Growth, chemical composition, and structure of thin La x Hf1 − x O y films on Si
| Autor: | Tamara P. Smirnova, L. V. Yakovkina, Andrey A. Saraev, Vasily V. Kaichev, V. O. Borisov, V. N. Kichai |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Materials science
General Chemical Engineering Metals and Alloys Analytical chemistry Pyrochlore chemistry.chemical_element Crystal structure engineering.material Hafnium Inorganic Chemistry chemistry.chemical_compound Crystallography chemistry X-ray photoelectron spectroscopy Materials Chemistry Lanthanum engineering Chemical composition Hafnium dioxide Solid solution |
| Zdroj: | Inorganic Materials. 50:158-164 |
| ISSN: | 1608-3172 0020-1685 |
| Popis: | The chemical structure, phase composition, and crystal structure of LaxHf1 − xOy films grown on Si using volatile metalorganic compounds as Hf and La precursors have been studied by X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray microanalysis, and atomic force microscopy. By varying the lanthanum and hafnium source temperatures, we were able to grow films with 2 at % < CLa < 30 at %. The Hf 4f and La 3d peak positions in the XPS spectra of the films correspond to hafnium and lanthanum in the Hf4+ and La3+ states. With increasing La concentration, the reflections in the X-ray diffraction patterns of the films shift to smaller 2θ angles, indicating the formation of solid solutions. At 18 at % La, we observed a transition from a fluorite-like structure to the pyrochlore structure (La2Hf2O7). The film containing 30 at % La consisted of a mixture of c-La2O3 and La2Hf2O7. The surface roughness of the films was shown to increase with increasing La concentration. Capacitance-voltage (C-V) measurements were used to assess the relative permittivity (k) of the films as a function of La concentration. The minimum k value was obtained at the La concentration corresponding to the transition from the fluorite structure to an ordered pyrochlore structure (second-order phase transition). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|