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Shrinking of Solid-state Nanopores by Direct Thermal Heating.

Asghar W, Ilyas A, Billo JA, Iqbal SM - Nanoscale Res Lett (2011)

Bottom Line: Direct heating results in shrinking of the silicon dioxide nanopores.The inbuilt stress in the oxide film is also reduced due to annealing.The surface composition of the pore walls remains the same during the shrinking process.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical Engineering, University of Texas at Arlington, Arlington, TX 76019, USA. smiqbal@uta.edu.

ABSTRACT
Solid-state nanopores have emerged as useful single-molecule sensors for DNA and proteins. A novel and simple technique for solid-state nanopore fabrication is reported here. The process involves direct thermal heating of 100 to 300 nm nanopores, made by focused ion beam (FIB) milling in free-standing membranes. Direct heating results in shrinking of the silicon dioxide nanopores. The free-standing silicon dioxide membrane is softened and adatoms diffuse to a lower surface free energy. The model predicts the dynamics of the shrinking process as validated by experiments. The method described herein, can process many samples at one time. The inbuilt stress in the oxide film is also reduced due to annealing. The surface composition of the pore walls remains the same during the shrinking process. The linear shrinkage rate gives a reproducible way to control the diameter of a pore with nanometer precision.

No MeSH data available.


Related in: MedlinePlus

Plot of pore diameter vs time at different temperatures. This plot is based on TEM micrographs of different nanopores processed at different temperatures. No change in pore size is seen after 20 min at 900°C. The pore shrinkage rate increased with increasing temperature. Note: average diameter of the nanopore = sqrt (long axis × short axis). All the shrinking processes show almost linear shrinking behavior.
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Figure 5: Plot of pore diameter vs time at different temperatures. This plot is based on TEM micrographs of different nanopores processed at different temperatures. No change in pore size is seen after 20 min at 900°C. The pore shrinkage rate increased with increasing temperature. Note: average diameter of the nanopore = sqrt (long axis × short axis). All the shrinking processes show almost linear shrinking behavior.

Mentions: The nanopore shrinking process was characterized at different temperatures as shown in Figure 5. The nanopore had no shrinking or expansion at 900°C. When the temperature was increased above 1000°C, the pore morphology started changing due to the diffusion and the viscous flow of oxide. The average nanopore shrinking rate was ~22 nm/min at 1150°C, which increased to 80 nm/min when the temperature was raised to 1250°C. At higher temperatures, the shrinking process was difficult to control precisely at the nano scale. When the nanopore diameter was reduced to tens of nanometers, low processing temperature (<1150°C) was used to accurately control the shrinking.


Shrinking of Solid-state Nanopores by Direct Thermal Heating.

Asghar W, Ilyas A, Billo JA, Iqbal SM - Nanoscale Res Lett (2011)

Plot of pore diameter vs time at different temperatures. This plot is based on TEM micrographs of different nanopores processed at different temperatures. No change in pore size is seen after 20 min at 900°C. The pore shrinkage rate increased with increasing temperature. Note: average diameter of the nanopore = sqrt (long axis × short axis). All the shrinking processes show almost linear shrinking behavior.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211463&req=5

Figure 5: Plot of pore diameter vs time at different temperatures. This plot is based on TEM micrographs of different nanopores processed at different temperatures. No change in pore size is seen after 20 min at 900°C. The pore shrinkage rate increased with increasing temperature. Note: average diameter of the nanopore = sqrt (long axis × short axis). All the shrinking processes show almost linear shrinking behavior.
Mentions: The nanopore shrinking process was characterized at different temperatures as shown in Figure 5. The nanopore had no shrinking or expansion at 900°C. When the temperature was increased above 1000°C, the pore morphology started changing due to the diffusion and the viscous flow of oxide. The average nanopore shrinking rate was ~22 nm/min at 1150°C, which increased to 80 nm/min when the temperature was raised to 1250°C. At higher temperatures, the shrinking process was difficult to control precisely at the nano scale. When the nanopore diameter was reduced to tens of nanometers, low processing temperature (<1150°C) was used to accurately control the shrinking.

Bottom Line: Direct heating results in shrinking of the silicon dioxide nanopores.The inbuilt stress in the oxide film is also reduced due to annealing.The surface composition of the pore walls remains the same during the shrinking process.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical Engineering, University of Texas at Arlington, Arlington, TX 76019, USA. smiqbal@uta.edu.

ABSTRACT
Solid-state nanopores have emerged as useful single-molecule sensors for DNA and proteins. A novel and simple technique for solid-state nanopore fabrication is reported here. The process involves direct thermal heating of 100 to 300 nm nanopores, made by focused ion beam (FIB) milling in free-standing membranes. Direct heating results in shrinking of the silicon dioxide nanopores. The free-standing silicon dioxide membrane is softened and adatoms diffuse to a lower surface free energy. The model predicts the dynamics of the shrinking process as validated by experiments. The method described herein, can process many samples at one time. The inbuilt stress in the oxide film is also reduced due to annealing. The surface composition of the pore walls remains the same during the shrinking process. The linear shrinkage rate gives a reproducible way to control the diameter of a pore with nanometer precision.

No MeSH data available.


Related in: MedlinePlus