Tapering-free monocrystalline Ge nanowires synthesized via plasma-assisted VLS using in and Sn catalysts
(2022) In Nanotechnology 33(40).- Abstract
In and Sn are the type of catalysts which do not introduce deep level electrical defects within the bandgap of germanium (Ge). However, Ge nanowires produced using these catalysts usually have a large diameter, a tapered morphology, and mixed crystalline and amorphous phases. In this study, we show that plasma-assisted vapor-liquid-solid (PA-VLS) method can be used to synthesize Ge nanowires. Moreover, at certain parameter domains, the sidewall deposition issues of this synthesis method can be avoided and long, thin tapering-free monocrystalline Ge nanowires can be obtained with In and Sn catalysts. We find two quite different parameter domains where Ge nanowire growth can occur via PA-VLS using In and Sn catalysts: (i) a low... (More)
In and Sn are the type of catalysts which do not introduce deep level electrical defects within the bandgap of germanium (Ge). However, Ge nanowires produced using these catalysts usually have a large diameter, a tapered morphology, and mixed crystalline and amorphous phases. In this study, we show that plasma-assisted vapor-liquid-solid (PA-VLS) method can be used to synthesize Ge nanowires. Moreover, at certain parameter domains, the sidewall deposition issues of this synthesis method can be avoided and long, thin tapering-free monocrystalline Ge nanowires can be obtained with In and Sn catalysts. We find two quite different parameter domains where Ge nanowire growth can occur via PA-VLS using In and Sn catalysts: (i) a low temperature-low pressure domain, below ∼235 °C at a GeH4 partial pressure of ∼6 mTorr, where supersaturation in the catalyst occurs thanks to the low solubility of Ge in the catalysts, and (ii) a high temperature-high pressure domain, at ∼400 °C and a GeH4 partial pressure above ∼20 mTorr, where supersaturation occurs thanks to the high GeH4 concentration. While growth at 235 °C results in tapered short wires, operating at 400 °C enables cylindrical nanowire growth. With the increase of growth temperature, the crystalline structure of the nanowires changes from multi-crystalline to mono-crystalline and their growth rate increases from ∼0.3 nm s-1 to 5 nm s-1. The cylindrical Ge nanowires grown at 400°C usually have a length of few microns and a radius of around 10 nm, which is well below the Bohr exciton radius in bulk Ge (24.3 nm). To explain the growth mechanism, a detailed growth model based on the key chemical reactions is provided.
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- author
- Tang, Jian ; Wang, Jun ; Maurice, Jean Luc ; Chen, Wanghua ; Foldyna, Martin ; Yu, Linwei ; Leshchenko, Egor D. LU ; Dubrovskii, Vladimir G. and Cabarrocas, Pere Roca I.
- organization
- publishing date
- 2022-10-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- germanium nanowires, In, plasma-assisted VLS, Sn, tapering-free, ultra-thin
- in
- Nanotechnology
- volume
- 33
- issue
- 40
- article number
- 405602
- publisher
- IOP Publishing
- external identifiers
-
- pmid:35196259
- scopus:85134632273
- ISSN
- 0957-4484
- DOI
- 10.1088/1361-6528/ac57d4
- language
- English
- LU publication?
- yes
- id
- 55bd8f16-b65f-4965-bf78-ad8352eb38ec
- date added to LUP
- 2022-09-23 14:51:52
- date last changed
- 2024-04-15 19:34:14
@article{55bd8f16-b65f-4965-bf78-ad8352eb38ec,
abstract = {{<p>In and Sn are the type of catalysts which do not introduce deep level electrical defects within the bandgap of germanium (Ge). However, Ge nanowires produced using these catalysts usually have a large diameter, a tapered morphology, and mixed crystalline and amorphous phases. In this study, we show that plasma-assisted vapor-liquid-solid (PA-VLS) method can be used to synthesize Ge nanowires. Moreover, at certain parameter domains, the sidewall deposition issues of this synthesis method can be avoided and long, thin tapering-free monocrystalline Ge nanowires can be obtained with In and Sn catalysts. We find two quite different parameter domains where Ge nanowire growth can occur via PA-VLS using In and Sn catalysts: (i) a low temperature-low pressure domain, below ∼235 °C at a GeH4 partial pressure of ∼6 mTorr, where supersaturation in the catalyst occurs thanks to the low solubility of Ge in the catalysts, and (ii) a high temperature-high pressure domain, at ∼400 °C and a GeH4 partial pressure above ∼20 mTorr, where supersaturation occurs thanks to the high GeH4 concentration. While growth at 235 °C results in tapered short wires, operating at 400 °C enables cylindrical nanowire growth. With the increase of growth temperature, the crystalline structure of the nanowires changes from multi-crystalline to mono-crystalline and their growth rate increases from ∼0.3 nm s-1 to 5 nm s-1. The cylindrical Ge nanowires grown at 400°C usually have a length of few microns and a radius of around 10 nm, which is well below the Bohr exciton radius in bulk Ge (24.3 nm). To explain the growth mechanism, a detailed growth model based on the key chemical reactions is provided. </p>}},
author = {{Tang, Jian and Wang, Jun and Maurice, Jean Luc and Chen, Wanghua and Foldyna, Martin and Yu, Linwei and Leshchenko, Egor D. and Dubrovskii, Vladimir G. and Cabarrocas, Pere Roca I.}},
issn = {{0957-4484}},
keywords = {{germanium nanowires; In; plasma-assisted VLS; Sn; tapering-free; ultra-thin}},
language = {{eng}},
month = {{10}},
number = {{40}},
publisher = {{IOP Publishing}},
series = {{Nanotechnology}},
title = {{Tapering-free monocrystalline Ge nanowires synthesized via plasma-assisted VLS using in and Sn catalysts}},
url = {{http://dx.doi.org/10.1088/1361-6528/ac57d4}},
doi = {{10.1088/1361-6528/ac57d4}},
volume = {{33}},
year = {{2022}},
}