain but acceptable extent. The P- and As-incorporation behaviour is improved. Especially the P incorporation is more efficient. The quaternary material can be grown with better homogeneity and reproducability over the entire composition range. MCRW laser structures designed for 1.55 #mu#m emission wavelength have been processed and characterized in cooperation with one of the project partners (Siemens AG, Munich). Threshold current densities between 1.7 and 2.0 kA cm"-"2 and T_0 values from 50 to 60 K are comparable with the data of structures grown in the standard system. MCRW laser diodes (350 x 2 #mu#m"2) with I_t_h=33 to 38 mA, #eta#=0.11 to 0.14 W/A, and T_0 between 58 and 71 K (at 60 C) don't show any changes in the short time degradation behaviour under cw operation. (AlGaIn)/P/GaAs: Using different P-precursors, the growth parameters and the properties of the epitaxial material have been verified for (GaIn)P, (AlIn)P, and (AlGaIn)P grown on (001) GaAs substrates with different misorientations. In the case of P as the only group-V lattice constituent, the growth parameter window becomes very narrow, if substituted phosphanes are used. Nevertheless, using TBP epitaxial (GaIn)P layers with optical properties comparable to the standard system can be grown. (orig.)SIGLEAvailable from TIB Hannover: F98B1479+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Modellhafte Beschreibung verkehrsbedingter Emissions- und Immissionssituationen bei Suburbanisierungsprozessen und Auswirkungen auf die Belastung staedtischer Gruen- und Freiflaechen

Traffic emissions were recorded and mapped in the vicinity of selected shopping centers (Wachau Nord, Burghausen and Paunsdorf-Center), and pollutant dispersion models were established on this basis that describe the pollutant load on the main supply roads but especially on urban recreational surfaces. In the final stage, models will be developed from which recommendations can be derived for emission reduction in urban planning, e.g. by means of decentralized shopping centers serving only a single town districtDas Vorhaben hat die Aufgabe, einen Teilaspekt der Wirkungskette 'Verkehr -Emissionen - Immissionen' modellhaft zu bearbeiten. Dabei soll besonders die zusaetzliche Verkehrsentstehung an ausgewaehlten Einkaufszentren (Globus SB Warenhaus im Gewerbegebiet Wachau Nord (im folgenden Globus-Markt genannt), Loewen-Center Burghausen und Paunsdorf-Center) am Stadtrand bzw. im suburbanen Raum untersucht und zugleich die Beeinflussung innerstaedtischer Gruenflaechen durch den Verkehr ausgewiesen werden. Erfasst und modelliert werden die Einzugsgebiete der genannten Einkaufszentren, daraus abgeleitet das Netz der Zufahrtsstrecken und die Emissionsverteilung in diesem Netz. Auf dieser Basis sind Schadstoffausbreitungsmodelle vorgesehen, die die Immissionsbelastung auf den Hauptzufahrtsstrecken beschreiben, insbesondere aber den verkehrsbedingten Schadstoffeintrag in innerstaedtische Gruen- und andere Erholungs- und Freiflaechen nachweisen. Schliesslich sollen Modelle geschaffen werden, aus denen Empfehlungen fuer eine staedtische Standortplanung resultieren, wie durch dezentralisierte, stadtteilbezogene Einrichtungen eine Verkehrs- und Emissionsreduzierung und damit auch eine Verringerung der Schadstoffbelastung an sensiblen Bezugspunkten erreicht werden kann. (orig.)Also Stadtoekologische Forschungen No. 27Available from TIB Hannover: RR 6252(2000,10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Entwicklung von Bestimmungsmethoden fuer NBL-spezifische Pflanzenschutzmittel. T. A: Entwicklung von Anreicherungsmethoden und Bestimmungsverfahren auf der Basis der Festphasenextraktion und Kapillar-GC-Technik Abschlussbericht

Analytical techniques were developed for the determination of specific plant protectives. These are substances which were permitted only in the former German Democratic Republic and which cannot be analyzed according to DIN 38407. In terms of analysis and methodology, the project focused on the development and improvement of GC-internal and GC-external enrichment processes. Within the possibilities of GC-internal analyte concentration, the injection of large-volume samples by means of PTV systematically investigated. The principle is based on the venting of water in the form of steam before the capillary column, the sorption of the analytes in the PTV-insert and subsequent thermodesorption. In principle, the method allows a larger number of plant protectives to be dealth with simultaneously, including such substances for which standardized techniques are already available. By menas of ECD, NPD or MS (SIM) detection it is possible to achieve detection limits of up to 0.01 #mu#g/l. Furthermore, PTV can be made use of as ractor for the production of volatile species from nonvolatile analytes (Buminafos, Chlormequat). Likewise, analytes can be enriched from large volumes of gaseous samples as in the case of the indirect determination of Ethephon. For a number of agents such as Methamidiphos, Trichlorfon, Butonat, Buminafos, Aldimorph and organomercury compounds, conditions were optimized for the GC-external solid-phase or liquid-liquid extraction, respectively. For this purpose, also the newly developed highly active adsorbent resin, LiChrolut EN, was used. For some agents quite specific methods were developed which are based on reaction-headspace GC (Chloral-derivatives, Ethephon). The analytical techniques developed were used for the examination of 20 raw water samples from the drinking water catchment areas of Leipzig and Halle. Only the persistent triazines and hexachlorbenzene were determined in some samples. (orig.)SIGLEAvailable from TIB Hannover: F95B1225+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Analytik Ruestungsaltlasten. T. 2: Untersuchungen zum Einfluss der Matrix Abschlussbericht

Drinking water in the Leipzig area seemed to be contaminated by explosives made and handled near the village of Elsnig in the region. The full facts became known only after 1990 and, compared with similar locations in Germany, Elsnig plays an outstanding role due to is large quantities and varieties of explosives with all their byproducts and metabilites (in same samples more than 50 components). This made is necessary to develop and validate additional analytical techniques. Particularly it was necessary to characterized an influence of the Elsnig groundwater matrix on the correctness of analytical results. The studies also focused on the efficiency of an electrochemical detector in analysing real samples. The results can be summarized as follows: Various compounds such as hexyl, hexogen, octogen, tetryl, picric acid, glycerol trinitrate and nitrobenzoic acids cannot or cannot be directly analyzed by gas chromatography. HPLC, in principle, enables all explosives, byproducts and metabolities to be separated and detected. The experimental conditions for this are given. The electrochemical detector is a valuable addition to the UV detector in analysing real samples, but cannot replace it. For the extractive enrichment of all explosives and relevant compounds of water it is necessary to work with 3 different pH-values. A suitable extraction regime was worked out. In solid phase extraction, the Elsnig real-water matrix has a rather strong influence on the recovery rates of a number of substances. In liquid extraction, this influence is considerably smaller. (orig.)Available from TIB Hannover: F96B1523+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Entwicklung eines halbtechnischen Verfahrens zur kombiniert photo- und sonochemischen Dekontamination schadstoffbelasteter Waesser Abschlussbericht

Available from TIB Hannover: F03B9 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman