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DS: Fachverband Dünne Schichten
DS 6: Thin Film Properties I
DS 6.3: Vortrag
Dienstag, 19. März 2024, 10:15–10:30, A 060
EXAFS Analysis of GeSn heteroepitaxial layers — •Sliman Gougam1, Francesco De Angelis2, Carlo Meneghini2, Giovanni Capellini1,2, and Marvin H. Zoellner1 — 1IHP-Leibniz-Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany — 2Dipartimento di Scienze, Università Roma Tre, Viale G. Marconi 446 Roma 00146, Italy
There's considerable attention focused on GeSn epitaxial layers due to their promising use in advanced optoelectronic devices. GeSn epitaxial layers quality needs to be finely tuned through growth parameters, as the arrangement of Sn within the Ge crystal lattice may play a crucial role for its application. To study atomic short-range order around Sn in these films, X-ray Absorption Fine Structure (XAFS) spectroscopy is suitable due to its chemical selectivity and sensitivity to local structure. Here, we explore the short-range order of a series of Ge1-xSnx thin films grown on Ge/Si(001) virtual substrates using MBE. Sn K-edge XAFS spectra have been measured at ESRF where results show that Sn is coordinated to 4 Ge nearest neighbors. However, a distinct variation is observed in the next neighbor shell, where the analysis shows that the number of Sn next neighbors is larger than expected for a random distribution, suggesting a chemical ordering with higher Sn-Ge-Sn affinity, which in turn is influenced by growth conditions and film composition. Average modifications in local Sn arrangement among the samples revealed by XAFS, have been correlated with changes in structural properties probed by EDX analysis, which allows to reveal the dispersion of Sn throughout the layers.
Keywords: GeSn Thin Films; MBE Growth; EXAFS Analysis; EDX Analysis