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http://hdl.handle.net/11375/30878
Title: | Ge–GeSn Core–Shell Nanowires Under The Lens: Effects Of Sn Alloying On Morphology And Bandgap Transitions Via High–Resolution Transmission Electron Microscopy |
Authors: | Andelic, Milenka |
Advisor: | Botton, Gianluigi |
Department: | Materials Science and Engineering |
Keywords: | group IV semiconductors;core-shell nanowires;STEM and EDS characterization;bandgap measurement;alloys;EELS |
Publication Date: | 2024 |
Abstract: | This study investigates the impact of Sn alloying on the structural, electronic, and optical properties of core-shell Ge-GeSn nanowires, with Ge as the core and GeSn as the shell. Using advanced transmission electron microscopy (TEM) techniques, including High-Resolution Scanning TEM (STEM) with High-Angle Annular Dark Field (HAADF) imaging, Energy-Dispersive X-Ray Spectroscopy (EDS), and Electron Energy-Loss Spectroscopy (EELS), we achieve high spatial, energy, and momentum resolution. These methods reveal complex morphological changes and bandgap transitions within the Ge_(1-x)Sn_x nanowires. The study demonstrates that defect-free Ge-Ge_(1-x)Sn_(x) core-shell nanowires can be successfully synthesized by overcoming challenging growth conditions, achieving stable structures even with varying Sn content. Detailed sub-angstrom investigations reveal that these nanowires maintain stability and defect-free characteristics despite the presence of strain, which is alleviated by their core-shell morphology. Our findings show that increasing Sn content from 8 to 18 at.\% leads to a notable transition from an indirect to a direct bandgap, with the bandgap energy decreasing to approximately 0.2 eV at high Sn concentrations. This research highlights the significant role of Sn alloying in altering the characteristics of Ge-Ge_(1-x)Sn_(x) core-shell nanowires and confirms the transition to a direct bandgap with increased Sn content. |
URI: | http://hdl.handle.net/11375/30878 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Andelic_Milenka_finalsubmission2024November_PhD.pdf | 66.14 MB | Adobe PDF | View/Open |
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