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Combinatorial growth of Si nanoribbons.

Park TE, Lee KY, Kim I, Chang J, Voorhees P, Choi HJ - Nanoscale Res Lett (2011)

Bottom Line: These twins appear to drive the lateral growth by a reentrant twin mechanism.These twins also create a mirror-like crystallographic configuration in the anisotropic surface energy state and appear to further drive lateral saw-like edge growth in the < 112 > direction.These outcomes indicate that the Si NRs are grown by a combination of the two mechanisms of a Pt-catalyst-assisted VLS mechanism for longitudinal growth and a twin-assisted VS mechanism for lateral growth.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, South Korea. hjc@yonsei.ac.kr.

ABSTRACT
Silicon nanoribbons (Si NRs) with a thickness of about 30 nm and a width up to a few micrometers were synthesized. Systematic observations indicate that Si NRs evolve via the following sequences: the growth of basal nanowires assisted with a Pt catalyst by a vapor-liquid-solid (VLS) mechanism, followed by the formation of saw-like edges on the basal nanowires and the planar filling of those edges by a vapor-solid (VS) mechanism. Si NRs have twins along the longitudinal < 110 > growth of the basal nanowires that also extend in < 112 > direction to edge of NRs. These twins appear to drive the lateral growth by a reentrant twin mechanism. These twins also create a mirror-like crystallographic configuration in the anisotropic surface energy state and appear to further drive lateral saw-like edge growth in the < 112 > direction. These outcomes indicate that the Si NRs are grown by a combination of the two mechanisms of a Pt-catalyst-assisted VLS mechanism for longitudinal growth and a twin-assisted VS mechanism for lateral growth.

No MeSH data available.


TEM images of NR. (a-e) TEM images showing the evolutionary stages of the NR; basal nanowire, saw-like edges on the basal nanowire, and the NR.
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Figure 2: TEM images of NR. (a-e) TEM images showing the evolutionary stages of the NR; basal nanowire, saw-like edges on the basal nanowire, and the NR.

Mentions: To address the growth mechanism, the evolution of Si NRs over time was examined by TEM. While the degree of evolution differed from ribbon to ribbon, a general trend could be acknowledged. Figure 2a-e shows the typical sequential evolution of the NRs with a processing time interval of 2 min. Initially, Si basal nanowires grew, as shown in Figure 2a. Subsequently, the saw-like edges began to grow along the basal nanowires (Figure 2b-d), the interspaces between the saw-like edges filled, and eventually the NRs shown in Figure 2e resulted. Our observation indicated that the triangular islands are distributed along a ribbon uniformly, as shown in Figure 2b, c. Meanwhile, the average number of islands that is estimated from 15 ribbons is 9 ± 3/μm. These indicate that the distribution of islands in a single ribbon is rather uniform; however, is not quite uniform among different ribbons under same synthesis conditions.


Combinatorial growth of Si nanoribbons.

Park TE, Lee KY, Kim I, Chang J, Voorhees P, Choi HJ - Nanoscale Res Lett (2011)

TEM images of NR. (a-e) TEM images showing the evolutionary stages of the NR; basal nanowire, saw-like edges on the basal nanowire, and the NR.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211989&req=5

Figure 2: TEM images of NR. (a-e) TEM images showing the evolutionary stages of the NR; basal nanowire, saw-like edges on the basal nanowire, and the NR.
Mentions: To address the growth mechanism, the evolution of Si NRs over time was examined by TEM. While the degree of evolution differed from ribbon to ribbon, a general trend could be acknowledged. Figure 2a-e shows the typical sequential evolution of the NRs with a processing time interval of 2 min. Initially, Si basal nanowires grew, as shown in Figure 2a. Subsequently, the saw-like edges began to grow along the basal nanowires (Figure 2b-d), the interspaces between the saw-like edges filled, and eventually the NRs shown in Figure 2e resulted. Our observation indicated that the triangular islands are distributed along a ribbon uniformly, as shown in Figure 2b, c. Meanwhile, the average number of islands that is estimated from 15 ribbons is 9 ± 3/μm. These indicate that the distribution of islands in a single ribbon is rather uniform; however, is not quite uniform among different ribbons under same synthesis conditions.

Bottom Line: These twins appear to drive the lateral growth by a reentrant twin mechanism.These twins also create a mirror-like crystallographic configuration in the anisotropic surface energy state and appear to further drive lateral saw-like edge growth in the < 112 > direction.These outcomes indicate that the Si NRs are grown by a combination of the two mechanisms of a Pt-catalyst-assisted VLS mechanism for longitudinal growth and a twin-assisted VS mechanism for lateral growth.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, South Korea. hjc@yonsei.ac.kr.

ABSTRACT
Silicon nanoribbons (Si NRs) with a thickness of about 30 nm and a width up to a few micrometers were synthesized. Systematic observations indicate that Si NRs evolve via the following sequences: the growth of basal nanowires assisted with a Pt catalyst by a vapor-liquid-solid (VLS) mechanism, followed by the formation of saw-like edges on the basal nanowires and the planar filling of those edges by a vapor-solid (VS) mechanism. Si NRs have twins along the longitudinal < 110 > growth of the basal nanowires that also extend in < 112 > direction to edge of NRs. These twins appear to drive the lateral growth by a reentrant twin mechanism. These twins also create a mirror-like crystallographic configuration in the anisotropic surface energy state and appear to further drive lateral saw-like edge growth in the < 112 > direction. These outcomes indicate that the Si NRs are grown by a combination of the two mechanisms of a Pt-catalyst-assisted VLS mechanism for longitudinal growth and a twin-assisted VS mechanism for lateral growth.

No MeSH data available.