A study of the reactivity of elemental Cr/Se/Te thin multilayers using X-ray reflectometry, in situ X-ray diffraction and X-ray absorption spectroscopy |
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Authors: | Malte Behrens,Enno May,Wolfgang Bensch,Dietrich Hä uß ler |
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Affiliation: | a Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel, Olshausenstr. 40-60, 24098 Kiel, Germany b Mikrostrukturanalytik, Technische Fakultät, Christian-Albrechts-University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany |
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Abstract: | The reactivity of [Cr/Se/Te] multilayers under annealing was investigated using X-ray reflectometry, in situ X-ray diffraction, X-ray absorption fine structure (XAFS) measurements and transmission electron microscopy. For all samples, interdiffusion was complete at temperatures between 100 and 300 °C, depending on the repeating tri-layer thickness. A crystalline phase nucleated approximately 20 °C above the temperature where interdiffusion was finished. The first crystalline phase in a binary Cr/Te sample was layered CrTe3 nucleating at 230 °C. In ternary samples (Se:Te=0.6-1.2), the low-temperature nucleation of such a layered CrQ3 (Q=Se, Te) phase is suppressed and instead the phase Cr2Q3 nucleates first. Interestingly, this phase decomposes around 500 °C into layered CrQ3. In contrast, binary Cr/Se samples form stable amorphous alloys after interdiffusion and Cr3Se4 nucleates around 500 °C as the only crystalline phase. Evaluation of the XAFS data of annealed samples yield Se-Cr distances of 2.568(1) and 2.552(1) Å for Cr2Q3 and CrQ3, respectively. In the latter sample, higher coordination shells around Se are seen accounting for the Se-Te contacts in the structure. |
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Keywords: | Chromium chalcogenides Modulated elemental reactants Multilayer thin films Anion substitution |
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