Global ETD Search

1	Quantum-sized cadmium sulphide colloids prepared in microemulsion media Towey, Thomas January 1990 (has links) No description available. 541 Semiconductor cadmium sulphide
2	Development of electric field distribution in piezoelectric semiconductors Zold, Tibor January 1974 (has links) No description available. Electro-acoustics. Semiconductors. Piezoelectricity. Cadmium sulphide. Indium.
3	Influence of processing conditions on the structural properties of electrodeposited CdS films Nel, Jacqueline Margot 22 February 2006 (has links) Cadmium sulphide (CdS) films were electrodeposited from an aqueous electrolytic solution onto indium tin oxide and fluorine doped tin oxide substrates, commonly used in photovoltaic applications. The CdS films were deposited for between 1 minute and 4 hours at temperatures ranging from 30°C to 90°C and a deposition potential of 600 mV with respect to a Ag/AgCI reference electrode. Some films were annealed in an argon atmosphere at temperatures of 300°C, 400°C and 460°C for 15 minutes and 30 minutes with and without CdCh2 treatment. The cleaning efficiency of the substrates by several solvents was determined using atomic force microscopy (AFM), surface roughness and scanning electron microscopy (SEM). It was found that the cleaning of the substrates could be monitored by the RMS roughness of the surfaces, and that the efficiency of the cleaning methods was substrate dependent. The microstructure, composition and optical properties of the films were determined using SEM, transmission electron microscopy, transmission electron diffraction, AFM, x-ray photoelectron spectroscopy (XPS), transmittance and Raman spectroscopy. All films, including those formed at the lowest deposition temperature of 30°C, were crystalline with the hexagonal (wurtzite) structure. At deposition temperatures ≤50°C the crystallites were extremely small as evidenced by broad diffraction rings and Raman peaks. At higher deposition temperatures (≥60°C) the deposition rate increased and the crystalline quality improved significantly. At the very early stages of deposition the deposits consisted of isolated, three-dimensional particles. Rapid lateral growth of these particles dominated the initial stages of deposition. Field emission SEM and AFM showed that ostensibly single particles consisted of agglomerates of elongated and plate-like grains with no preferred orientation. The final films had a columnar structure with good contact between the substrate and the film. XPS results showed that there was no significant compositional change in the deposition temperature range used and the films were all slightly cadmium rich. Carbon, oxygen and chlorine were detected mainly on the surface of the films. After annealing, the composition of the CdS films were close to stoichiometric once the surface layer had been removed. There was an improvement in the crystallinity of the films after annealing. / Thesis (PhD (Physics))--University of Pretoria, 2006. / Physics / unrestricted UCTD
4	Development of electric field distribution in piezoelectric semiconductors Zold, Tibor January 1974 (has links) No description available. Semiconductors. Electro-acoustics. Piezoelectricity. Cadmium sulphide. Indium.
5	Efficiency limiting defects and mechanisms in CdTe/CdS heterojunction solar cells Chou, Hengchang 08 1900 (has links) No description available. Solar energy Solar cells Cadmium telluride Cadmium sulphide
6	Risks of Cadmium Nanoparticles on Estuarine Organisms : Ecotoxicological Effects of Engineered Cadmium Nanoparticles through Biochemical and Behavioral Responses in Two Marine Invertebrates, Nereis diversicolor and Scrobicularia plana Wu, Pianpian January 2012 (has links) There is an increasing concern over the safety of engineered nanoparticles (ENPs) to humans and the environment. It is important that the environmental risks of these particles to be tested under research and regulatory schemes, e.g. Nano Risks to the environment & Human Health (NanoReTox) under Seventh Framework Programme (FP7) in EU. Due to their unique properties and the fact that their detection and characterization in complex matrices is challenging, classic analytical methods and test approaches for assessing environmental risk may not be appropriate for ENPs. In this paper I present the challenges associated with ENPs exposure to the estuarine environment and the testing of a chosen ENPs to generate data on ecotoxicity in the test estuarine organisms for further consideration of risk assessment of marine environment. Careful consideration was given to the selection of the test materials (benthic organisms Nereis diversicolor and Scrobicularia plana), the test system and the test exposure conditions (CdS ENPs and aqueous CdS added to filtered natural seawater with a concentration of 10 µg L-1). Evaluation of the exposure effects was carried out by behavioral tests (burrowing kinetics and feeding rate) and biochemical responses (quantification of biomarkers). Multispecies Freshwater Biomonitor® (MFB) tests and GST analysis results show significant differences in between control group and CdS NPs exposure one, indicating that CdS NPs are potential to cause sublethal effects in test organisms. Our knowledge in environmental risk assessment of ENPs is still limited. Coordinated research is required to gain a better understanding of the factors and processes affecting ENP fate and effects in the environment as well as to develop more usable, robust and sensitive methods for characterization and detection of ENPs in environmental systems. / NanoReTox, FP7 NMP Work Programme cadmium sulphide nanoparticles ecotoxicity behavior biomarker oxidative stress Nereis diversicolor Scrobicularia plana
7	Structural and Electronic properties of β-Al2X3 (X = O, Se, Te) Maxwell, Disney O. January 2011 (has links) No description available. Electrical Engineering Materials Science CIGS Band structure Density of states Cadmium Sulphide
8	Structural, electronic and optical properties of cadmium sulfide nanoparticles / Strukturelle, elektronische und optische Eigenschaften von Cadmiumsulfid Nanoteilchen Frenzel, Johannes 08 March 2007 (has links) (PDF) In this work, the structural, electronic, and optical properties of CdS nanoparticles with sizes up to 4nm have been calculated using density-functional theory (DFT). Inaccuracies in the description of the unoccupied states of the applied density-functional based tight-binding method (DFTB) are overcome by a new SCF-DFTB method. Density-functional-based calculations employing linear-response theory have been performed on cadmium sulfide nanoparticles considering different stoichiometries, underlying crystal structures (zincblende, wurtzite, rocksalt), particle shapes (spherical, cuboctahedral, tetrahedral), and saturations (unsaturated, partly saturated, completely saturated). For saturated particles, the calculated onset excitations are strong excitonic. The quantum-confinement effect in the lowest excitation is visible as the excitation energy decreases towards the bulk band gap with increasing particle size. Dangling bonds at unsaturated surface atoms introduce trapped surface states which lie below the lowest excitations of the completely saturated particles. The molecular orbitals (MOs), that are participating in the excitonic excitations, show the shape of the angular momenta of a hydrogen atom (s, p). Zincblende- and wurtzite-derived particles show very similar spectra, whereas the spectra of rocksalt-derived particles are rather featureless. Particle shapes that confine the orbital wavefunctions strongly (tetrahedron) give rise to less pronounced spectra with lower oscillator strengths. Finally, a very good agreement of the calculated data to experimentally available spectra and excitation energies is found. PhD thesis Doktorarbeit TU-Dresden nanoparticles semiconductor quantum dot cadmium sulphide cadmium sulpfide surface structure electronic structure optical excitation density-functional theory DFT density-functional based tight-binding DFTB Doktorarbeit TU-Dresden Nanoteilchen Halbleiterquantenpunkt Cadmiumsulfid Oberflächenstruktur elektronische Struktur optische Anregung Dichtefunktionaltheorie DFT density-functional based tight-binding DFTB TD-DFT linear-response ddc:540 rvk:VE 9857 Nanopartikel Halbleiter Quantenpunkt Cadmiumsulfid Oberflächenstruktur Elektronenstruktur Photoanregung Dichtefunktionalformalismus
9	Structural, electronic and optical properties of cadmium sulfide nanoparticles Frenzel, Johannes 19 December 2006 (has links) In this work, the structural, electronic, and optical properties of CdS nanoparticles with sizes up to 4nm have been calculated using density-functional theory (DFT). Inaccuracies in the description of the unoccupied states of the applied density-functional based tight-binding method (DFTB) are overcome by a new SCF-DFTB method. Density-functional-based calculations employing linear-response theory have been performed on cadmium sulfide nanoparticles considering different stoichiometries, underlying crystal structures (zincblende, wurtzite, rocksalt), particle shapes (spherical, cuboctahedral, tetrahedral), and saturations (unsaturated, partly saturated, completely saturated). For saturated particles, the calculated onset excitations are strong excitonic. The quantum-confinement effect in the lowest excitation is visible as the excitation energy decreases towards the bulk band gap with increasing particle size. Dangling bonds at unsaturated surface atoms introduce trapped surface states which lie below the lowest excitations of the completely saturated particles. The molecular orbitals (MOs), that are participating in the excitonic excitations, show the shape of the angular momenta of a hydrogen atom (s, p). Zincblende- and wurtzite-derived particles show very similar spectra, whereas the spectra of rocksalt-derived particles are rather featureless. Particle shapes that confine the orbital wavefunctions strongly (tetrahedron) give rise to less pronounced spectra with lower oscillator strengths. Finally, a very good agreement of the calculated data to experimentally available spectra and excitation energies is found. info:eu-repo/classification/ddc/540 ddc:540

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