Probing Lattice Dynamics and Electronic Resonances in Hexagonal Ge and SixGe1-x Alloys in Nanowires by Raman Spectroscopy

de Matteis, Diego and De Luca, Marta and Fadaly, Elham M. T. and Verheijen, Marcel A. and López-Suárez, Miquel and Rurali, Riccardo and Bakkers, Erik P. A. M. and Zardo, Ilaria. (2020) Probing Lattice Dynamics and Electronic Resonances in Hexagonal Ge and SixGe1-x Alloys in Nanowires by Raman Spectroscopy. ACS Nano, 14 (6). pp. 6845-6856.

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Official URL: https://edoc.unibas.ch/79563/

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Recent advances in nanowire synthesis have enabled the realization of crystal phases that in bulk are attainable only under extreme conditions, i . e ., high temperature and/or high pressure. For group IV semiconductors this means access to hexagonal-phase Si x Ge 1- x nanostructures (with a 2H type of symmetry), which are predicted to have a direct band gap for x up to 0.5-0.6 and would allow the realization of easily processable optoelectronic devices. Exploiting the quasi-perfect lattice matching between GaAs and Ge, we synthesized hexagonal-phase GaAs-Ge and GaAs-Si x Ge 1- x core-shell nanowires with x up to 0.59. By combining position-, polarization-, and excitation wavelength-dependent μ-Raman spectroscopy studies with first-principles calculations, we explore the full lattice dynamics of these materials. In particular, by obtaining frequency-composition calibration curves for the phonon modes, investigating the dependence of the phononic modes on the position along the nanowire, and exploiting resonant Raman conditions to unveil the coupling between lattice vibrations and electronic transitions, we lay the grounds for a deep understanding of the phononic properties of 2H-Si x Ge 1- x nanostructured alloys and of their relationship with crystal quality, chemical composition, and electronic band structure.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimental Material Physics (Zardo)
UniBasel Contributors:Zardo, Ilaria and de Matteis, Diego and De Luca, Marta
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Chemical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:07 Apr 2021 13:22
Deposited On:07 Apr 2021 13:22

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