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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.

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.


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Model of group IV semiconductor NW growth by MBE. The NW has a length L and a diameter D. Elemental compounds are evaporated with a rate J and impinge on the surface as well as on the Au seed particle, positioned at the top of the NW. Once adsorbed, the adatoms diffuse on the substrate and on the NW sidewalls with diffusion lengths λs and λf, respectively. Au adatoms can also diffuse away from the seed particle.
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Figure 1: Model of group IV semiconductor NW growth by MBE. The NW has a length L and a diameter D. Elemental compounds are evaporated with a rate J and impinge on the surface as well as on the Au seed particle, positioned at the top of the NW. Once adsorbed, the adatoms diffuse on the substrate and on the NW sidewalls with diffusion lengths λs and λf, respectively. Au adatoms can also diffuse away from the seed particle.

Mentions: As illustrated in Figure 1 for the MBE growth, the ratio between the exposed surface of a seed particle and the collection area between the seed particles is usually small. Due to the low pressure in the growth chamber, the direct impingement of elemental compounds onto the seed particle has a small probability to occur. Therefore, growth predominantly proceeds from the diffusion of elemental compounds that adsorb on the substrate between the seed particles. The adatoms reach the seed particles after diffusing on the substrate and the sidewalls with different diffusion length coefficients, λS and λf, respectively. As surface diffusion is a rather slow process, it is only because the crystallization at the interface between the seed particles and the NW is high enough that NWs emerge from the film growth. Such mass transport mechanism yields a NW length that is inversely proportional to the NW diameter [3,4].


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)

Model of group IV semiconductor NW growth by MBE. The NW has a length L and a diameter D. Elemental compounds are evaporated with a rate J and impinge on the surface as well as on the Au seed particle, positioned at the top of the NW. Once adsorbed, the adatoms diffuse on the substrate and on the NW sidewalls with diffusion lengths λs and λf, respectively. Au adatoms can also diffuse away from the seed particle.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Model of group IV semiconductor NW growth by MBE. The NW has a length L and a diameter D. Elemental compounds are evaporated with a rate J and impinge on the surface as well as on the Au seed particle, positioned at the top of the NW. Once adsorbed, the adatoms diffuse on the substrate and on the NW sidewalls with diffusion lengths λs and λf, respectively. Au adatoms can also diffuse away from the seed particle.
Mentions: As illustrated in Figure 1 for the MBE growth, the ratio between the exposed surface of a seed particle and the collection area between the seed particles is usually small. Due to the low pressure in the growth chamber, the direct impingement of elemental compounds onto the seed particle has a small probability to occur. Therefore, growth predominantly proceeds from the diffusion of elemental compounds that adsorb on the substrate between the seed particles. The adatoms reach the seed particles after diffusing on the substrate and the sidewalls with different diffusion length coefficients, λS and λf, respectively. As surface diffusion is a rather slow process, it is only because the crystallization at the interface between the seed particles and the NW is high enough that NWs emerge from the film growth. Such mass transport mechanism yields a NW length that is inversely proportional to the NW diameter [3,4].

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