Johannes Frenzel

Structural, electronic and optical properties of cadmium sulfide nanoparticles

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http://nbn-resolving.de/urn:nbn:de:swb:14-1170678349152-44850

Kurzfassung in Englisch

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.

weitere Metadaten

übersetzter Titel
(Deutsch)
Strukturelle, elektronische und optische Eigenschaften von Cadmiumsulfid Nanoteilchen
Schlagwörter
(Englisch)
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,
Schlagwörter
(Deutsch)
Doktorarbeit, TU-Dresden, Nanoteilchen, Halbleiterquantenpunkt, Cadmiumsulfid, Oberflächenstruktur, elektronische Struktur, optische Anregung, Dichtefunktionaltheorie, DFT, density-functional based tight-binding, DFTB, TD-DFT, linear-response
SWD SchlagworteNanopartikel, Halbleiter, Quantenpunkt, Cadmiumsulfid, Oberflächenstruktur, Elektronenstruktur, Photoanregung, Dichtefunktionalformalismus
DDC Klassifikation540
RVK KlassifikationVE 9857
Institution(en) 
InstitutionTechnische Universität Dresden
AbteilungChemie und Lebensmittelchemie
BetreuerProf. Dr. Gotthard Seifert
GutachterProf. Dr. Gotthard Seifert
Prof. Dr. Michael Springborg
Prof. Dr. Alexander Eychmüller
DokumententypDissertation
SpracheEnglisch
Tag d. Einreichung (bei der Fakultät)17.10.2006
Tag d. Verteidigung / Kolloquiums / Prüfung19.12.2006
Veröffentlichungsdatum (online)08.03.2007
persistente URNurn:nbn:de:swb:14-1170678349152-44850

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