Photoluminescence and optical absorption in CaS : Eu2+ : Sm3+ thin films
| Autor: | Ji-Guang Zhang, Z. L. Hua, G. M. Storti, P. K. Soltani, Manfred Wuttig, Lourdes Salamanca-Riba, P. C. Eklund |
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| Rok vydání: | 1992 |
| Předmět: |
Photoluminescence
Materials science business.industry Band gap Mechanical Engineering Analytical chemistry Condensed Matter Physics Ion Optics Mechanics of Materials Absorptance General Materials Science Photoluminescence excitation Thin film Absorption (electromagnetic radiation) business Refractive index |
| Zdroj: | Journal of Materials Research. 7:411-417 |
| ISSN: | 2044-5326 0884-2914 |
| DOI: | 10.1557/jmr.1992.0411 |
| Popis: | The optical absorption and photoluminescence of Eu2+ : Sm3+-doped CaS films have been investigated in this paper. The energy dependence of the refractive index and absorption coefficient of the film were obtained by analyzing transmission and reflection spectra of the thin film. The refractive index at low energies is very close to the bulk value for CaS (n = 2.03) and decreases with increasing energy in the range of 1.2 to 2.5 eV. The energy gap of CaS: Eu2+ : Sm3+ thin films is found to be a direct gap with value Eg = 4.48 eV. Photoluminescence studies on annealed CaS: Eu2+ : Sm3+ thin films showed a broad band at ∼1.92 eV identified with emission from Eu2+ ions, and a set of sharp lines corresponding to emission from Sm3+ ions. Most of the strong features presented in the room temperature spectra are found in good agreement with previous bulk studies of CaS: Eu2+ and CaS: Sm3+. The abnormal increase of the Sm3+ photoluminescence with increasing temperature is explained by the phonon-assisted energy transfer from Eu2+ ions to Sm3+ ions. |
| Databáze: | OpenAIRE |
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