Oxidation Mechanism of Si1-xGex Nanowires with Au Catalyst Tip as a Function of Ge Content

Jung Min Bae, Kwang Sik Jeong, Woo Jung Lee, Min Baik, Jaehun Park, Mann-Ho Cho

Research output: Contribution to journalArticle

Abstract

Si1-xGex nanowires (NWs) (0.22 ≤ x ≤ 0.78) were synthesized using a vapor-liquid-solid procedure with a Au catalyst. We measured the intrinsic physical, chemical, and electrical properties of the oxidized Si1-xGex NWs using several techniques, including transmission electron microscopy, X-ray photoemission spectroscopy, and optical pump-THz probe spectroscopy. We suggest two distinct oxidation mechanisms depending on the Ge content in the Si1-xGex NWs: (i) when the Ge content is around 0.22, a Au catalytic effect brings about oxidation in both the axial and lateral directions; and (ii) when the Ge content is greater than 0.22, the Au tip is detached from the NW body and does not act as a catalyst, which is a result of the high degree of Ge-atom participation in the oxidation process. Additionally, we measured the photoconductivity decay time distribution for the Si1-xGex NWs before and after oxidation process; the decay time is significantly shortened in oxidized Si1-xGex NWs (0.22 < x), whereas it is maintained for Si-rich Si1-xGex NWs (x ≈ 0.22) as compared to the as-grown Si1-xGex NWs. It indicates that the number of defect states is generated with the formation of defective Ge oxide at the oxide-shell-layer/Si1-xGex-core-NW interface.

Original languageEnglish
Pages (from-to)37411-37418
Number of pages8
JournalACS Applied Materials and Interfaces
Volume9
Issue number42
DOIs
Publication statusPublished - 2017 Oct 25

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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