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Synthesis of long group IV semiconductor nanowires by molecular beam epitaxy.

Xu T, Sulerzycki J, Nys JP, Patriarche G, Grandidier B, Stiévenard D - Nanoscale Res Lett (2011)

Bottom Line: Structural studies of both types of NWs performed with electron microscopies reveal a marked difference between the roughnesses of their respective sidewalls.As the investigation of their length dependence on their diameter indicates that the growth of the NWs predominantly proceeds through the diffusion of adatoms from the substrate up along the sidewalls, difference in the sidewall roughness qualitatively explains the length variation measured between both types of NWs.The formation of atomically flat {111} sidewalls on the <110>-oriented Ge NWs accounts for a larger diffusion length.

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Affiliation: Département ISEN, Institut d'Electronique, de Microélectronique et de Nanotechnologie, IEMN (CNRS, UMR 8520), 41 bd Vauban, 59046 Lille Cedex, France. bruno.grandidier@isen.fr.

ABSTRACT
We report the growth of Si and Ge nanowires (NWs) on a Si(111) surface by molecular beam epitaxy. While Si NWs grow perpendicular to the surface, two types of growth axes are found for the Ge NWs. Structural studies of both types of NWs performed with electron microscopies reveal a marked difference between the roughnesses of their respective sidewalls. As the investigation of their length dependence on their diameter indicates that the growth of the NWs predominantly proceeds through the diffusion of adatoms from the substrate up along the sidewalls, difference in the sidewall roughness qualitatively explains the length variation measured between both types of NWs. The formation of atomically flat {111} sidewalls on the <110>-oriented Ge NWs accounts for a larger diffusion length.

No MeSH data available.


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Correlation between the length and the diameter of <111>-oriented Si NWs and <110>-oriented Ge NWs. For Ge NWs, the data are measured for two different growth times. The evaporation rate for both experiments was 1.5 ± 0.2 Å/s.
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Figure 5: Correlation between the length and the diameter of <111>-oriented Si NWs and <110>-oriented Ge NWs. For Ge NWs, the data are measured for two different growth times. The evaporation rate for both experiments was 1.5 ± 0.2 Å/s.

Mentions: As already described in the introduction, the growth of NWs by MBE predominantly proceeds through the diffusion of adatoms that adsorb on the substrate in between the NWs. Indeed, if we consider the surface of the seed particle exposed to the flux of elemental compounds and the area surrounding the NWs that serves as a reservoir to collect adatoms for the NW growth, their ratio is usually quite small. When the NW is still short, typically at the beginning of the growth, the contribution of the adatoms diffusing from the substrate up along the NW is thus the strongest to the growth rate. This mechanism implies that the crystallization rate at the interface between the seed particle and the NW is related to the flow of diffusing adatoms that become incorporated when they reach the circumference of the interface [4]. It yields a characteristic signature: the NW length varies like the inverse of the diameter. Such a behavior appears in Figure 5a for the case of the <111>-oriented Si NWs grown by MBE.


Synthesis of long group IV semiconductor nanowires by molecular beam epitaxy.

Xu T, Sulerzycki J, Nys JP, Patriarche G, Grandidier B, Stiévenard D - Nanoscale Res Lett (2011)

Correlation between the length and the diameter of <111>-oriented Si NWs and <110>-oriented Ge NWs. For Ge NWs, the data are measured for two different growth times. The evaporation rate for both experiments was 1.5 ± 0.2 Å/s.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211158&req=5

Figure 5: Correlation between the length and the diameter of <111>-oriented Si NWs and <110>-oriented Ge NWs. For Ge NWs, the data are measured for two different growth times. The evaporation rate for both experiments was 1.5 ± 0.2 Å/s.
Mentions: As already described in the introduction, the growth of NWs by MBE predominantly proceeds through the diffusion of adatoms that adsorb on the substrate in between the NWs. Indeed, if we consider the surface of the seed particle exposed to the flux of elemental compounds and the area surrounding the NWs that serves as a reservoir to collect adatoms for the NW growth, their ratio is usually quite small. When the NW is still short, typically at the beginning of the growth, the contribution of the adatoms diffusing from the substrate up along the NW is thus the strongest to the growth rate. This mechanism implies that the crystallization rate at the interface between the seed particle and the NW is related to the flow of diffusing adatoms that become incorporated when they reach the circumference of the interface [4]. It yields a characteristic signature: the NW length varies like the inverse of the diameter. Such a behavior appears in Figure 5a for the case of the <111>-oriented Si NWs grown by MBE.

Bottom Line: Structural studies of both types of NWs performed with electron microscopies reveal a marked difference between the roughnesses of their respective sidewalls.As the investigation of their length dependence on their diameter indicates that the growth of the NWs predominantly proceeds through the diffusion of adatoms from the substrate up along the sidewalls, difference in the sidewall roughness qualitatively explains the length variation measured between both types of NWs.The formation of atomically flat {111} sidewalls on the <110>-oriented Ge NWs accounts for a larger diffusion length.

View Article: PubMed Central - HTML - PubMed

Affiliation: Département ISEN, Institut d'Electronique, de Microélectronique et de Nanotechnologie, IEMN (CNRS, UMR 8520), 41 bd Vauban, 59046 Lille Cedex, France. bruno.grandidier@isen.fr.

ABSTRACT
We report the growth of Si and Ge nanowires (NWs) on a Si(111) surface by molecular beam epitaxy. While Si NWs grow perpendicular to the surface, two types of growth axes are found for the Ge NWs. Structural studies of both types of NWs performed with electron microscopies reveal a marked difference between the roughnesses of their respective sidewalls. As the investigation of their length dependence on their diameter indicates that the growth of the NWs predominantly proceeds through the diffusion of adatoms from the substrate up along the sidewalls, difference in the sidewall roughness qualitatively explains the length variation measured between both types of NWs. The formation of atomically flat {111} sidewalls on the <110>-oriented Ge NWs accounts for a larger diffusion length.

No MeSH data available.


Related in: MedlinePlus