Optical characterization of NiO thin-film nanostructures
| Autor: | Yi-Ming Kuo, 郭益銘 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 NiO thin-film nanostructures were grown by hot filament chemical vapor deposition method on different substrates. X-ray diffraction and Raman spectroscopy confirmed cubic structure for the nickel oxide nanostructures. Field emission scanning electron microscope (FESEM) images revealed different structural morphology for different substrate samples owing to different substrate orientations (i.e. nanowires for Si and nanocubes for sapphire substrate). Optical properties of near-band-edge emissions of NiO film deposited on sapphire are characterized using photoluminescence (PL) measurements in the temperature range between 10 and 300 K. Free exciton (FX) and bound exciton complexes (BECs) have been observed at low temperatures. Emission features originated from donor-acceptor pair (DAP) have also been determined using power dependent PL spectroscopy at 10 K. The near-band-edge transitions of NiO were characterized experimentally by thermoreflectance (TR) and transmission measurements. The experimental results showed that NiO is a direct semiconductor with band-edge transitions of A=3.27 eV and B=3.55 eV at 300 K, respectively. In comparison with the PL and TR measurements, the transition of A=3.27 eV is inferred to be an excitonic transition near band edge. On the basis of experimental results, the optical properties of NiO nanostructures have thus been realized. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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