Optical properties of metal and semiconductor SmS thin films fabricated by rf/dc dual magnetron sputtering
| Autor: | P. Jin, Sakae Tanemura, Nataliya Nabatova-Gabain, Asuka Terai, S. Koide, Yukimasa Mori, Lei Miao |
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| Rok vydání: | 2004 |
| Předmět: |
Materials science
Condensed matter physics business.industry Band gap Analytical chemistry General Physics and Astronomy Surfaces and Interfaces General Chemistry Dielectric Molar absorptivity Sputter deposition Condensed Matter Physics Surfaces Coatings and Films Semiconductor Ellipsometry Attenuation coefficient Thin film business |
| Zdroj: | Applied Surface Science. 238:360-366 |
| ISSN: | 0169-4332 |
| DOI: | 10.1016/j.apsusc.2004.05.221 |
| Popis: | Optical properties of both metal and semiconductor phases of SmS thin films on Si substrate grown at a room temperature by dual targets (dc for metal Sm and rf for pressed powdered chalcogenide Sm 2 S 3 ) magnetron sputtering system with the concurrent adjustment of the applied power to respective target, were evaluated by SE at the photon energy range between 0.75 to 5.0 eV. This is the first work performed on the intrinsically prepared metallic sample while the former works done for the sample transformed from semiconductor to metal phase by hard polishing. The followings are concluded: (1) in the metallic film, the refractive indices n have maximum value of 2.20 at 4.10 eV, while extinction coefficient k decreases monotonically and reaches 0.03 at 5.0 eV. The absorption coefficient derived from the obtained k and the complex dielectric constant from n and k agree satisfactorily with those cited in the preceding literatures for the bulk samples; (2) in the case of semiconductor, the refractive indices n have the maximum 3.66 at 3.93 eV, while extinction coefficient k increase monotonically from 0 at 2.31 eV to 1.633 at 5.0 eV. The optical transition mode from valence to conduction band is difficult to determine as either indirect allowed or direct forbidden mode because of the insignificant difference between the linear behavior of the curves α 1/2 and that of α 2/3 ( α : absorption coefficient) as a function of photon energy beyond 3.5 eV. Hence the optical band gap E g followed by indirect allowed mode and direct forbidden mode is given as 2.67 and 2.78 eV, respectively. The agreement between the derived dielectric constant and those in the preceding literatures for bulk semiconductors is not satisfactory. |
| Databáze: | OpenAIRE |
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