Structures and mechanical properties of alumina and aluminum-chromium oxide thin film by low temperature reactive magnetron sputtering
| Autor: | Jhe-Wei Chang, 張哲維 |
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| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 Aluminum oxide thin films were prepared by reactive direct-current sputtering under different substrate bias (substrate bias=Floating, -50 V, -100 V, -150 V, -200 V) and at low temperature of 200 °C using a tricathode sputtering system. The mechanical properties and the microstructures of the alumina films grown with different substrate bias are quite distinct. Nanoindentation tests were carried out to measure the film mechanical properties. Hardness of the films, ranging from 9 to 19 GPa, increases first with the increasing substrate bias up to -100 V, then decreases when the bias is further increased. Transmission electron microscopy analysis of the films revealed that most films are consisted of different phase ratio and of various forms of alumina nanocrystallites embedded in an amorphous matrix. The film grown on Si at substrate bias of -100 V is composed of α-alumina mainly and exhibits the maximum hardness value of 20 GPa. When the alumina film is deposited on an intermediate chromium oxide layer, it enhances to 27.6 GPa. The reasons of the enhanced film hardness may be due to the increasing fraction of α and δ alumina crystallites and the formation of nanocomposites, inhibiting dislocation formation and movement. Hardness enhanced to 26 GPa by co-sputtering aluminum-Chromium oxide thin film. XPS study proves the relationship between the chromium doping concentration caused by different bonding changes and mechanical properties. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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