Dokument: Occupation dynamics of self-assembled quantum dots and deep level traps
| Titel: | Occupation dynamics of self-assembled quantum dots and deep level traps | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=66700 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20240909-090757-0 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Berg, Lukas [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Heinzel, Thomas [Gutachter] Prof. Dr. Horbach, Jürgen [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | This thesis focuses on the occupation dynamics of self-assembled quantum dots (SAQDs) and deep level traps. SAQDs are nanoscale crystalline structures with dimensions small enough to exhibit only a discrete density of states for charge carriers. Embedded in a host crystal, these energetic states can lie within the forbidden bandgap. The free charge carriers of the crystal can interact with these discrete states, they can be captured, stored and emitted. Placing these SAQDs in a Schottky junction allows for observation of their occupation by the junction’s capacitance and for precise control over the electric field and charge carrier density at the SAQDs position. Capacitance transient spectroscopy was used in this thesis to isolate the electron capture and emission rates.
Within this thesis three research projects were conducted. The first project investigates the capture of electrons into SAQDs that are far from their reservoirs (> 100 nm). Capture rates were extracted from the capacitance transients as a function of the electric field, the temperature and the applied magnetic field. The studies identified the back contact of the Schottky junction as the dominant electron source. A model was developed to describe electron diffusion from the back contact to the SAQDs position. Capture by tunneling is possible for small barriers, as identified experimentally. Furthermore, the extracted capture and emission rates were used to model the hysteretic capacitance voltage characteristics quantitatively. In the second project an electrostatic coupling between two layers of SAQDs at a distance of 200 nm is observed. The coupling manifests itself by a modulation of the capture and emission rates of one layer based on the electric field generated by the respective other layer. A model based on rate equations explains the observations quantitatively. Defects in the crystal lattice of a semiconductor can also modify their surrounding potential to discrete energetic states within the bandgap, the deep level traps. The third project introduces the deep level transient photocapacitance spectroscopy, a novel technique for extracting parameters of deep level traps from their temperature dependent photocapacitance transients. The oxygen vacancy in rutile titanium dioxide acted as a platform, a rolled-up nanomembrane, used as electrode, allowed a high illumination rate. | |||||||
| Lizenz: |  Dieses Werk ist lizenziert unter einer Creative Commons Namensnennung 4.0 International Lizenz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Physik der kondensierten Materie | |||||||
| Dokument erstellt am: | 09.09.2024 | |||||||
| Dateien geändert am: | 09.09.2024 | |||||||
| Promotionsantrag am: | 25.07.2024 | |||||||
| Datum der Promotion: | 29.08.2024 |
