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| Author(s): |
Andre Luis de Jesus Pereira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Bauru. 2014-06-11. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências. Bauru |
| Defense date: | 2012-08-09 |
| Advisor: | José Humberto Dias da Silva; Paulo Noronha Lisboa Filho |
| Abstract | |
The search for a better understanding of the interrelation between the parameters involved in the process of film growth and the resulting structural, electronic and magnetic properties was the main motivation of this work. To the purpose, TiO2 films were grown by RF magnetron sputtering technique in different conditions. In a first set, TiO2 films were deposited with continuous O2 flow. In another set, systematic interruptions in the O2 flow were performed during the deposition. The last group of samples was deposited using a continuous O2 flow and Mn doping. A detailed analysis of the first group showed that these films exhibit columnar morphology with mainly anatase structure and optical gap of ~3.3eV, independent of the substrate temperature (450ºC and 600ºC) and the ratio used. THe decrease in O2 flux caused an increase in the sug gap absorption which associated with the increase in electronic defects of the material. Anneling in vacuum at 800ºC performed on pure TiO2 films showed an increase in the rutilo fraction, a red shift of the optical absorption edge, and an increase of the sub gap absorption associated with the increase of the electronic defects. The analysis of the films were the O2 flow was systematically interrupted during the deposition showed that the increase in the number of interruptions did not interfere significantly in the columnar morphology, but produced a significant increase in the fraction of rutile and brookite as well as an increase in sub-gap absorption. The increase in absorption in the visible and near infrared was attributable to an increase in the concentration of defects that, according to calculations based on the density functional theory, should be related to energy states provides by O vacancies. The Mn doped films also present a compact columnar morphology and a strong and systematic favoring of the rutile... (Complete abstract click electronic access below) (AU) | |
| FAPESP's process: | 08/10430-4 - Deposition Process Optimization of TiO2:Mn Films using RF Magnetron Sputtering |
| Grantee: | André Luis de Jesus Pereira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |