| Autor: |
Panagiotis Poulopoulos, Spyridon Grammatikopoulos, C. Politis, D. Trachylis, S. D. Pappas, M. J. Velgakis |
| Rok vydání: |
2014 |
| Předmět: |
|
| Zdroj: |
Journal of Surfaces and Interfaces of Materials. 2:233-237 |
| ISSN: |
2164-7542 |
| Popis: |
Ultrathin Ni films in the range of 1‐18 nm have been grown by direct current magnetron sputtering and successive oxidization at 600 � C in a furnace in ambient air. Structural characterization via X-ray diffraction revealed the formation of single-phase NiO. Ultraviolet-visible absorption spectroscopy was used to characterize the optical properties of the films. A smooth blue shift of the optical band gap of the NiO films is observed, as the film thickness decreases. The maximum blue shift is found to be ∼280 meV for the thinnest film of 1.7 nm. The experimental absorption spectra are fitted with the aid of the Effective Mass Approximation approach and the reduced electron‐hole mass is estimated to be in the range of 0.4‐0.5 mo, mo is the free electron mass. This value is larger than values reported in literature and confirms recent first principle calculations which show that the carrier mass increases with the concentration of carriers in naturally formed p-type NiO films. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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