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Self-organized chains of nanodots induced by an off-normal incident beam.

Lee S, Wang L, Lu W - Nanoscale Res Lett (2011)

Bottom Line: We propose a model to show that under off-normal bombardment of an incident ion beam, a solid surface may spontaneously form nanoscale dots lining up into chains perpendicular to the incident beam direction.We attribute the self-organization behavior to surface instability under concurrent surface kinetics and to a shadow effect that causes the self-alignment of dots.The fundamental mechanism may be applicable to diverse systems, suggesting an effective approach for nanofabrication.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA. weilu@umich.edu.

ABSTRACT
We propose a model to show that under off-normal bombardment of an incident ion beam, a solid surface may spontaneously form nanoscale dots lining up into chains perpendicular to the incident beam direction. These dots demonstrate a highly ordered hexagonal pattern. We attribute the self-organization behavior to surface instability under concurrent surface kinetics and to a shadow effect that causes the self-alignment of dots. The fundamental mechanism may be applicable to diverse systems, suggesting an effective approach for nanofabrication.

No MeSH data available.


Related in: MedlinePlus

Schematic of a hexagonal pattern of dots lined up along the y axis. The formed line is perpendicular to the direction of the incident beam. Dot A would be partially shadowed by B and C if it shifts to the left, when mass accumulation at its front would bring it back to line up with B and C. Anisotropic smoothing causes the distance between dots anisotropic, i.e., a > b.
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Figure 1: Schematic of a hexagonal pattern of dots lined up along the y axis. The formed line is perpendicular to the direction of the incident beam. Dot A would be partially shadowed by B and C if it shifts to the left, when mass accumulation at its front would bring it back to line up with B and C. Anisotropic smoothing causes the distance between dots anisotropic, i.e., a > b.

Mentions: Now, we discuss how the shadow effect causes the dots to line up into chains. Consider a hexagonal pattern of dots as shown in Figure 1. These dots line up into chains along the y axis. Dot A would be partially shadowed by B and C if it shifts to the left, when mass accumulation at its front would bring it back to line up with B and C. Similarly, dot A would be exposed to more sputtering if it shifts to the right and would gradually move back to be in-line with B and C. The anisotropic smoothing given by the third term in Equation 2 causes the wavelength in the x direction to be larger than that in the y direction. As a result, the distance between dots is not isotropic, i.e., a > b in Figure 1. This behavior is consistent with experimental observations.


Self-organized chains of nanodots induced by an off-normal incident beam.

Lee S, Wang L, Lu W - Nanoscale Res Lett (2011)

Schematic of a hexagonal pattern of dots lined up along the y axis. The formed line is perpendicular to the direction of the incident beam. Dot A would be partially shadowed by B and C if it shifts to the left, when mass accumulation at its front would bring it back to line up with B and C. Anisotropic smoothing causes the distance between dots anisotropic, i.e., a > b.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211850&req=5

Figure 1: Schematic of a hexagonal pattern of dots lined up along the y axis. The formed line is perpendicular to the direction of the incident beam. Dot A would be partially shadowed by B and C if it shifts to the left, when mass accumulation at its front would bring it back to line up with B and C. Anisotropic smoothing causes the distance between dots anisotropic, i.e., a > b.
Mentions: Now, we discuss how the shadow effect causes the dots to line up into chains. Consider a hexagonal pattern of dots as shown in Figure 1. These dots line up into chains along the y axis. Dot A would be partially shadowed by B and C if it shifts to the left, when mass accumulation at its front would bring it back to line up with B and C. Similarly, dot A would be exposed to more sputtering if it shifts to the right and would gradually move back to be in-line with B and C. The anisotropic smoothing given by the third term in Equation 2 causes the wavelength in the x direction to be larger than that in the y direction. As a result, the distance between dots is not isotropic, i.e., a > b in Figure 1. This behavior is consistent with experimental observations.

Bottom Line: We propose a model to show that under off-normal bombardment of an incident ion beam, a solid surface may spontaneously form nanoscale dots lining up into chains perpendicular to the incident beam direction.We attribute the self-organization behavior to surface instability under concurrent surface kinetics and to a shadow effect that causes the self-alignment of dots.The fundamental mechanism may be applicable to diverse systems, suggesting an effective approach for nanofabrication.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA. weilu@umich.edu.

ABSTRACT
We propose a model to show that under off-normal bombardment of an incident ion beam, a solid surface may spontaneously form nanoscale dots lining up into chains perpendicular to the incident beam direction. These dots demonstrate a highly ordered hexagonal pattern. We attribute the self-organization behavior to surface instability under concurrent surface kinetics and to a shadow effect that causes the self-alignment of dots. The fundamental mechanism may be applicable to diverse systems, suggesting an effective approach for nanofabrication.

No MeSH data available.


Related in: MedlinePlus