Taper-free and vertically oriented Ge nanowires on Ge/Si substrates grown by a two-temperature process

Kim, Jung Hyuk and Moon, So Ra and Yoon, Hyun Sik and Jung, Jae Hun and Kim, Yong and Chen, Zhi Gang and Zou, Jin and Choi, Duk Yong and Joyce, Hannah J. and Gao, Qiang and Tan, H. Hoe and Jagadish, Chennupati (2012) Taper-free and vertically oriented Ge nanowires on Ge/Si substrates grown by a two-temperature process. Crystal Growth and Design, 12 (1). pp. 135-141. ISSN 1528-7483

Abstract

Taper-free and vertically oriented Ge nanowires were grown on Si (111) substrates by chemical vapor deposition with Au nanoparticle catalysts. To achieve vertical nanowire growth on the highly lattice mismatched Si substrate, a thin Ge buffer layer was first deposited, and to achieve taper-free nanowire growth, a two-temperature process was employed. The two-temperature process consisted of a brief initial base growth step at high temperature followed by prolonged growth at lower temperature. Taper-free and defect-free Ge nanowires grew successfully even at 270 °C, which is 90 °C lower than the bulk eutectic temperature. The yield of vertical and taper-free nanowires is over 90%, comparable to that of vertical but tapered nanowires grown by the conventional one-temperature process. This method is of practical importance and can be reliably used to develop novel nanowire-based devices on relatively cheap Si substrates. Additionally, we observed that the activation energy of Ge nanowire growth by the two-temperature process is dependent on Au nanoparticle size. The low activation energy (∼5 kcal/mol) for 30 and 50 nm diameter Au nanoparticles suggests that the decomposition of gaseous species on the catalytic Au surface is a rate-limiting step. A higher activation energy (∼14 kcal/mol) was determined for 100 nm diameter Au nanoparticles which suggests that larger Au nanoparticles are partially solidified and that growth kinetics become the rate-limiting step.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty / Department / School: No Faculty
Date Deposited: 21 Jun 2017 05:35
Last Modified: 21 Jun 2017 05:35
Uncontrolled Keywords: Au nanoparticle; Au surfaces; Defect-free; Eutectic temperature; Gaseous species; Growth steps; High temperature; Lattice-mismatched; Low-activation energy; Nanowire growth; Practical importance; Rate-limiting steps; Si substrates; Si(111) substrate; Two-temperature; Coating Materials; Coating Techniques; Chemical Products Generally; Chemistry; Solid State Physics; Nanotechnology; Electric and Magnetic Materials;
Fields of Research : 09 Engineering > 0912 Materials Engineering > 091299 Materials Engineering not elsewhere classified
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Identification Number or DOI: 10.1021/cg2008914
URI: http://eprints.usq.edu.au/id/eprint/31728

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