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 journalArticlepeer-review

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

Bibliographical note

Funding Information:
This work was partially supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (Grant 2015R1A2A1A01007560) and partially supported by the Korea Research Institute of Standards and Science under the Metrology Research Center project. The authors are grateful for the valuable help in the experiments performed using the fs-THz spectroscopy beam-lines at the Pohang Light Source (PLS).

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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