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A bifractal nature of reticular patterns induced by oxygen plasma on polymer films.

Bae J, Lee IJ - Sci Rep (2015)

Bottom Line: The concept of a bifractal interface is successfully applied to reticular patterns induced by oxygen plasma on the surface of polymer films.Remarkably, it is uncovered that the dynamic roughening of the underlying structure is governed by a relaxation mechanism described by the Edwards-Wilkinson universality class with a conservative noise.The evidence for the basic phase, characterized by the negative roughness and growth exponents, has been elusive since its first theoretical consideration more than two decades ago.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Research Institute of Physics and Chemistry, Chonbuk National University, Jeonju, 561-756, Korea.

ABSTRACT
Plasma etching was demonstrated to be a promising tool for generating self-organized nano-patterns on various commercial films. Unfortunately, dynamic scaling approach toward fundamental understanding of the formation and growth of the plasma-induced nano-structure has not always been straightforward. The temporal evolution of self-aligned nano-patterns may often evolve with an additional scale-invariance, which leads to breakdown of the well-established dynamic scaling law. The concept of a bifractal interface is successfully applied to reticular patterns induced by oxygen plasma on the surface of polymer films. The reticular pattern, composed of nano-size self-aligned protuberances and underlying structure, develops two types of anomalous dynamic scaling characterized by super-roughening and intrinsic anomalous scaling, respectively. The diffusion and aggregation of short-cleaved chains under the plasma environment are responsible for the regular distribution of the nano-size protuberances. Remarkably, it is uncovered that the dynamic roughening of the underlying structure is governed by a relaxation mechanism described by the Edwards-Wilkinson universality class with a conservative noise. The evidence for the basic phase, characterized by the negative roughness and growth exponents, has been elusive since its first theoretical consideration more than two decades ago.

No MeSH data available.


Related in: MedlinePlus

The temporal dependence of the correlation length, , is shown in panel (a) and (b). The evolution of the interface width, , is displayed in panel (c) and (d). The subscripts n and u stand for the nano-size protuberances and underlying structure, respectively. The error bar on each data point indicates the standard deviation from the mean value determined from at least four different locations on the surface of each film. The measured slope and standard fitting error are written in each panel.
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f4: The temporal dependence of the correlation length, , is shown in panel (a) and (b). The evolution of the interface width, , is displayed in panel (c) and (d). The subscripts n and u stand for the nano-size protuberances and underlying structure, respectively. The error bar on each data point indicates the standard deviation from the mean value determined from at least four different locations on the surface of each film. The measured slope and standard fitting error are written in each panel.

Mentions: The results of bifractal analysis on the plasma-induced surface patterns are summarized in Fig. 4. The lines through the data points in each panel show a linear best fit of the scaling parameters in log-log scale. The crossover commonly occurring near t = 300 s is associated with the development of the low-lying bridges between the protuberant spots leading to the formation of the reticular pattern with closely packed pits. We notice that by the time at t = 330 s, the temperature of the polymer film under the oxygen plasma reaches the glass temperature known to take place at 21. By applying the dynamic scaling law, , we obtain the global roughness exponent of for the nano-size protuberances throughout the etching process, independent of the crossover. Interestingly, the height fluctuation of the underlying structure decreases over time with , while the lateral size increases with , resulting in a negative roughness exponent of above t = 300 s. The transition from the layer-by-layer etching to deroughening process displayed in Fig. 4(d) is closely associated with the glass temperature of the polymer film. Nevertheless, the rms roughness given by would actually increase with a positive slope of as shown in the inset of Fig. 2. In comparison with the data, we see that which was dominated by underlying structure in the early exposure times becomes controlled by the nano-size protuberances in the later times. Although the positive growth exponent () may agree with most of the kinetic roughening induced by either growth or etching process22, the dynamic scaling law based on a self-affine fractal would not work for the plasma-etched polymer surface.


A bifractal nature of reticular patterns induced by oxygen plasma on polymer films.

Bae J, Lee IJ - Sci Rep (2015)

The temporal dependence of the correlation length, , is shown in panel (a) and (b). The evolution of the interface width, , is displayed in panel (c) and (d). The subscripts n and u stand for the nano-size protuberances and underlying structure, respectively. The error bar on each data point indicates the standard deviation from the mean value determined from at least four different locations on the surface of each film. The measured slope and standard fitting error are written in each panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440523&req=5

f4: The temporal dependence of the correlation length, , is shown in panel (a) and (b). The evolution of the interface width, , is displayed in panel (c) and (d). The subscripts n and u stand for the nano-size protuberances and underlying structure, respectively. The error bar on each data point indicates the standard deviation from the mean value determined from at least four different locations on the surface of each film. The measured slope and standard fitting error are written in each panel.
Mentions: The results of bifractal analysis on the plasma-induced surface patterns are summarized in Fig. 4. The lines through the data points in each panel show a linear best fit of the scaling parameters in log-log scale. The crossover commonly occurring near t = 300 s is associated with the development of the low-lying bridges between the protuberant spots leading to the formation of the reticular pattern with closely packed pits. We notice that by the time at t = 330 s, the temperature of the polymer film under the oxygen plasma reaches the glass temperature known to take place at 21. By applying the dynamic scaling law, , we obtain the global roughness exponent of for the nano-size protuberances throughout the etching process, independent of the crossover. Interestingly, the height fluctuation of the underlying structure decreases over time with , while the lateral size increases with , resulting in a negative roughness exponent of above t = 300 s. The transition from the layer-by-layer etching to deroughening process displayed in Fig. 4(d) is closely associated with the glass temperature of the polymer film. Nevertheless, the rms roughness given by would actually increase with a positive slope of as shown in the inset of Fig. 2. In comparison with the data, we see that which was dominated by underlying structure in the early exposure times becomes controlled by the nano-size protuberances in the later times. Although the positive growth exponent () may agree with most of the kinetic roughening induced by either growth or etching process22, the dynamic scaling law based on a self-affine fractal would not work for the plasma-etched polymer surface.

Bottom Line: The concept of a bifractal interface is successfully applied to reticular patterns induced by oxygen plasma on the surface of polymer films.Remarkably, it is uncovered that the dynamic roughening of the underlying structure is governed by a relaxation mechanism described by the Edwards-Wilkinson universality class with a conservative noise.The evidence for the basic phase, characterized by the negative roughness and growth exponents, has been elusive since its first theoretical consideration more than two decades ago.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Research Institute of Physics and Chemistry, Chonbuk National University, Jeonju, 561-756, Korea.

ABSTRACT
Plasma etching was demonstrated to be a promising tool for generating self-organized nano-patterns on various commercial films. Unfortunately, dynamic scaling approach toward fundamental understanding of the formation and growth of the plasma-induced nano-structure has not always been straightforward. The temporal evolution of self-aligned nano-patterns may often evolve with an additional scale-invariance, which leads to breakdown of the well-established dynamic scaling law. The concept of a bifractal interface is successfully applied to reticular patterns induced by oxygen plasma on the surface of polymer films. The reticular pattern, composed of nano-size self-aligned protuberances and underlying structure, develops two types of anomalous dynamic scaling characterized by super-roughening and intrinsic anomalous scaling, respectively. The diffusion and aggregation of short-cleaved chains under the plasma environment are responsible for the regular distribution of the nano-size protuberances. Remarkably, it is uncovered that the dynamic roughening of the underlying structure is governed by a relaxation mechanism described by the Edwards-Wilkinson universality class with a conservative noise. The evidence for the basic phase, characterized by the negative roughness and growth exponents, has been elusive since its first theoretical consideration more than two decades ago.

No MeSH data available.


Related in: MedlinePlus